Pressure Sores

1. Pressure sores are a result of ischemic necrosis of varying depths up to bone which constitutes the internal pressure point. Any part of the bed or a chair usually constitutes such an external pressure point. The necrosis occurs between the two. In reality unless diagnosed very early, a pressure sore reaches the bone very quickly because fat is extremely sensitive to devascularisation.
2. Pressure sores might occur in a matter of hours and not infrequently are the source of toxicity or fever. In fact pressure sores might be missed completely unless nursing care is adequate and the patient is inspected carefully when he is cleaned or sponged. Fever of unknown origin in a bed ridden patient might in fact be the symptom of deep seated, hidden (missed) pressure sore and has all the features of a necrotic, foul smelling abscess when the site is located and drained. While debridement is essential over days, care must be taken not to be too aggressive lest you enter a normal area of hyperemia and cut a vessel. Torrential bleeding can then follow and such an event is difficult to manage in the ward. Also many apparently superficial pressure sores might in fact be deepithelialised areas covering a cone shaped necrosis and need to be examined properly.
3. There is little difference in the way pressure sores are covered with skin flaps as compared to ordinary wounds. However pressure sores in non-sensate skin and those occurring in areas of skin with normal sensation are two entirely different entities. The prognosis of the former is much worse in the long term. The treatment of pressure sores also depends on the kind of patient they have occurred in.
4. In view of the above, pressure sores may be roughly classified as follows so that treatment can be organized.
a. Pressure sores in sensate areas in individuals who become very ill or unconscious but are likely to recover from their illness and will be up and about in a reasonable period, almost always heal spontaneously, rarely requiring skin cover. Pressure sores on the scalp may be an exception because scalp is rigid and will not contract. Here local flaps will usually suffice though large defects have been covered with free flaps.
b. Pressure sores in otherwise sensate areas in individuals in a terminal illness (multi-organ failure, extreme old age) in whom a recovery is unlikely need to have a certain philosophical approach and treatment is decided in consultation with relatives.

c. A group of patients from the above category who will survive their grave illness but will go in to a vegetative state with pressure sores may be treated surgically if adequate nursing care either in the hospital or at home is assured. Deep pressure sores will need flap cover.

d. Pressure sores in non-sensate skin where paralysis of corresponding muscles is present but where protective movements are not completely abolished e.g. in leprosy are best treated with dressings and suitable footwear or protective clothing to the hand. In the foot local flaps are often employed after excision of internal bony pressure points followed by suitable footwear.
e. Pressure sores over non-sensate skin in patients who do not have corresponding muscular paralysis e.g. diabetes can have either occasional surgical treatment such as excision of an offending bony point, debridement or skin graft or conservative treatment with dressings etc. as long as diabetes remains under control. In this group local flaps are notoriously unreliable because microvascular damage is present in surrounding areas (see chapter 9 on wound healing).
f. What is probably the standard example of a pressure sore is one which occurs in a quadriplegic or a paraplegic where both muscular paralysis as well as loss of sensation co-exist. These patients may also have involvement of the urinary bladder and recto-anal dysfunction. The following description mainly concentrates on treatment of pressure sores in this category.
g. The healing of pressure sores in the paralysed is adversely influenced by the fact that the vascular network has become static, having lost its autonomic control. In normal circumstances the lack of blood supply during periods of intermittent pressure will be compensated for by hyperaemia during the time the pressure does not exist. The absence of this natural sequence will not allow good granulation to form around the cone shaped ischemic area. The incriminating bone now gets surrounded by fibrous tissue and the fibrous folds enclose synovial like fluid and this area is then called a bursa.
h. The above pathology of the pressure sore determines the rationale of treatment and therefore includes the excision of the offending bone, a wide area around and including the bursa and also the poorly epithelialised cone of the pressure sore, leaving behind a crater which shows good vascularity. In order that thorough excision is done, the procedure borders on the radical and the surrounding tissue filled with vessels which will not contract in a normal manner can bleed quite heavily and a blood transfusion might be needed. Infiltration with saline adrenaline and the use of a cutting cautery will help. The procedure, though done in a painless area, can occasionally invite shock because the paralysed part of the body has poor compliance vis-à-vis loss of blood and fluids that occurs during surgery. It is advisable therefore to do the procedure with a secure airway and light anaesthetic agents. In any event, close monitoring is very essential.

i. It is generally possible to estimate the size and depth of the crater that your excision will leave behind and if the crater is deep, a musculo-cutaneous flap is usually employed. For shallow craters, a bulky skin flap or a fasciocutaneous flap will suffice. In any plan for any kind of flap it is ideal not to create a secondary defect but should this be inevitable, the plan must be such so as to create a defect in a non-pressure bearing area. Such a defect need not be closed primarily with a skin graft but can be deferred for a few days later.

A large transposition fasciocutaneous flap with the added advantage of perforators entering it to close an ischial pressure sore after excision of any offending infected bone. Notice that the surgeon has used the flap itself as a donor area for a split skin graft.

A large sacral sore first debrided and then covered with local VY advancement flaps.

Photographs courtesy: Parag Sahasrabudhe from Pune.

5. While there have been occasional reports where some flaps have shown greater durability than others for pressure sores in non-sensate areas, the odds are generally stacked against such an outcome. An individual with major paralysis with loss of sensation is a formidable proposition to look after and requires a proper rehabilitation and caring centre. It’s a huge burden on the individual, the family and the state and though in the developed world such facilities exist almost free of charge, the conditions of these hapless victims in our country are pitiable. It is rare that a plastic surgical unit is proximate to a rehab centre even abroad and it so happens that the plastic surgeon is only casually in contact with the patient at the time of the treatment of the pressure sore. After discharge unless the rehabilitation and the care is good, what with the possibilities of debilitating urinary infection, ano-rectal problems and depression, these areas remain vulnerable to repeated ulcerations and can become a frustrating experience. Repeat surgeries are not uncommon and the plastic surgeon must do his best during the time that he is treating the patient.

Chronic Venous Ulcers of the Lower Leg

9. In the past there seemed to be a fixed population of intractable ulcers around the ankle which attended the out patient clinic or were admitted to an indoor facility in a plastic surgical unit but they now seem to be reducing in numbers. This might have something to do with the development of vascular surgery as a speciality.
10. With improved vascular imaging, both indirect (dopplers with ultrasound) and direct (radiological contrast studies) and greater possibilities to access the lumens of peripheral arteries, a small percentage of the so called venous ulcers are now proving to arise out of arterial insufficiency, and a fair percentage of these can be cured by way of vascular interventions and revascularization (atherectomy, endarteriectomy, angioplasty and stenting). While it is sound clinical medicine to palpate the peripheral pulses in the leg, the presence of such a pulse may not be enough to estimate the amount of flow. Findings of a feeble or reduced pulse are merely subjective impressions and in any long standing ulcer in the lower leg, some objective evidence of the volume of arterial flow needs to be obtained. Should there be a block in the arterial side, the treatment of this block must remain a priority before veins become the focus of investigation and treatment.
11. It is assumed while writing this section that the traditional methods of treating such ulcers with rest, elevation, bacterial cultures and suitable antibiotics, compression bandages, as well as biological dressings are being tried and will continue to be implemented as the arterial and venous systems get investigated and treated.
12. Venous ulcers are caused by venous hypertension in the superficial saphenous venous system. This system supports its column of blood against gravity by a succession of unidirectional valves along its length, ending near the sapheno-femoral junction, which too has a valve. These valves open in the cephalad direction. The blood from this system also gets drained to a deeper venous system in the calf muscles which, because of their pumping action, create a negative pressure from time to time within them. This drainage is effected via numerous short veins which pierce the deep fascia and are therefore called perforators. The valves within these perforators open towards the deeper system of veins. Any incompetence in either the vertical or the transverse perforator system leads to stagnation of blood in the superficial system leading to venous hypertension. Age has an important bearing on the incompetency of valves. The incompetence of the perforating system may be inherent or can happen following thrombosis of deeper veins which, when they get recanalised, () leads to holes being punched indiscriminately in the valves. Deep vein thrombosis of any duration also means that the drainage into them from the superficial system gets choked up. At the present time treatment of established deep vein thrombosis is not possible by any surgical method but early diagnosis can prevent its spread with the help of life-long treatment with anti-coagulants.
13. More important from the plastic surgeons’ point of view is how venous hypertension leads to ulceration and the consequences of this chronic ulceration locally. Soft tissue has poor tolerance to the extrusion of all intra-vascular substances contained in blood. This leads to irritation and inflammation and molecular necrosis. But, unlike in other parts of the body, here the process of healing is prevented because the extrusion persists and the venous stagnation will not allow proper scavenging of the products of inflammation. Local inflammation may lead to lymphatic obstruction as well. Chronic ulceration leads to scarring in the bed of the ulcer as dermis is slowly destroyed together with the sparse fat and, to add to the difficult situation, most of these ulcers are located in areas where bones and tendons are placed subcutaneously with only fascia intervening. In older, infirm people or diabetics there are additional factors which will retard healing.
14. While the standard surgical maxim states that removal of a cause should allow automatic healing, at least in some cases ulcers following both arterial obstruction as well as venous hypertension cannot follow this rule because of the scarring that has occurred in the bed of these ulcers during their chronic phase. The apparent healing by a way of tenuous epithelialisation is also vulnerable to trauma because of the ulcer’s location in the lower leg.
15. Therefore if the ulcer persists even after the arterial or venous cause has been properly treated by the concerned specialists, and the conventional treatment mentioned in point 3 does not succeed in healing the ulcer, it should preferably be biopsied to rule out a malignancy. Assuming this is negative, some form of skin cover can then be deemed to be necessary.
16. These wounds rarely ever granulate satisfactorily on their own, and their preparation for split skin grafting usually requires scraping or tangential excision or a formal excision up to some depth and also beyond the ulcer because the capillary network in the scarred area will have been lost through thrombosis. Even then the bed might remain unreliable and recourse might have to be taken to including normal skin by way of wide excision for a more reliable take of the graft. The graft on the original site of the ulcer then has the advantage of bridging from the graft put on the unaffected excised area.
17. Empirical evidence suggests that patients treated adequately for venous ulcers both by way of surgery on veins as well as proper skin cover continue to need elastic support to the legs for the rest of their lives with graduated compression stockings.
18. Only very occasionally, when the ulcers are deep with exposed bones and tendons with little hope of granulation creeping over these structures, flap cover becomes necessary. But while planning a flap the following facts need to be considered.
a. Venous ulcers are common in the elderly patient and there might be concomitant arterial disease and deficiency which requires to be looked into before skin cover is finally undertaken.
b. In several of these patients, if stripping and/or ligation or laser ablation of perforators has been performed, venous drainage may not be ideal.
c. Varicose veins are not infrequently bilateral and there might be problems in the veins of the contra-lateral leg including incipient changes in the skin. It is also likely that when a flap is borrowed from this area the defect created and now covered with a split skin graft may be vulnerable to ulceration over the years.
d. A flap positioned in an area of less than ideal drainage and/or arterial supply will not have a sturdy long term existence.
19. Once these conditions are borne in mind, a free flap, a cross leg flap or a turnover flap can be planned. Other local flaps have poor results in this area.
The author is grateful for the inputs given by Paresh Pai, a vascular surgeon from Mumbai for this chapter.

Treatment of Wounds – Repair and Reconstruction (Part 2)

1. Notwithstanding what has been said in the last paragraph of part 1 of this chapter there will be situations where a flap can save a life. example,
a. When a part of the brain bulges through a defect in the skull and is oedematous and does not have any skin or meningeal cover, the situation can lead to a serious infection followed by a fatal outcome. An oedematous brain is best not covered by anything rigid (bone or a metal mesh) and the situation demands a flap cover preferably from the adjacent scalp if available or by a free flap.
b. An exposed lung or heart with injuries to ribs with loss of skin and paradoxical respiration needs a flap cover after the ribs are stabilized. This restores the pleural space and averts further dire complications. A latissimus dorsi flap from the same side is a convenient option.

An example of a lateral chest wall defect including loss of bone treated with a local latissimus dorsi flap. This case is not traumatic in origin but the photographs are included because an identical post-traumatic situation will need a similar cover.

Photographs courtesy: Parag Sahasrabudhe from Pune.
c. After repair of major vessels for e.g. the carotids following gunshot wounds where the repair is done by direct suturing, vein grafts or a prosthetic graft but where the skin is shattered, contaminated and devitalized, a flap will help heal the vascular repair, restore circulation and reduce the overall chances of a blowout. A delto-pectoral flap can be a good choice for this site.
2. There will be situations where major post-surgical complications will threaten life or a repaired part. Here flaps can be of great help. examples,
a. A sternal dehiscence after a sternotomy for cardiac surgery can threaten life or mar the result of surgery. The condition of the patient permitting, a quick re-fixation of the sternum with resuturing of skin is the first option. But should the skin be suspect, its excision followed by a pectoralis major musculocutaneous flap based on a branch of the axillary artery away from the zone of sternal separation can avoid a catastrophe.

A. Infected sternal dehisons following open heart surgery. B. Debrided tissue including ends of ribs and cartilage. C. Indigenous VAC appliance has been applied. D. Pectoralis major flap can be seen moving in to the wound. Notice near the shoulder its attachment has been cut from the humerus yet preserving its blood supply which enters it about its middle. E. For the lower part of the defect the omentum has been brought up from the abdomen. F. The infected wound is now fully treated with vascularised tissue. G. Final result several weeks later. Skin has been sutured primarily.

Photographs courtesy: Parag Sahasrabudhe from Pune.

b. A repair of a major artery with a vein graft or a prosthetic graft as a planned procedure (for e.g. in the groin, thigh, popliteal fossa, neck or the axilla) can undergo an early or late complication because of infection and the skin might give way, become oedematous and unreliable. A local flap based on vessel or vessels arising proximal to the site of repair can secure the wound and give some chance for the vascular repair to succeed and save a limb. In the groin when the femoral artery is involved, a flap based on the deep inferior epigastric artery, a branch of the external iliac will be a good choice. As one goes lower down in the inferior extremity such flaps might become more difficult to find and release incisions on either side of the wound up to and into the fascia may allow a satisfactory closure of the wound.
c. When a major implant in the joint gets exposed post operatively, it’s only chance, if any, for any long term trouble free retention is if a flap is used to cover it quickly. Almost always, secondary suturing of such a wound will not help. Here too a local flap can be useful. For example, a gastrocnemius muscle flap for an exposed implant in the knee joint.
Comment: The plastic surgeon should be aware that most of the patients in this group may be on anti-coagulants.
3. With the advent of free flaps in patients who are stable and there is time to deliberate and time a flap, the choices have grown manifold. The old dictum that a local flap when feasible should be preferred over a distant flap (free or otherwise) now really holds true only in the area of the face and the scalp, because the nature of the facial skin with or without hair cannot be matched by any distant flap and in the scalp hair is of paramount importance. In both instances therefore the best use must be made of the available skin and this is where tissue expanders are most frequently used.
Comment: This is also the genesis of a full face transplant.
4. For other reasons for e.g. in reconstruction of the breast, the use of a latissimus dorsi flap or a lower abdominal flap based on the rectus muscle have been abandoned to a great extent because of scarring and the need to bolster the abdominal wall with a mesh where the rectus is used. Both flaps mentioned above are adjacent if not strictly local flaps. Instead the bulk of the lower abdomen together with the overlying skin based on major perforators of the inferior epigastric system are harvested as a free flap to reconstruct the breast.
5. Generally any local flap in the extremity means additional scarring in visible parts. Local flaps based on perforators are ingenious but patients might demand a free flap (could be based on a perforator) from a generally hidden part of the body.
6. In an athlete a local gastrocnemius flap for a tibial cover may not be fair to his future rehabilitation and his request for a distant free flap from a non-functioning area would then be legitimate.
Comment:
Microvascular free flaps are now being done routinely across specialities and the time may not be far when robots will be used for microvascular repair, such repairs might be done by technicians and lastly if a coronary vessel can be dilated and its patency maintained by a stent, surely such an innovation may be feasible in free flaps.
7. The introduction of free flaps has meant that more reliable, one stage sensate flaps can now be performed. While theoretically they should be better, at least from the point of view of protective sensations (if not finer sensory modalities), the jury is still out on what is the best treatment for e.g. in a denuded heel, the commonest site for which a sensate flap is used. Ideally the medial plantar flap (based on a branch of the posterior tibial artery and containing the medial plantar nerve) from the concavity of the middle third of the foot should be transposed to resurface the heel when such skin is available and when most of the soft tissue over the heel is missing and bone is exposed. But this might not always be possible. The choice is then between a staged cross leg flap, carrying the sural nerve, a free musculocutaneous flap, a free muscle flap covered with a skin graft or even a skin graft alone when a thin layer of viable soft tissue over the bone is nursed with careful dressing till granulation tissue appears. Long follow-ups with all the above methods have shown some success. The one common feature associated with all these flaps is hypertrophic cornification at the junction of the flap and the normal skin. This occurs very rarely with a medial plantar flap which remains the first choice if available. This cornified tissue needs to be carefully excised from time to time.
Comment: In the past a cross-finger flap was the commonest procedure performed for loss of skin and soft tissue in the fingers. They are not sensate flaps. Yet they almost never show any ulceration even in manual workers.
8. The choice particularly of a free flap certainly depends upon to a great extent on what flap the surgeon is most familiar with. Most surgeons will develop expertise with three or four types of flaps. Bulk is always an issue. Sometimes it is needed to fill a space or a cavity in the bone and at other times a bulky flap is avoided to prevent an ugly lump. On the subject of healing of infected cavities, though there have been papers on comparison of random pattern flaps and free muscle flaps in animals, showing the superiority of free muscle flaps; no human trials are available because they are not possible. In any event random flaps are now rarely done and it seems unlikely that a fasciocutaneous flap will have a dramatically lower blood flow than a muscle flap. Traditional anecdotal wisdom for whatever it is worth seems reluctant to divide flaps as superior or inferior in its healing power. A flap that succeeds fully is always a good flap and only good can come out of it.

Treatment of Wounds – Repair and Reconstruction (Part 1)

1. A clean incised wound should be closed as soon as possible after irrigation with saline or a proprietary anti-bacterial solution.
2. A contused, lacerated wound needs a sharp, adequate excision of its edges prior to closure because the contused skin might have been devitalized.
3. Except in very superficial wounds dermal approximation with a durable suture (with a life of three to six months) helps prevent a broad scar and a good dermal opposition means the outer sutures can be removed early.
Comments:
a) The introduction of biological glue and of sterile strips applied across wounds have changed the way the outer layer of the wounds are treated.
b) The introduction of staples in closure of surgical wounds including for flaps after they have been set into defects has reduced operating time and surprisingly crude though the staples might look, the incidence of cross-hatch marks has been almost completely eliminated. The staples do what a ‘she cat’ does to her kitten as she carries them with her teeth. The staples hold the skin at some distance from the wound without puncturing it to any appreciable depth.
c) When wounds occur in unfavourable directions i.e. across Langer’s lines they are usually closed without any primary re-adjustment of the suture line e.g. by a z-plasty, indicating that conspicuous scars are not inevitable in such a situation.
d) Superficial burn wounds heal splendidly with a variety of proprietary dermal substitutes. However when burns occur around fingers in children, when it becomes difficult to wrap the dermal substitute around them, a dressing material dipped in an antibacterial solution wrapped around the fingers secured with a dry, firm bandage can be left alone for several days till it falls off by itself when it becomes loose.
4. In large wounds where the patient is brought in a critical condition, the treatment of the affected systems takes precedence. Cardiorespiratory resuscitation, securing of an airway, treatment of sucking wounds in the chest and volume replacement begin first. If the wound is bleeding, pressure or ligatures or in cases of lacerations of major vessels, application of atraumatic clamps, removal of mangled, crushed and irreparable parts of the limbs is all that should be done as resuscitation begins. Fractures in major bones are assessed, splinted and a plan for their fixation charted out.
5. Once the patients start getting stablised, the wounds are inspected in some detail, repair of major vessels might have to be performed quickly if the viability of the limbs is threatened. If a formal secure skin cover over these vascular repairs is not feasible, local soft tissue or adjoining muscles are used to cover the repair as a temporary measure. Surface cultures, or cultures from dead tissue are sent, antibiotics are used in consultation with other specialists and debridement can begin.
6. Debridement is an artful craft where the cutting instrument must remain within the obviously dead tissue and progress is then made towards what is certainly normal and then stopped when there is evidence of some bleeding. A temptation to chop off tissue en masse is avoided. Serial debridement is always preferred to avoid any excess and also because, as the wound evolves, more dead tissue becomes apparent. Bed sores in acutely ill patients should not be attacked surgically and should be dressed till their full extent is realized.
7. At this stage if there are fractures, they will be stabilized if the patient’s condition permits and the plastic surgeon hopefully should participate in the discussion as to the nature of stabilization because then plans can be made for a flap cover.
8. Wounds that will need skin cover belong to three categories. First, a clean wound in a stable patient which can be covered soon after admission (within first 48 hours). In the second category, a similar wound in a patient who remains critical but stable e.g. on a respirator and a vasopressor drip, is a matter of judgment, choice and certain philosophy. In most units now skin cover is achieved in order to close the wound and reduce any burden that the wound may have on systemic recovery. This can be done with regional blocks or with infiltration of a large dilute solution of local anaesthetics for surface analgesia and can be done in stages over days. But if this is difficult, homografts are applied to achieve the same result to temporarily tide over the situation. In the third category, the wound is dirty, continues to undergo necrosis in its bed and the situation may or may not be complicated by the general condition of the patient.
9. Under these circumstances,
a. The wound must be inspected at least once a day when debridement of dead tissue is undertaken
b. Irrigation should be done with saline or with a proprietary antibacterial compound after instillation of hydrogen peroxide
c. In limbs a simple air pump can be used to create bubbles in an antibacterial solution in a bucket and the limb is immersed in the bucket for up to half an hour, which will help in giving painless, gentle lavage and reduce the bacterial load.
d. A forceful, power driven jet lavage system is now available to clean wounds but it can be used only under anaesthesia.
e. Hyperbaric oxygen will help wounds not only by increasing cutaneous oxygen saturation but is known to help critically ill patients in general.
f. Even in sick patients, suction appliances can be used on any part of the body to clean up the wounds without in any way interfering with the measures that are taken to stabilize patients.
g. The Edinburgh University solution, Eusol, is still used and has had several proprietary substitutes including a solution in which oxygen has been forcibly pumped (short shelf life) but this solution has had its marketing ups and downs.
h. Enzymatic preparations which dissolve dead tissue are available as ointments or in proprietary dressings but have not been fully proved as effective in cleaning large wounds.
i. Some wounds which appear indolent in spite of all the above can improve with tangential excision if some form of analgesic and short acting anesthetic is permitted even if the patient is on a respirator or on dialysis.
10. The improvement in the wound is also greatly dependent on the condition of the patient. For example, a patient with a major brain injury who is sustained on a respirator, a patient who has undergone a major abdominal surgery involving for example a liver resection or a major bowel resection followed by an ileus, or has multiple organ failure as a result of an untreated hypovolemic shock in the initial phase are poor candidates for any improvement of their wounds. It is best that nothing adventurous is done on these wounds under these circumstances. Here expensive biological dressings are a waste of money and effort during what has been described as the catabolic phase of the wound and these applications are just devoured by the multiplying bacteria that grow in the wound. Ordinary dressings will do equally well.
11. This chapter deals mainly with preparation for split skin cover in large wounds. Any situation where two or three areas require a flap, in one or both limbs or other parts of the body, must wait for some time for final treatment. To give an example, a large defect over the lower femur, a repaired popliteal artery, an exposed knee joint together with an exposed muscle mass in the calf and exposed tarsal bones will classically need multiple flap covers but here prudence will be needed because the procedures might destabilize the patient. Each case is dealt as a problem in itself.

Each individual case however must be judged on its own merit. In this case an obese patient was transferred secondarily to a speciality hospital following a vehicular accident and was running fever and had critical injuries over the tendo-achilles and the calcaneus and a part of the heel was exposed which required flap cover. After stabilising the patient the critical area – above left and middle, was covered with a free anterio-lateral thigh flap from the opposite limb – upper right, and then the wound on the front of the foot was allowed to improve – below left and then split skin grafted – middle and right below. Photograph courtesy: Parag Sahasrabuddhe, Pune.

12. There are two parts of the body where non-biological substitutes are useful and can save life where a flap is needed but is not feasible. In the anterior abdomen a large defect with bowel exposed can be temporarily sealed by a sheet made of polytetrafluoroethylene (PTFE), which then can be dressed till granulation can grow from the sides. An ordinary polyethylene sheet covered with a vaseline gauze and dressings, though inferior in quality, has been used with similar results. In the skull the loss of bone and scalp over a large area with the brain exposed can be covered with a proprietary dural substitute and the bony defect can be temporarily obliterated with a titanium net or a special cement, measured and moulded and then fixed to the rest of the bone with wires.
13. What flows from the above points is that decisions made in the treatment of large wounds need to be deliberated. The deliberation more often than not has to be conducted between various specialists. When major flaps are needed in physiologically unstable patients, they are at best left to a later date by when the patient will be in a position to undergo surgery under adequate anaesthesia. However split skin cover will have a stabilizing effect on the patient, and can be performed relatively quickly and easily.

The how and why of flap failure

1. The success or failure of a flap depends upon how it is designed.
2. An axial flap has a certain territory. This territory has also been called an angiosome and can include skin, fascia and bone.
3. At the watershed area between two territories of adjacent flaps lie small vessels which will dilate if the area is delayed (see chapter 12). This delayed area can then be included after a certain interval in the original design of the axial flap. The area of the skin over the shoulder, for e.g., can be incorporated in the delto-pectoral flap if the skin over the shoulder is delayed in the axis of the intercostals perforators which run across the chest.
4. If planning is poor, and extra territorial tissue is included in the flap without a delay that part of the flap will die. As it happens, more often than not, this part, farthest from the base is the most critical in the reconstruction and the purpose of the flap may not be achieved. Not only that, there may be a deleterious effect on the surviving part of the flap because of the necrotic tissue in the dead part of the flap if it is not removed quickly.
5. In a random flap where a proportion of the one (base) to one (length) is maintained the flap succeeds in most parts of the body. However empirically this one-to-one rule can be transgressed in some parts of the body like the face where blood supply is abundant. A superiorly based naso-labial flap of outrageous dimensions, such as 1-4 or 5 will survive without a specific vessel because numerous vessels cris-cross the face in all directions.
6. When flaps die their death is somewhat dependent on their type. A ‘free’ axial pattern flap either survives completely or dies fully depending upon whether the microvascular anatomosis is patent or not. If such an anastomosis is blocked the flap can still be salvaged after the flow is re-established across the anastomosis which should be done in a short time (usually not more than a period of four hours).
Prabha Yadav and her group from TMH Mumbai add that the salvage of a ailing microvascular anastomosis should be treated as an emergency because the chances of flap salvage are inversely proportional to the time elapsed from the advent of thrombosis.
7. Any delay in establishing a patent anastomosis is dangerous. A dying flap takes recourse to anaerobic metabolism in order to survive. But the anaerobic state has certain consequences such as an increase in the number of polymorphonuclear cells which exhibit a marked tendency to adhere to each other. The anaerobic state also gives rise to harmful derivatives of oxygen called free oxygen radicals and superoxides. There is a built in mechanism in the anaerobic tissue to overcome to some extent these two events. If perfusion gets re-established suddenly after a few hours, this mechanism is overwhelmed by a flow of fresh blood, the leucocytes get pushed into the capillary network and the capillary web gets clogged leading to more production of oxygen free radicals and the flap will die in a very short time. The event horizon of how soon this reperfusion injury will occur is not clear. A reperfusion injury is commonest in replanted limbs and large muscle flaps are more vulnerable in this regard than cutaneous flaps.
8. A clogged capillary network is beyond any remedy and there is very little or no evidence that a pharmacological intervention will help. In fact there is no unanimity about any anti-clotting agent helping anymore than saline when the anastomosis is in progress. The use of a heparin solution being sprinkled over the site of anatomosis has an empirical basis and its use is more a tradition than an act based on science.
9. The best time to save a free flap is on the table by waiting to see if the anastomosis is patent by maneuvers such as gentle pressing on both the arterial and the venous side, the latter more carefully, delicately and frequently because the venous side fails more often in view of its non-pulsatile flow.
10. The best practice is to leave the site of the anastomosis open and to suture the rest of the flap and wait. Occasionally even a tight suture might impede the flow and can be modified to reduce any effect that it may have on the circulation. The best practice is to leave the skin over the anastomosis open.
Prabha Yadav and her group from TMH Mumbai add that the lie of the anastomosed vessels should be checked in different positions particularly in the head and neck. If the anastomosis is placed over a joint, a kink or tension in the anastomosis can be avoided by proper splintage leaving the flap area open for observation. Also drains left behind under the flaps should be carefully placed so as not to impinge on the anastomotic site.
11. Notwithstanding a variety of very sophisticated methods being available to judge the viability of a flap, the pin prick test, though its interpretation is subjective (the colour of the blood that oozes out), continues to be fairly reliable for a vast number of cases. A failure of the anastomosis on the arterial side usually results in a white flap (instead of pink or pink-brown). A venous outflow block increases the percentage of reduced unoxygenated haemoglobin and the flap turns blue. On pin pricks therefore, a sluggish flow of blue or dark blood is seen. It is usually easy to identify a well perfused flap which on being pricked will reveal bright red blood flowing out. For obvious psychological reasons a surgeon might, because of wishful thinking, not admit to himself or herself that a flap is dying. A quick inspection of the anastomotic site after an adverse pin prick test is the best time for re-exploration. At this stage a dilute solution of heparin is frequently used to help to extract the clots from the vessels so as to prevent re-clotting.
Prabha Yadav and her group from TMH Mumbai describe a failed arterial anastomosis resulting in a shriveled flap due to loss of turgor and failed venous anastomosis resulting in a blue, dusky, bloated flap.
12. A flap is extremely vulnerable when a blood clot forms underneath. A snugly fitting flap, of whatever type has no place whatsoever for such a clot, nor for that matter even for its benign counterpart of an organizing seroma. The presence of a clot as it hardens (and it does) over a period of time puts an unsurmountable burden on the pressure head within the capillary network. This situation needs to be guarded against particularly when systemic heparin is used. If the defect over which the flap is placed has been debrided just prior to the placement of the flap, a very thorough haemostasis is crucial. The very nature of indications for flaps is such that many a time a bone is the base of the defect. A blood clot therefore can only press over its softer exterior (the flap). Even in staged flaps where a part of the defect remains open near the bridge of the flap, this clot can come to occupy the under surface of the flap by blocking the exit route early. An early diagnosis of such a clot and its release and extraction by removing a few sutures can dramatically alter the fate of the flap for the better. Occasionally the whole flap may need to be taken off, haemostasis achieved and then put back.
13. A blood clot is also known to release harmful oxygen radicals and therefore constitutes a double edged weapon. A clot that remains unrecognized is an excellent medium for organisms to grow, particularly because many indications for flap cover involve infected cavities which, a thorough debridement notwithstanding, are never really free of offending bacteria. An infected blood clot is like an abscess under the flap – not the best of the situations for a composite tissue which is recovering from a gross physiological insult only a few days earlier.
14. An axial or a random flap when cut on three sides becomes devoid of the bulk of its nerve supply. The local neurotransmitters therefore cause vasoconstriction as a protective response and this has maximum effect on the distal portion of the flap. Over the next couple of days in a properly designed and executed flap this gets reversed only if the base of the flap and the bridge (in a distant flap) remain in a state of ease. The base must be free of pressure, of dressings or a plaster or a splint (if used) and the bridge must neither be stretched nor rumpled on itself. The recipient site of the flap should ideally be higher than the base to aid venous drainage and the flap should not have any collection underneath. Any deviation from these conditions may adversely affect the return to normalcy from the early phase of vasoconstriction, particularly in the distal part of the flap.
15. A proper execution of the surgery itself is a matter of craft based on sound knowledge of anatomy and a familiarity with a particular procedure or flap. That as it may be, some flaps are more easily executed than others. A fascio-cutaneous flap in the upper or middle calf is a matter of an easy peel once the deep fascia is identified, cut and then fixed to the skin with stitches or staples to prevent separation. As opposed to this, in a groin flap where the vessel (superficial, circumflex, iliac) has left the femoral sheath earlier, and then travels in the fat between the two layers of the superficial fascia, the dissection needs to be undertaken carefully.
16. The same holds true of scalp flaps where the thin, innermost vascular layer of the pericranial tissue needs to be carefully preserved by identifying it because the defects in the scalp when flaps move are rarely ever amenable for primary closure, sometimes even after tissue expansion and will need to be skin grafted which will not be possible if bare bone gets exposed.
17. The nature of death of flaps is somewhat different for each type of flap. As mentioned earlier, a free flap belongs to the all or none category. It survives fully or can die quickly and in its entirety and has therefore no chance for revascularization from its bed in that short period. A random or an axial pattern flap moved locally or over a distance, particularly if it is thin and if the recipient bed on which it is put has even a modicum of potential for revascularization is at an advantage because within a matter of days cross vascularisation can begin. An axial flap unless it is very long or is based on skeletonised vessels also has a random supply at its base and therefore has a fighting chance to survive at least partly. A random flap with safe dimensions is the hardiest of them all but its dimensional restrictions mean its uses are restricted.
18. In an anecdote narrated to this author while this chapter was being written, about the preceding point, Prabha Yadav, the head of Oncological Reconstruction at Tata Memorial Hospital mentioned a case of an osteocutaneous (fibula) free flap transferred to the face, having survived for two weeks, then suffered a block at the anastomotic site in the neck due to a fulminating infection leading to sequestration of the fibula but the skin survived because by that time it had been neovascularised from the peripheral, facial skin.
19. Of the other factors that may adversely affect the outcome of flap surgery, long standing poor general health, atherosclerosis, diminished cardio respiratory function and an immunologically compromised patient constitute the standard candidates and they are not greatly different from the causes that adversely affect the take of a skin graft.
20. What stands out however is the habit of smoking, particularly if the habit has continued for several years, and though weaning prior to surgery is advisable, proper controlled scientific trials show that chronic smokers have a high rate of complications compared to non-smokers.
21. Seemingly adequate, but in fact histologically inadequate excision of malignant tumors also adversely affects healing of flaps and this is particularly so in cancers around the oral cavity where poor oral hygiene is an added factor and cannot really be improved prior to removal of the tumor.
22. A dead flap is best excised quickly. However, there is a rider to this rule in case of ‘non-free flaps’. This concerns what is perceived as a superficial loss after a few days. Such doubtful areas can be tangentially excised till the bed bleeds and then can be secondarily grafted. What is achieved can be quite remarkable because if the deeper tissues are already neovascularised and the graft takes, the original purpose of the flap is almost fully realized. Some months later the area can look quite unremarkable from the rest of the flap.
23. When a flap dies and is excised (even tangentially), it is best that the tissue is sent for a bacterial culture. Though not mentioned earlier, in spite of thorough debridement of recipient areas, if a bacterial culture has not been obtained at that time, and suitable antibiotics are not started, flaps can die due to infection because they are not entirely resistant by way of their own local, immune system.
24. This is particularly true in cases of trauma where a waiting period of two or three days is advisable after debridement and stabilization of fractures. There might be tissue in such a wound which is moribund but looks good to all outward appearances and dies in the period following debridement. A flap placed on such a tissue and sutured over it suffers doubly as it can be attacked by the infection already present and also has little chance of cross-vascularisation from this area.

Flaps are a vascular network

1. The bulk of our body develops in the mesoderm.
2. The mesoderm like all embryological tissue is a matrix to mean an environment or a substance in which a thing develops.
3. At an early stage this matrix is a syncytium which means a tissue with multiple nuclei but without well defined cell membranes.
4. In this tissue is laid a capillary network.
5. This capillary network is common to all tissues that are developed in the mesoderm simultaneously.
6. As differentiation progresses, muscles, tendons, bones, ligaments, capsules, synovial membrane, fascia and skin (dermis) partake of this capillary network.
7. As bulk is added, some parts of this capillary network coalesce to form blood vessels and the rest of the capillary network remains intact.
8. This development happens pari passu that is simultaneously or equally and hand in hand, across the body.
9. In vertebrates, for example, the development of the bony spine is accompanied by laying down of vessels on either side.
10. These form the main vessels of the body (for example the aorta).
11. Parts are developing simultaneously and the vessels that are laid in these parts are called internal vessels for e.g. iliac vessels.
12. The capillary network within individual organs for e.g. bone, muscle and skin also develop into vessels at the same time by a congregation of the capillaries already existent in the developing tissue.
13. When the heart starts to pump, a linked vascular architecture therefore is already present which has by then developed an arterial and a venous side.

14. The muscles and the dermis have by far the richest vascular network, the muscle for its high metabolic rate to support its mechanical actions and in the skin for its thermo-regulatory function.
15. As these two develop hand in hand, their shared capillary network has already resulted in a vessel or vessels which supply the muscle and then are linked to the skin via the fascia. These we call musculo-cutaneous vessels for e.g. an artery supplies the gastrocnemius (medial sural) and because the muscles’ network is connected to the skin, a musculo-cutaneous flap can be raised to include the muscle, the fascia and the skin. The muscle alone can also be lifted as a flap based on this vessel.
16. In the extremities where muscles are longitudinal and are arranged in compartments by way of septa made of fascia, an internal artery can get linked to the skin via this fascial envelope without going through a muscle. This arrangement is called a septo-cutaneous vascular network. This connects to the skin via a network over the surface of the fascia. For example, the saphenous artery emerges from the adductor canal (a septal canal) to run along the fascia on the medial side of the calf. We therefore can harvest a fascio-cutaneous flap and this can be used locally or as a free flap.

A standard superiorly based fasciocutaneous flap used to cover a defect on the anterior part of the leg with exposed bone.

Distal peroneal artery perforator perfused retrograde fasciocutaneous flap used to cover a difficult post traumatic scar ulcer on the lateral part of the foot.

Distally based fasciocutaneous flap based on a perforator of the posterior tibial artery for a lesion in the medial side of the foot.

Occasionally fascia together with the fat can be harvested while sparing the skin on top and then can be turned over for a defect and then in turn can be covered with a split skin graft.

Photographs courtesy V. Bhattacharya of Varanasi who has original work on the subject of Fasciocutaneous Flaps to his credit.

Comment: The advantage of a fasciocutaneous flap is that the branches of the perforator travel both superiorly and inferiorly and therefore an inferiorly based flap which is very useful for defects in the lower leg and foot can be harvested. Also as compared to a muscle harvesting fascia is (theoretically) less debilitating.

17. Occasionally, such a septo-cutaneous vessel will preserve its identity and run under the skin to supply a distinct area for e.g. the external superficial circumflex iliac vessel. This then is the basis of the groin flap which includes skin above and below the inguinal ligament.
18. In the leg itself the mesoderm which is to later develop as the fibula is connected to its immediate environment which is to develop into the muscles of the lateral compartment and share their capillary network. Out of this arises the nutrient artery of the fibula, a branch of the peroneal artery and the rest of the peroneal artery supplies the muscles. The fibula is a commonly harvested as a free bone graft with a muscular cuff at the point of entry of the nutrient vessel.

Upper left: Scarred healed compound wound over humerus. Upper middle: bone gap in the humerus. Upper right: Free fibular graft harvested. Below left: Free fibular graft fixed and simultaneous flap cover. Below middle: Healed with good union and restoration of movement. Below right: Radiological evidence of the union at both ends of the free fibula. Photographs courtesy: Mukunda Reddy and Srikanth from Nizam Institute, Hyderabad.

 

Samir Kumta from Mumbai adds that when the fibula is harvested in the lower two-third the nutrient artery may get sacrificed and the bone survives on the branches of the peroneal artery which constitutes its periosteal blood supply. The peroneal artery here being the main artery anastomosed to the donor vessel.
19. The iliac crest which is a flat bone gets branches from the deep circumflex iliac artery and then also perfuses muscles in the adjoining area as well as the skin. This is a direct branch of an internal artery (the external iliac) which perfuses a segment of the mesoderm which differentiates into bone and muscles and is usually used as a free osteo-musculo-cutaneous flap.
20. An interesting, useful and popular flap in the inferior extremity is the antero-lateral thigh flap. This flap draws its blood supply from a branch of the lateral circumflex femoral artery which first gives branches to the rectus femoris and the vastus lateralis muscles and then emerges from the space between them to perforate the fascia and supply a fairly large portion of the skin and the subcutaneous tissue. This vessel though classically septocutaneous in the end, also supplies muscles prior to its emergence through the fascia and is therefore interesting. This brings to the fore the difficulty of nomenclature such as septocutaneous, myocutaneous and perforator vessel flaps which is convenient up to a point but might be confusing if made too didactic. This flap is useful because it harvests a fairly large area of the skin with substantial subcutaneous tissue which can fill deep defects and is popular in India because the defect left behind can be easily hidden by most clothing that Indians wear. This flap is mainly used as a free flap.
Prabha Yadav and her group from TMH Mumbai add that the anterior-lateral thigh flap can be used with great advantage in defects of the lower abdomen, groin, perineum and the gluteal region as a local flap.

A. Malignant lesion on the left iliac crest. Area of excision has been marked. B. The area is excised. C. Lateral thigh flap is marked. A small incision for access to the pedicle of the flap can be seen. D. The flap is transposed to the excised area. E. The flap is sutured and the donor area has been closed primarily.

A purely random pattern flap is perfused by unnamed small vessels which are the terminal branches of one of the above systems.

A. A case of carcinoma of the penis with almost total amputation. B. Close up view of regional glandular metastasis in the groin. C. Defect after the metastatic lymph nodes are excised with overlying skin. D. The left lateral thigh flap has been marked for the ipsilateral defect. E. View showing both flaps in place. F. Flaps sutured where the donor defect has been closed primarily.

Photographs courtesy: Prabha Yadav and her group at the Tata Memorial Hospital, Mumbai

Addendum:  The December 2011 issue of JPRAS has reported a flap of the bare skin with a specific perforator. The skin is thin enough and therefore suitable for reconstruction for microtia and external ear atresia. The same issue also reports a thin osteo-periosteal flap for reconstruction in a finger which in turn has been skin grafted. The osteo-periosteal flap is also perfused by a very minute specific blood vessel. In both cases microvascular technique has been employed.

Flaps: General Principles

1. A flap is a piece of living composite tissue which carries with it its own blood supply and is used to close a defect or address a deficiency. When such tissue is shifted locally it is called a ‘local flap’. A flap can be transferred to a distant site, remaining attached at its base (or pedicle), which is the source of its blood supply. Its transferred part is allowed to establish vascular connections from the recipient area over a period of time (usually two to three weeks) after which the pedicle is divided. This is a staged distant flap. In the third category, the whole of the flap is lifted off its moorings with only specific blood vessels which supply it and then these blood vessels are anastomosed to blood vessels in the recipient site to restore its circulation these are called ‘free flaps’. Because these vessels might be small and require a microscope for their anastomosis, these flaps are frequently referred to as ‘free microvascular flaps’. The restoration of the circulation of these flaps needs to be established quickly in a matter of hours.
Prabha Yadav and her group from TMH Mumbai pertinently point out that an island pedicled flap with its own source vessel in its base is neither a free flap nor a distant staged flap or classically a local flap and forms a separate subset which Visweswar Bhattacharya rightly calls a single stage regional flap.
2. The words “composite tissue” imply more than one layer and traditionally the tissues so moved as a flap consisted of the whole of the skin and at least a part if not the whole of the subcutaneous tissue. In the last four decades the composite nature of the flaps has changed and a flap can now include in addition to skin and subcutaneous tissue deeper structures such as fascia, muscle and bone. Exceptionally it may also carry tendons and nerves. A flap of adipofascial tissue without skin and a flap of fascia alone have also been described. A muscle flap without its cover such as fascia and skin is now a fairly common procedure. A part of the colon transferred to reconstruct the vaginal passage or a segment of a small bowel used to reconstruct the oesophagus are also flaps because they are composite in nature and their circulation is either maintained through their pedicles or restored by microvascular anastomosis.
Visweswar Bhattacharya from Varanasi adds there can be combination of flaps e.g. Adepofascial or fascial extension of fasciocutaneous flap to fill up the contour defects. There could be also fasciocutaneous extension of myocutaneous flap.

Samir Kumta from Mumbai suggests that the word ‘flap’ should be used only when the transferred tissue contains skin.
3. Because of its composite nature and its intact blood supply the flap is a net addition to the area where it is transferred. In other words the flap is a living thing and adds value within hours after its transfer. This is in contrast to a skin graft which must borrow from the recipient site for its survival.
4. What flow from the above are the indications for flaps.
a. To re-establish the anatomical and physiological integrity of a part (e.g. en bloc reconstruction of a head and neck defect created after surgery for a malignant tumour).
b. To cover, protect and nourish vital parts of the body for e.g. bones, joints, tendons or major vessels or nerves which are exposed.

On the left a large defect on the scalp with necrotic tissue and exposed bone which might sequestrate over a period of time if not covered with a flap. On the right, an adjacent transposition flap to cover the defect the flap is raised without the peri-cranium left intact and that is why a graft on the residual defect has taken fully. Photograph courtesy: Vinita Puri, KEM Hospital, Mumbai.

c. To cover and protect vital organs of the body for e.g. the brain,  viscera or the eye.

Above left : a severe injury over the scalp with mutilation of the upper eyelid and avulsion in situ of the lower eyelid. Above right : a free anterio-lateral thigh flap performed to cover the exposed bone of the skull and also to cover the upper eyelid the constituents of which were repaired. Below left : late post-op showing that the patient is having adequate levator action. Below right : the patient is able to close his eye and is saved from the possibility of exposure keratitis. The repaired lower lid has survived and is functional. Comment: The flap will require to be de-fattened. Photograph courtesy: Vinita Puri, KEM Hospital, Mumbai

Also see photographs in the chapter on Burns Part 4 : Electrical Burns for a similar indication.

d. To improve function for e.g. as in a flap which carries a sensory nerve or a transfer of a muscle to improve the results of a facial palsy or create a sphincter for e.g. anal sphincter via a Gracilis muscle flap.
e. To improve appearance by substituting the exact tissue that is missing in a defect.
f. To replace a dense adherent scar where several layers of the integument have healed by secondary intention leading to deformities or loss of function or instability.
g. To achieve cover in this manner which will allow a later surgical access to a part which needs repair or reconstruction.
Please see photographs of a case of Electrical Burns in the chapter ‘Burns Chapter 18, Part 4′.
h. To create living, durable, tubular structures e.g. reconstruction of oesophagus or a vaginal passage.

1: Total laryngopharngectomy for post cricoid growth, 2: Pharyngeal defect from base of tongue to upper end of esophagus, 3: Forceps showing the upper end of esophagus, 4: Planned length of jejunal harvest, 5: Jejunal segment – mesentry dissected and showing the pedicle, 6: Jejunum flap inset done showing the proximal and distal anastomosis, 7: Monitoring paddle of jejunum with the mesentry in continuity and showing contraction, 8: Immediate post op showing the monitoring paddle and the permanent tracheostomy, 9: 10 days post-op (before the division of monitoring paddle), 10: Late post-op, 11: Barium swallow showing pharyngeal continuity and no leak (done between 10-14 days). Photographs courtesy: Prabha Yadav, Tata Memorial Hospital, Mumbai

i. To heal wounds with major net tissue loss across joints or vital parts where mere epithelialisation is likely to undergo repeated breakdowns and affect function. This indication also includes areas which have been irradiated or where extravasation of a toxic chemotherapeutic agent has caused multi-layered necrosis.

Defect in the perineum, the area was irradiated for a malignant tumour of the anal canal extending into the rectum closed with a gracilis musculocutaneous flap. The photographs illustrate more than one indication for performing a flap.

j. In contractures of whatever etiology where a skin graft might succeed yet a flap will give better aesthetic or long term results.
k. To plug holes in vital structures which cannot heal by themselves for e.g. a broncho-pleural fistula or a sizeable fistula after repair of a hypospadias (a hypospadias cripple) or a fistula in the hard palate or a vesico-vaginal fistula.
l. All flaps also improve the local immunological status of the area to which they are transferred and infected cavities are frequently controlled and cured by filling them with flaps. This is a concurrent indication in many situations.
5. Every incision that a surgeon makes is a step towards the creation of a flap. When the incision is deepened and then undermined for example with a C-shaped retractor in a right para median incision on the abdomen, the incised undermined flap anterior to the C-shaped retractor loses some of its blood supply which enters it from its bed (in this case the perforators from the anterior rectus sheath which envelopes the rectus muscle). However such a flap will survive even if it is undermined extensively because it receives blood supply from the inter-costal, sub-costal and lumbar vessels from its lateral side. Contrast this with a vertical incision in the lower-one third of the leg over the tendo-Achilles. If in order to get access to the tendon to repair it, the skin is undermined even for three or four centimeters the likelihood that it might necrose after closure of the incision is much higher than for the abdominal incision described above. What necroses is an undermined flap of skin because its loss of blood supply from its bed was not compensated from its other three sides.
6. The etymology of the word ‘flap’ has antecedents in the wing of a bird (because it flaps when it moves, flapping of a wing). That gives a good picture of what a standard flap is; a base and three free sides. In fact a local or distant staged flap is usually cut on three sides and lifted off its bed and will certainly be jeopardized if its fourth side is unable to perfuse it adequately. Bearing this in mind, by a general rule, a flap was considered safe in most parts of the body if the base of the flap was equal to the length of the flap. This rule did not actually investigate the ability of the base to perfuse but was arrived at by experience and assumed that the random (not specific) blood supply from the base was enough to perfuse the flap and allow it to survive. But a flap of such a dimension had limitations in moving locally and in a staged flap, not much of its surface area could be conveniently attached to the prospective recipient area.
7. It is on this background that we need to view the history of making of flaps. As it happens the two crucial events in this regard happened nearly 2,600 years apart. According to tradition, when Sushruta (600 BC) placed a broad leaf, with a very narrow stalk on the forehead (as a pattern), the stalk near the medial end of the eyebrow and over the nose and cut his flap and rotated it through 180°, to repair a ‘cut nose’, according to literature, he had said in Sanskrit, “it (the flap) survives by continuity”. Sanskrit aphorisms are too brief for us to be able to fathom what Sushruta thought or meant to convey but the word continuity obviously meant continuity with the rest of the body. This flap’s dimensions were outrageous by modern standards of only 60 or 70 years ago. Then came Milton who in 1970 showed by cutting flaps of varying lengths and also of varying breadths on the backs of pigs, that what mattered was what was contained in the base of the flap and not how broad or long it was. If the base included a segmental vessel, the flap could be cut to a considerable length even if the base was very narrow, as long as the flap included the vessel. Milton, who shared his name with the well known poet, was a poet himself in that according to an old Indian tradition the word ‘poet’ in Sanskrit is ‘kavi’ who is supposed to be a visionary and it is said of a poet that “what the sun (‘Ravi’ in Sanskrit) does not show, a ‘Kavi’ will see”. Milton saw things on the back of a pig.
8. Milton’s work explained how the delto-pectoral flap had been successful. It contained numerous blood vessels that ran across the chest to the shoulder having emerged from the inter-costal spaces. Soon the groin flap based on the superficial, circumflex, iliac artery was described and a successful transfer of muscle with its blood supply intact was published to obliterate and close a bony cavity.
9. While all this appears reasonable on hindsight, in the world of science, there is many an offshoot pursued by very talented and industrious individuals which fall by the way side as momentum gathers in one particular direction. The tube pedicle was one such effort, in which a random area of skin and subcutaneous tissue of a sizeable dimension was cut only on two sides instead of three and tubed on itself to allow blood vessels to orient along the axis of the tube. Then after a certain interval one end of the tube was cut, sometimes after slow strangulation to modify and to allow the blood to flow only from the other end, then the flap was cut and the cut end was put on the desired recipient part and reconstruction was achieved in further stages. Several variations of this maneuver are now a part of the history of plastic surgery but in their time some very elegant results for mutilating injuries particularly during the wars became possible through these flaps. As happens frequently in the world of science, ideas occur to scientific workers at about the same time and the idea of a tube pedicle in fact has two fathers – Gillies in England and Filatov in Russia.
10. All this was part of what was collectively called a ‘delay’ (phenomenon) in order to improve the vascularity of the flap which was beyond the one-to-one ratio. The basic delay procedure involved cutting a flap on three sides with its base intact but which was not lifted off its bed which also supplied it with blood. Later in a matter of couple of weeks the flap was lifted from its bed, leaving the base intact and sutured back to ensure that it survived only by way of blood vessels in its base. If the flap survived it was transferred. If only a small part of the flap died, the necrosed part was trimmed and the rest of the flap was transferred. Journals and books published prior to 1970 are filled with papers dealing with the delay procedure on a variety of animals and in some instances on patients. An additional feature of these papers was a variety of drugs used to improve the vascularity of the flaps (pharmacological intervention). Interestingly there is very little evidence that any pharmacological intervention really improves the flaps length-breadth ratio or can save a dying flap. Flaps die because they are improperly planned or poorly executed and then are not closely observed in the post-operative period for tell-tale signs that point to a remedial measure. Nature is robust and efficient. We need to understand her and she is not kind when her rules are broken.

Phil Sykes from England, the archivist of these short notes adds: 

Stuart H Milton was a surgical research assistant with Tom Patterson in the Oxford Plastic Surgery Unit in the late 1960s. He was awarded the Kay- Kilner Prize by the BAPS in 1967 for his essay on “The Tubed Pedicle Flap”. His seminal work using a pig model between 1969 and 1972 was to debunk the rigid “length-breadth” teaching of flap survival by showing that as long as a vascular pedicle was included in the narrow base of a flap it could be extended for the full length of the territory supplied by that vascular system. Like much good research this simple observation opened up whole new areas. Axial pattern flaps, free flaps, muscle amd myocutaneous flaps followed. Sadly he died in America without the recognition he deserved. Had he lived longer he would have seen the results of his work when the rapid growth of safe reconstructive flap surgery took off in the mid 1970s.

Peripheral Nerves

1. Nerves are the peripheral extensions of the central nervous system allowing it to deal with the outer world. Even in unicellular organisms the nucleus is wired via the cytoplasm through its reticular structures which extend up to the organisms cell membrane. Nerves that emerge from the neuronal tissue in the cranium are called the cranial nerves. Those that are connected to the neurons of the spinal cord are called ‘Peripheral Nerves’. The brachial plexus belongs to the latter system.
2. An axon which is the basic unit of a nerve is in fact a cytoplasmic extension of the neuron. Many axons make a fascicle and several fascicles make a nerve. Some nerves are uni-fascicular (one large fascicle). There are other nerves which carry very few fascicles (oligo-fascicular). Unlike in an electrical or fibre optic cable, fascicles within a nerve are known to change position. For e.g. a fascicle which appears at a nine o clock position on a cross section of a nerve at the elbow may have changed its position to six o clock or three o clock when the nerve crosses the wrist. These changes are not entirely random and have been charted to a great extent. Unlike in a non living electrical or fibre optic cable system, fascicles change course entering adjacent bundles forming a grid which helps preserve function in a partial injury to the nerve. The axon is wrapped in connective tissue called endoneurium. The corresponding layer for the fascicle is the perineurium and the nerve itself is enveloped by the epineurium which sends septa separating the fascicle. This connective tissue is elastic and is thicker where nerves cross joints to allow movement.
3. The neuron has a shorter cytoplasmic extension called the dendrite which connects it to other neurons but it is also in contact with axons as well as the parent neuron through synapses. A neuron is remarkably different from the other cells in the body in that it has several outcrops called ‘boutons’ which form the eyes and the ears of the neurons and are connected to these synapses.
4. Peripheral nerves at their spinal end are called roots. The ventral roots are those which arise from the ventral and lateral neuronal tissue of the spinal cord and are motor in nature including a vasomotor component. The dorsal roots receive the sensory nerves but are different from the motor efferents in that they have a spinal ganglion outside the bony spinal structure which contain additional modified neurons (also called inter-neurons) with their own dendrites which connect these neurons to each other. A mixed nerve is called as such when both motor and sensory nerve channels travel together.
5. A bulk of the axons are insulated by a sheath of myelin (myelineated axons) which is made up of proteophospholipids arranged in multiple spiral layers which are derived from the Schwann cells which are like sub stations of the parent neuron and these two cellular structures namely the Schwann cell and the neuron, communicate through the axon. This arrangement therefore is uniquely integrated and far more alive than other linear structures in the body.
6. The insulation of myelin ensures that there is no wastage of the signal conduction that the axons carry and even smaller nerves can be more efficient.
7. A myelineated axon is divided into segments at the ends of which myelin is absent. This area is named after Ranvier. A single Schwann cell envelopes the axon between the two nodes of Ranvier.
8. While conduction of an impulse in an axon occurs by linear molecular movement called slow conduction, conduction also occurs in spikes or leaps (saltatory). The generation of electrical currents is a function (like elsewhere in the body) of the change in the permeability of the cell membrane which is normally ‘gated’ with sodium ions in the extracellular space and the potassium ions within. When sodium ions enter the cell and the potassium exits the cell, depolarization is said to occur. When an electrical discharge is complete, sodium ions get pumped out and potassium flows in passively. The nodes of Ranvier are the sites where these spiked potentials are generated for communication to either side. The node has a higher density of mitochondria which supply the energy for both polarization as well as depolarization.
9. All nerve fibres are not myelineated (though the bulk are). The unmyelineated fibres are enveloped in their entirety by a chain of Schwann cells, their walls abutting each other closely by apposition. Conduction along unmyelineated fibres consequently is less efficient and is proportionate to their cross sectional diameter.
10. Because peripheral nerves are integral to survival from any adverse environmental change, they are high-metabolic structures. The metabolism is entirely aerobic and therefore their blood supply is functionally critical. The extrinsic supply to a nerve comes from branches of major arteries in the vicinity and also from branches of muscular or periosteal vessels. Then they run along and within the epineurium, send proximal and distal branches and therefore help to form a plexus. This plexus then forms the intrinsic system with numerous anastomosis between arterioles and venules and the flow within this arrangement is not unidirectional. The segmental nature of the blood supply of a nerve is such and the sub-epineurial plexus formation is so widespread that trauma to the extrinsic blood supply over some length does not devascularise the nerve as long as the axial epineural and sub-epineurial plexus is not damaged. However, prolonged traction causing elongation between 8-15% will halt the blood supply leading to damage to conduction. From this it also flows that the intrinsic plexus around the fascicles can sustain them even if they are dissected for some length away from the epineurial vessels and they remain as viable units. The endoneurial capillaries are comparatively broader as compared to the other capillaries but are somewhat segregated from the epineurial plexus and contain large volumes of blood as a reservoir confirming the high metabolic nature of this tissue.
11. As is expected, the glabrous or non-hair bearing skin of the sole or the palm has the highest number of sensory receptors as well as free nerve endings in the body. This skin also has a thick epidermal cover which dips into valleys and therefore also has corresponding ridges. The dermis is insinuated into this arrangement and is called the papillary layer of the dermis.
12. The nerves of the skin are both myelineated and un-myelineated and form a subdermal, deep dermal and papillary (at the junction of dermis and epidermis) plexuses from which various nerves proceed to receptor organs for carrying the afferent impulses. In the non glabrous skin free nerve endings also supply the hair follicles and these might be unmyelineated.
13. Of the receptors, Meisners’ corpuscles occupy the dermal papillae and the deepest layers of the epidermal projection and perceive flutter, vibrations and moving touch. The Merkell cell-neurite complex at the epidermo-dermal junction feels constant touch and pressure. The Ruffini’s corpuscle, located throughout the dermis, specializes in detection of position and velocity and the Pacinian corpuscle located sub-dermally is mainly a pressure receptor. Awareness of one’s skin without any stimulation becomes possible because of the basal resting electrical potential within these receptors.
14. Hair and hair follicles are innervated both by myelineated and unmyelineated fibres which convey sensations because of the fine disturbance that the movement of hair causes in the follicle as well as a coarser movement of the hair follicle itself when the skin is deformed.
15. Free nerve endings of both types are present in large numbers throughout all layers of the skin and mainly convey cold and warmth as well as pain, fine tickling sensation as well as that of itching.
16. Afferent impulses arise in the receptor area due to mechanical or ionic changes caused by e.g. heat causing a shift in the balance of cell membrane potentials.
17. While this general anatomical arrangement continues to be replicated in the mucocutaneous junctions as well as the exposed parts of the mucosa, the genital mucocutaneous junctions and their periphery exhibit a very high incidence of free nerve endings as well as a special end organ called Krause’s bulb which is similar to but a slight variant of the Meisner’s corpuscle.
18. The sensory innervations also extend to muscles, tendons, joint capsules, ligaments and the periosteum and they perceive deep sensibility, the sense of position, stretch and tension. In the muscles the receptors are spindle shaped and convey these sensations via heavily myelineated fibres and are connected to receptors in the tendons which are called Golgi bodies and are similar to the Roufini receptors of the skin. Other receptors very similar to the ones in the skin (Pacinian corpuscles) are in abundance in joints, capsules, synovial sheaths, interosseus membranes and are sensitive to acceleration and vibration. In addition free nerve endings which carry the feeling of pain are present in the synovium and joint capsules. The spindle shaped receptors of the muscles are modulated via a centrifugal efferent nerve connection with its external or extra fusal member which then gauges the length, tension and stretch within the muscle fibres, the two together being responsible for coordination and the ultimate contraction of the muscle.
19. The motor end organs or the end plates in the muscle are innervated by a myelineated nerve fibre which breaks into several unmyelineated axons which then lie in a trough along the muscle fibre and are covered by Schwann cells at what is known as a synapse. This area is filled with mitochondria which help supply the energy to change the electrical potential around the axonic cell membrane, resulting in a stimulus to the muscle which contracts because acetylcholine is released from vesicles located around the motor end plate. To summarise, the contraction of a muscle occurs through a stimulus by motor nerve endings, in turn directed by the spinal neurons and the brain and is determined by the position, stretch and tension within the muscle as communicated between the extra fusal and intra fusal muscle end plates which also have a sensory inter communication in between them.
20. Diseases of the nerves are not the province of a surgeon (plastic) but disruptions of nerves by other causes principally injuries or compressions are treated by surgical specialists including plastic surgeons. Leprosy and diabetic neuropathies with consequent effects however are two exceptions where plastic and other surgeons have principally contributed through decompression of nerves as well as reconstruction of nerves and the deformities that these diseases might cause.
21. An injury to a nerve can either be in the form of a temporary functional block in a short segment (neuropraxia) which recovers rapidly (within weeks) or involves anatomical disruption of axons which remain in continuity without disturbing their connecting tissue envelope (axontmesis). In the next category the axonal continuity is severed together with its envelope and recovery is impossible unless co-option of the severed ends is achieved. This is the severest form of injury and is called neurotmesis. This classification of Seddon has been enlarged by Sunderland to take into account the fascicular nature of nerves and their severance. It is to be noted that many nerve injuries are likely to be a mixture of all three types where adjacent areas of neuropraxia and axontmesis might be present when the nerve is severed.
22. When nerves are injured the distal axons degenerate and the end organ (sensory or motor) undergoes changes in which its supportive structures atrophy depending on their lifecycle, ultimately leading to complete degeneration of the end organ itself. From here on reinnervation becomes impossible. However if axonal regeneration occurs before the end organ becomes extinct, reinnervation is possible in varying degrees as the supporting tissue gets relaid. Pending reconstruction of a nerve, a deinnervated muscle can be subjected to intermittent electrical stimulation in order to maintain its membrane potential.
23. When an axon is severed, the distal axon disintegrates together with its myelin sheath reaching up to the end plate. Proximally the fragmentation halts at the next node of Ranvier. The corresponding neuron perceives this change and alters its strategy and downgrades the function of conduction of impulses and upgrades its regenerative function. Synaptic transmissions reduce and the boutons withdraw within the neuron. The riboxynucleic acid content rises, protein synthesis takes precedence over conduction activities and the level of substances needed for transmission falls.
24. Within as early as 24 hours the severed proximal end of the axon forms a bulging growth cone which advances together with axonic growth collaterals from not only the immediately proximal node but also from up to several segments before it and reaches the zone of injury. This development is a throwback to when axons were progressing towards their destination during embryonic development. When an axon establishes contact with its distal injured counterpart and succeeds in entering the distal axonal tube, it’s collaterals withdraw or degenerate. As the axon enters the distal endoneurial sheath, Schwann cells are seen growing around the axon in the proximal to distal direction. Myelineation is replicated if the original axon had the advantage of myelin cover. The biological by products of these reconstructive efforts are transported back to the neuron through the peri-axonal space.
25. What prevents the axon from entering the distal intra-neurial space, is a scar or the ever present post-injury extracellular matrix. Axonic collaterals are advantageous in this situation allowing a multiple choice for penetration. Though not conclusively proved, some evidence has emerged that the growth cone might have enzymatic products which help the axons to burrow through the scar or the extra cellular matrix.
26. What is crucial to this axonal advancement is the patency of endo-neurial space in the distal part of the injured nerve. Schwann cells start clearing the area of myelin sheath and form longitudinal rows to maintain this endo-neurial space but their very survival is dependent on the original axonal continuity. If axons do not penetrate this new space, collagen, the ever ready ‘filler’, slowly occupies this space as a part of general repair and nerve regeneration fails partly or completely.
27. Even when axonic penetration is successful, the endo neurial space is usually not of the same diameter and therefore the axonic diameter has to reduce and the inter nodal distance in the newly penetrated axon is also reduced. The rate of axonal growth depends on the distance between the site of injury and the corresponding neuronal cell. The longer the distance, the slower the growth. Injuries in the upper arm will heal faster as compared to those at the wrist if the conditions and the nature of injury are identical. On the other hand a proximal injury means that the axonal damage occurs in fascicles, which are not yet end organ specific, and because post injury axonal penetration must remain a random event, restoration of end organ function might be that much poorer. A nerve in the palm or foot in comparison is more ‘end organ’ specific with fewer axons and therefore, though axonal penetration might begin later (by the above law), the end result might be more satisfactory notwithstanding some randomness of axonal penetration.
28. In the severe forms of nerve injuries, the degree of retraction of axons is a function of the integrity of the epineurial tissue which disallows too much withdrawal by virtue of constraints of space as well as the septa that run across from the epineurium. The spontaneous natural repair in such circumstances is possible but will remain quite unsatisfactory even though the axons will penetrate the natural scar in the zone of injury resulting in an entity called neuroma in continuity which is a jumble of axonal sprouts entangled in a scar some of which might have entered the distal axonal tubes.
29. In the severest forms with extensive laceration, spontaneous regenerative reinnervation invariably fails particularly when the severed nerve ends lie at some distance from each-other.
30. Some points are noted below:
a. The greatest impediment to repair of nerves is a scar that will obstruct axonal penetration.
b. The random nature of axonal penetration even when meticulous surgical coaption is achieved will adversely affect the end result. This is particularly true of a mixed nerve though it must be noted that what we call a pure motor nerve is in a way a mixed nerve because it carries proprioceptive and autonomic sensory components.
c. Early repair is crucial so that the distal deinnervated systems together with the end organ do not lapse in to a state of irretrievable state of atrophy and loss of function.
d. Yet adequate treatment of associated injuries, particularly vascular injuries and fixation of unstable fractures, must be carried out prior to or together with repair of nerves.
e. A good vascular uncontaminated bed helps regeneration of nerves. The results of repair of nerves are best in the younger patients and the results slowly deteriorate with age. Unlike in tendons, repair of nerves can be undertaken even if the flap cover is being done in two stages, in the first stage itself as long as the wound is reasonably well closed.
f. A proximal injury nearer the neuron has a greater destructive influence on the neuron and consequently its reparative process suffers.
g. Axon avulsion from the cell membrane of a neuron is almost fatal to a neuron and therefore repairs are impossible and the surgeon might have to opt for muscle and tendon transfers to restore function. Post-ganglionic disruptions fare far better in this regard.
h. Notwithstanding what has been narrated, the results of repair for injuries to nerves which supply major muscles for e.g. shoulder girdle, though they are nearer the neuron, may have a gratifying result because their movements are coarse and are judged as such. On the other hand repair to nerves to distal smaller muscles, e.g. the lumbricals and the interrossi in the hand, will show that, though the co-option of the severed nerves have a lesser chance of displaced axonal penetration, the results might appear unsatisfactory If looked at critically because the functions of these muscles are more intricate and finely calibrated. However these procedures continue to be very gratifying vis a vis clinical results.
31. Reinnervation of a muscle when it occurs gives the best results when the deinnervated muscle is nursed in a satisfactory state by electrical stimulation and physical therapy, because an atrophied muscle not only becomes smaller in size but is progressively replaced by connective tissue and, by two years, few muscle fibres are recognizable. Even after the motor end plate is reinnervated a lag period is noticed of about two or three weeks before direct stimulation of the nerve produces an adequate muscular contraction. It has been mentioned earlier in this chapter that two parallel intra fusal and extra fusal spindle shaped motor end plates coordinate with each other through their additional inter connected sensory function in gauging the length, strength and position of muscle fibres, the intrafusal end plate sending afferent fibres to the extra fusal end plate. Even in ideal conditions neurotisation may be not be able to restore this connection fully, resulting in a not so perfect return of function.
32. In the skin the Merkel cell neurite degenerates the fastest while the Pacinian corpuscle survives for the longest period. The Miesners’ corpuscle occupies the middle position in this regard. The return of sensory function is dependent on the surviving sensory end organs as well as axonal sprouting and regeneration. Most of the studies in this regard have been done on skin grafts and there is evidence that there might be some specificity when it comes to reinnervation when glabrous and hairy skin are interchanged in an experiment where the bed from which axons will sprout remains the same. A bed that originally supplied sensory modalities of hairy skin does better when hairy skin is transplanted on the bed and vice versa. In any event the varying rate of degeneration of the different receptors and the problems of random penetration by axons usually means that a return to almost normal sensibility is rare when this sensibility is tested with high precision. An additional problem in monkeys and man is the functional rigidity of the cortical sensory zones. If the peripheral reinnervation is not exact the cerebral reception is confused and an accurate perception becomes difficult. The cortical areas in the lower animals are more flexible in this regard and the return of sensation in them is far better even if the reinnervation is crossed.
33. Because a nerve transmits its impulses by way of an electrical discharge caused by a series of depolarizing/repolarising events, its functioning can be best studied by electro diagnostic tools.
34. This is done in two ways
a. By sending a current along the length of a nerve and studying its speed and / or locating at which place this current gets impeded or stops completely in its progress. This is called the study of nerve conduction velocity.
b. By studying the effects of this current directly on an end organ like a muscle which is called electromyography.
35. Nerve conduction velocity is measured by putting two electrodes at some distance on a nerve, one of which will be near the end organ and the other further away. What gets tested is the segment between the two electrodes. One of the best applications of this method is to be able to diagnose a compression neuropathy (for e.g. Carpal tunnel syndrome). Nerve conduction velocity can also diagnose multiple areas of compression by moving the electrodes along the length of the nerve. This method is best applied to larger nerve trunks with larger faster axons and is unsuitable for small fibre neuropathies.
36. Electromyography employs small needles which penetrate a muscle and test its electrical potential. In a normal resting state, the muscle will not exhibit any electrical activity. Deinnervation of the muscle causes an abnormal secretion of acetylcholine leading to small contractions of muscle fibres or fibrillation which these needles will record. The time lag for the fibrillation to appear is a function of the location of the nerve injury. The nearer the injury, the earlier the fibrillation. If the injury is distant, distal axonal degeneration takes that much longer and fibrillation will start occurring several days or weeks from the time of injury. The presence of fibrillations is diagnostic of deinnervated but living muscle and indicates that reinnervation can be undertaken and might succeed. After reinnervation its success at the motor end plate can be gauged by the response of the muscle on stimulating the nerve proximal to the site of repair (or decompression) by the appearance of polyphasic potentials or waves.
37. After what was a depressing era in which the results of repairs of nerves showed very little benefit, in the last fifty years with better understanding of the physiology of how nerves respond to injuries and their fascicular arrangement, repair of nerves is viewed with far less gloom than before. The advent of the operating microscope has played a major role in this transformation.
38. Because the results of surgical coaption have been indifferent in the past and also because these failures were attributed to the scarring that surgical apposition invariably caused, the technique of placing the two cut ends of the nerve, after pre-operative preparation, close to each other in a living conduit (eg. a vein or an artery) or a non- living tube, for example rubber or tantalum, has been tried over several decades but has not shown to be any better than a standard surgical coaption.
39. In fact there is little unanimity amongst surgeons even about the superiority of fascicular repair (perineurial) over an epineurial repair. With the arrival of a biological glue by which properly aligned ends of nerves are apposed to each other and then treated and fixed with this adhesive, a new era might be being unveiled in this respect. The alignment of the nerve with the corresponding fascicles properly facing each other is crucial whatever the form of repair. In this respect in the larger nerves the axial epineurial vessel which runs on the body of the nerve is greatly helpful to align the nerve properly. The exact topography of fascicles in individual nerves as well as their stimulation to ascertain their effect on distal end organs or to elicit sensory feelings is beyond the scope of this text.
40. Whatever method is employed to coapt nerves the aim of the surgeon is to fashion nerve ends which are free of scar. Having removed the scar, the nerve ends must appear to be alive (altogether a difficult thing to gauge precisely) from which fascicles must not be hanging too far out from the epineurial edge. The elimination of scar or debris or dead crushed fascicles or a neuroma begins at some distance from the injury by a longitudinal incision along the length of the nerve in the epineurium. The epineurium having being incised, some fine dissection can enter a deeper intra-fascicular plain. This then is carried towards the severed ends. By training, observation, a tactile impression of how the tissue cuts and with the help of magnification it is possible to identify the last living post (!) of the nerve at both ends. This recognition however remains mainly empirical and has a learning curve. The freshening of nerve ends is left to the very end when all scar and non viable tissue is sectioned off and repair must begin quickly. The other commonly used method is to take transverse cuts across the nerve beginning from the injured end till normal scarless fascicular bundles are seen.

Top left. Healed wound front of forearm. Fingers show classical median nerve deficit. Top middle: Median nerve shows neuroma in continuity. Top right: the neuroma has been excised. Middle left: drawing to show freshened edges without any scar. Middle centre and middle right: repair in progress and completed. Below left: Transverse method of cutting the nerve till scarless fascicles are seen. Below middle: Fascicles are protruding but not hanging. Orientation has been aligned with the artery running along the nerve. Bottom right: The end of the nerve prior to repair. Photographs courtesy: Mukund Thatte, Mumbai

41. When repair is finally undertaken, the sutures must hold easily (no tension) and the nerve must itself lie comfortably on an unscarred vascularised bed (without being taut or getting blanched even when the part is put through its normal motion). The apposition (fascicular or epineural) must not be such that repaired neural tissue tends to buckle and appears to be too far prolapsed from its epineurial sheath prior to suturing.
42. If there is tension when the ends of the nerve are apposed (this can be gauged when the nerve is being prepared for suturing) some trimming of mesoneurium can be undertaken on either side to gain slack. The choice of the caliber of the suture material is 100 for fascicular repair and 80 for epineurial repair. In order to achieve non-traumatic repair of fascicles “tension freeing sutures” of up to 70 or 80 can be temporarily placed on the epineurial tissue. These effect easy apposition of the fascicles and they then can be replaced with final sutures. Though the new biological glue now appears poised to replace elaborate and labourious suturing.
43. Tension, infection and foreign body interference near the axons will invariably mar the end result.
44. Notwithstanding the controversies about when an injured nerve should be repaired, two practices are now universally accepted.
a. An iatrogenic injury to the nerve at the time of a planned surgical procedure (e.g. the trunk or the branch of a median nerve while releasing a carpal tunnel compression) or an otherwise clean transection of a nerve or nerves with or without injury to tendons should be repaired primarily within several hours.
b. In the other extreme category for e.g. an indiscriminate war wound involving penetration and / or a blast effect with other injuries such as fractures in the same zone further complicated by contamination and the need to treat other parts of the body to stabilize the patient, a delay becomes inevitable because,
i. The patient needs to be stabilized, the fractures need to be fixed and vascular restoration might need to be undertaken
ii. The nature of the nerve injury might be of a complex nature over a length including axontmesis and neurotmesis, patches of devascularisation or as in a bullet wound, a friction or a thermal burn.
45. The exact nature and extent of such an injury becomes apparent several weeks later both clinically as well as by electrophysiological methods. The waiting period in such cases cannot of course be extended to four or six months. The old thinking that old injuries can be repaired even after a year or several years is not accepted any more. Injuries to nerves under the above circumstances might involve excision of dead nerve tissue over several centimeters, will require careful mobilization before coaption can be achieved without tension. These are the kind of cases that might need to be treated with nerve grafts.
46. Nerve grafting becomes necessary when coaption is not possible. The commonest nerve harvested is the sural nerve though for small gaps in digital nerves the terminal portion of posterior interosseous nerve is useful. The medial cutaneous nerve of the arm is another choice. The preparation proceeds in the same manner as for coaption. The repair is however staggered in that the fascicles are cut at different levels both in the proximal and distal ends to avoid a common scar. The nerve graft is not used as a single strand but is dissected into fascicles which are joined individually and the end result does not appear like a single nerve unit but an array of strands spread across some millimeters. The requirements for coaption and nerve grafts vis a vis the nature of bed including its vascularity as well as the post-operative care are not different. A 100 suture is most suitable for this purpose and the problem of tension does not arise if adequate donor nerve is harvested.

Top left: Significant segment of median nerve showing ischaemic effect and scar due to a Volkman's effect. Top right: Ischaemic segment excised. Below left: Sural nerve cable grafts employed to do a fascicular repair. Below right: After the repair is complete. Photographs courtesy: Mukund Thatte, Mumbai

Ischaemic effects can also be produced by constricting pressure. On the left, Trophic changes in the tip of the index and the thumb in carpal tunnel syndrome. Right: In a less frequent clinical condition the ulnar nerve shows oedema localised proxmial to the cubital tunnel which needs to be released and in this instance because the lesion is early, the oedema will subside and will lead to full recovery. Photographs courtesy: Mukund Thatte, Mumbai

 

47. Vascularised nerve grafts have been tried recently especially for large proximal severed nerve trunks surrounded by poor vascular beds and there is experimental evidence to suggest that the rate of reinnervation is better than ordinary grafts. The sural, superficial radial or the saphenous nerves have been used for this purpose. Pedicled vascularised nerve grafts have also been tried. The vascular supply of these grafts runs along the epineurial vessel and grafts are chosen when a single dominant vessel supplies the nerve (e.g. the ulnar nerve from the middle of the arm to the wrist is supplied by a single dominant vessel and can be harvested in this entire length). Post operative care of these procedures needs to be even more exacting and has to be very gentle and precise because of the size of the micro anastomosis.
48. Though surgery on nerves might not be a major component of an average plastic surgeons workload, this chapter has been written at some length because it reveals fascinating details of how elegant and efficient nature is vis a vis the structure, function and attempts at repair that the body undertakes when it comes to nerves.
Dr. Visweswar Bhattacharya from Varanasi adds as an adjunct to point 23 as follows:
In the event of a nerve injury, the axons proximal to the injury relay information to the corresponding neurons. The cell body is located within the spinal cord (motor nerve cell) or posterior root ganglion (sensory nerve cell). They swell in size, reflecting a greater enzymatic activity, increase in the overall content of the amino acids, transformation of the RNA to a more active state and a rise in the quantity of nucleic acid. Proteins formed as a consequence of this activity are transported to the site of the nerve injury to help in the process of repair. Such a neuronal regenerative contribution is dependent upon the distance between the site of the injury and the neurons. In an injury at the wrist to the ulnar or the medial nerve, the reparative neuronal activity for example will continue for 60-90 days.

Repair of Tendons

1. A tendon is a strong, somewhat elastic, modified connective tissue which arises from a muscle and attaches to a bone by way of a fibrous or fibrocartilaginous tissue. When the muscle contracts, the tendon pulls on the bone causing a movement in a joint proximal to its attachment.
2. The tendon has a layer of epitenon on the outside which encloses multiple fasciculi composed of fibres, each fibre is made up of cross-linked fibrils which is in turn made up of collagen. The cross linking provides the tendons with their tensile strength. The tendon also has its blood vessels, nerves and lymphatics. Its internal lubrication is provided by a ground substance composed of large molecular carbohydrates combined with amino acids (glycosamine glycans).
3. Because a tendon must glide smoothly and also not bow string, it is covered with a variety of layers; the smooth epitenon, loose areolar tissue called paratenon which contains mucopolysaccharides to allow smooth gliding and it also passes through a variety of tunnels called tendon sheaths. These sheaths or tunnels prevent bow stringing. They are not continuous but are interrupted and occasionally give an appearance of rings which are called pulleys. The flexion of fingers which may begin at the distal phalanx can therefore be smoothly completed via all the proximal joints to make a fist without bow stringing.
4. In the hand, two bursae, each for the long flexor of the thumb and the flexors of the little finger, a palmar bursa for the flexors of the central three fingers and separate bursae beyond this central bursa for the long flexors of the central fingers along their length are an additional lubricating environment. The reasons for this peculiar arrangement lie buried in the evolutionary process.
5. The epitenon is a cellular structure and its invagination between the fascicles is named endotenon (also cellular). In addition, the tendon has distinct cells called tenocytes. The exact function of each of these cells is not known. The tendon also has a mesotenon which is a condensation of the soft tissue of the paratenon and carries blood vessels. Similar blood vessels also supply the tendon via viniculii located in cruciate structures near the pulleys. The tendon is also usually supplied by arterioles near its origin from the muscle and this supply can be called intrinsic. The tendon therefore has a dual blood supply. The tendon does not get any blood supply from its distal, bony attachment. The tendon is enveloped by the paratenon or the bursae by a process of invagination (as in the abdomen or thorax, parietal or visceral peritoneum or pleura) and the space created by invagination is filled with a fluid which has a role to play in both nourishing the tendons and in its gliding. Tendons which glide very near the bone and/or skin are also protected by bursae (e.g. the pre-patellar or the supra patellar bursa). The nerve supply to the tendon is almost completely afferent, relaying its impulses through muscular or peripheral nerves.
6. When a tendon snaps as in a closed injury, or is cut and retracts because of both its elasticity and the proximal muscular pull, up to a point allowed by its anatomy, it must suffer a loss of some or almost all of its extrinsic blood supply. Yet tendons heal when repaired (probably by virtue of their intrinsic supply). But grafts of tendons used as a bridge also heal at the repaired ends with a tensile function approaching that of a normal tendon system. These facts suggest that the tendon, with a very low rate of metabolism, survives with a diminished or an almost non-existent blood supply, and can heal when joined, either through its own cells or by way of a repair process which starts in its external environment.
7. If a tendon is sutured, after it has been divided as a part of an open wound, its repair at least partly, will be through an extrinsic process. As it is when the ends of a cut tendon are joined, a scar will form during the process of repair within its fascicles as well as its surroundings leading to adhesions and loss of gliding function which is not uncommon when tendons are repaired. Yet this surprisingly does not occur in all cases leading to two possible deductions.
a. That the external reparative process withdraws once the repair is achieved or
b. The tendons repair intrinsically on their own when joined, notwithstanding their reduced blood supply, by virtue of nourishment from the fluid surrounding them without taking recourse to the use of extracellular matrix deposited around them (for ECM or extracellular matrix, see previous chapter on wound healing).
8. This matter is not settled, certainly not through verifiable human trials but the weight of evidence may now be veering to the view that the intrinsic repair of tendons is very valuable to the final outcome and is indeed possible without any external contribution as confirmed by experiments on animals.
9. That a long flexor of a finger avulsed from its bony attachment or a mallet finger caused by avulsion of its osseous attachment of the extensor have by far the best results when their bony attachments are firmly secured is a common experience. The bone in these cases unites with vigour and the tendon in fact has not been repaired at all.
10. What flows from the above is the need to repair tendons in a manner which will approximate the epitenon of the cut tendons most meticulously to avoid as much as possible if not eliminate all together the extrinsic reparative process. Unfortunately the other ‘tension overcoming’ sutures, made of whatever substance used in repair of tendons, go through the epitenon at more than one point and also leave knots on the outer surface of the tendon, inviting a natural but a possibly complicating reaction from the surrounding tissue. This situation can improve only if a glue like substance is discovered which will hold the tendon together while overcoming its natural pull and must also not provoke any reaction in the surrounding tissue.
11. The technique or method of repairing a tendon has seen many variations over the last fifty years without significantly improving the outcomes of these repairs. What has changed the results dramatically towards the better is a paradigm shift towards a primary repair both for closed ruptures and open lacerations at all levels. This has been necessitated because of the earlier experience that to avoid primary repairs is to invite a collapse of the sheaths and the tunnels. Any reconstruction of these sheaths and tunnels invited more scars. This has particular reference to the hand because unlike in other parts of the body, particularly the foot, the movements in the hand need to be far more dexterous.
12. In the event, the division of the hand into zones to indicate if primary or secondary repairs should be undertaken has somewhat lapsed. There is no denying though that the area lying over the two proximal phalanges of the fingers presents difficulties. The sheath and the pulleys, the attachment of the split sublimis over the middle phalanx and the profundus traversing through this bifurcation is a crowded situation and any healing in this area with any extrinsic scar could be a recipe for poor results. On the other hand as mentioned earlier, a delayed repair invariably leads to a collapse of the system of tunnels and their sheaths which are crucial to the gliding motion of the tendon and also to prevent bow stringing. Because retunnelling the sheaths was invariably found to be difficult and any neo-reconstruction of the collapsed tunnels lead to adhesions, a meticulous primary repair of the profundus tendons has in the long run proved to be a much better option when both the profundus and the sublimis have been cut. In this scenario, the attachment of the sublimis to the bone is not removed but the rest of the tendon is excised to allow more space and play for the profundus tendon in the proximal part of the sheath. It helps to reduce scarring in this area by keeping the exposure in the finger to the minimum and to find the tunnels blindly by way of a probe or a rigid catheter and then thread the retracted tendon rather than doing a wide exposure. An ultrasound examination, particularly of the palm, can be very valuable to locate the proximal retracted end of the lacerated tendon and minimize the palmar exposure. In the primary repair, it is easier to get the tendons to their place of repair which might become very difficult after several weeks by which time they may get quite rigid, another reason for undertaking a primary repair.
13. In order that adhesions are minimized the total length of the tunnelled area can be judiciously reduced after ensuring that some gliding zones are kept intact and it is confirmed on the table that bow stringing is not occurring.

Flexor tendon repair technique: A) The tendon ends are retrieved through the pulleys and retained for suturing by transfixing with a hypodermic needle. To make it easy, the posterior epitendinous sutures are put in first using 6.0 polypropylene. For performing the core suture 3.0 polypropylene suture is used and the first pass is taken. It must emerge about a cm from the cut end. B and C) The transverse pass is done next. It must be done a little proximally so that the loop grasps some amount of tendon material. D and E) The longitudinal pass is then done and it must again help to grasp some tendon tissue and emerge through the cut end of the tendon. F and G) The same process is carried out in the other end of the cut tendon and the knot is tried. It is just done tight enough to bring the two ends together and avoid bunching of the tissue. H) The anterior continuous epitendinous sutures are now put and the repair is complete. Photographs courtesy: Raja Sabhapati, Ganga Hospital, Coimbatore

Primary Flexor Tendon Repair – Zone 2 A) The ends are identified and gently kneaded through the pulleys. B) The ends are retained by a transfixing needle through the proximal segment and repair is done between the A 4 and A 5 pulleys. C) After repair to facilitate free movement the A 4 pulley is partially vented. D & E) The result after 6 months. Photographs courtesy Raja Sabhapati, Ganga Hospital, Coimbatore

14. The results of primary repair of tendons are very good when the wounds are clean, sharp and small.
15. When the injury includes fractures, they must be rigidly stabilized so that primary healing of bones occurs and minimizes scars.
16. In larger contaminated wounds with avulsed and / or contused skin, which requires replacement with a flap, where the tendon sheaths are intact, yet the tendons are cut and have retracted, a tendon repair with a flap cover might be attempted if post operatively the hand can be maintained in a position necessary to take away the tension from the repaired ends of a tendon. This might be possible with a free flap or a distally based radial artery flap but is almost impossible with a distant two stage flap except perhaps when a cross finger flap will suffice. This particularly pertains to repairs of flexor tendons in the hand.

When the skin over the injured tendons is poor (left), a one stage flap, in this instance, a posterior-inter osseous flap can be used (right) and the tendons can be repaired at the same time, extensor policis and the small abductor of the thumb (centre). The patient also had fractures underneath which have been primarily fixed. Photographs courtesy: Vinita Puri, KEM Hospital Mumbai.

17. When amputated digits or the hand at the level of the wrist or below are reimplantable because the nature of the injury is sharp, tendon repairs are best done together with repair of nerves and vessels as well as rigid fixation of fractures.
18. When wounds are in the nature of avulsion crush injuries, and are contaminated, involve multiple planes and are ragged, whether they are accompanied by fractures or not, it is best to achieve flap cover and postpone reconstruction of tendons till after healing is complete.
19. When tendons are repaired secondarily, ideally a retracted tendon is located, pulled through the tunnels and sutured to its distal cut end.
20. When a retracted tendon has shrunk and cannot be pulled through, a tendon graft becomes necessary.

Technique of Flexor Tendon Grafting A) A long standing Zone 2 flexor tendon injury of the ring finger, B) explored by mid lateral incision and extended to the palm. C) The proximal end identified in the palm and Palmaris longus tendon graft harvested. D) Distal attachment done to the FDP stump, skin incision in the finger closed and tension adjusted. E) Finger cascade at the completion of the operation. Photographs courtesy Raja Sabhapati, Ganga Hospital, Coimbatore

Technique of Flexor Tendon Grafting A) Long standing zone 2 flexor tendon injury of the little finger, with markings for exploration. B) When good stump is not available in the palm, the proximal attachment is done in the distal forearm with Palmaris longus tendon graft and tension adjusted. C) Restoration of the finger cascade at the completion of the operation. Photographs courtesy Raja Sabhapati, Ganga Hospital, Coimbatore

When wounds are more complicated (as in para 16 ) silastic rods are the best option.

21. Whether such rods can be placed at the time that flap cover is achieved will remain a matter of judgment and choice. A silastic rod achieves two important things. It creates a tunnel around it and its placement means that a tendon graft can be threaded through the tunnel with minimum exposure, temporarily attached to the rod as it is withdrawn. In effect, it entails two small exposures at the proximal and distal sites of repair.
22. A tendon graft is devascularised tissue and the nature of its survival is a matter of debate. While a necrosis of this graft (at its ends or along its length) is uncommon and it certainly has a fairly high survival rate with or without adhesions. Its unpredictable survival also means that its final functional length might shorten, allowing only restricted movement across joints across which it had been placed, and will produce a tenodesing effect. The functional nature and extent of this contracture in each individual case needs to be determined when one is considering whether re-exploration can be undertaken to reduce adhesions if any, or placing a new graft or a silastic rod.
23. In the surgery of tendon transfers, if the transferred tendon is not lying adjacent to the tendon to which it is transferred, and it requires extensive mobilisation (for e.g. extensor to a flexor or vice-versa), the transferred tendon is relatively devascularised and this might affect the results.
24. When adhesolysis in the hand needs to be undertaken it will need patience, must be done through properly planned incisions, preferably aided by magnification to avoid injury to nerves or vessels.
25. Incisions in the hand should as far as possible not violate natural creases in the wrist or the palm. In the fingers a mid neutral incision along the radial or ulnar side or a zig zag incision over the palmar surface of fingers give adequate exposure and result in good scars without any resultant contracture.
26. One of the changes that has accompanied primary repair of tendons is in the manner in which the fingers are mobilized post operatively. The idea behind this current method of mobilization is to keep the inter-phalangeal joints mobile without putting any strain on the repaired tendons. The technique involves immobilization of the hand by a dorsal plaster slab or a splint with the wrist at about 20° flexion and the meta carpo phalangeal joints at 90° flexion but the IP joints are kept free. The patient is advised to press on the fingers, effect passive flexion and then allow the fingers to extend by voluntary effort. This manoeuvre avoids stiffness of IP joints and also allows some tension free movement of the repaired tendons. This position is maintained for 3 weeks followed by active voluntary flexion while keeping the wrist flexed but with the metacarpo-phalyngeal joint free from the splints.
27. The plantaris or the Palmaris longus are two tendons frequently employed as tendon grafts because they are relatively dispensible, can be easily accessed and are of a dimension that can be threaded through the tendon sheaths of the hand. Of the two Palmaris longus, if present, is preferred particularly if it is on the same side on which surgery is done so that two operative fields are avoided. When more than one tendon graft is needed, up to four tendons, two each of the Palmaris and Plantaris can be harvested, though occasionally, a thick plantaris can be split vertically in a precise manner and can be used as two grafts.
28. Post operative adhesions in the hand, particularly after any form of reconstruction of a tendon, remain unpredictable. There is no verifiable animal evidence available to suggest that a pharmacological intervention will prevent formation of adhesions. The same applies to any form of radiation treatment or treatment with ultrasound waves.
29. This chapter as has been the practice in the past focuses more on the hand than other parts of the body because the hand is a vital, multi-dimensional organ as compared to the leg or the foot and also because injuries and repairs of tendons of other parts is also the province of orthopedic surgery. The hand is also prone to more intricate injuries.

Wound Healing and Scars

In nature, life heals itself unless one or several of its systems fail. When the systemic failure is complete and irreversible, death ensues and healing is not possible.
Physiology of Wound Healing
19. The basic concept as to how wounds heal have not really changed over the last quarter century. What has changed exponentially however is the understanding of a variety of factors that control this process. The more important ones are mentioned towards the end of this chapter.
20. Wound healing begins with the formation of a blood clot, which both acts as a seal and is also a rich medium for bacteria to grow, a fact clinicians must bear in mind. Almost simultaneously starts an inflammatory response. The aggregated platelets in the clot stimulate fibroblasts and endothelial cells. Local vascular dilatation follows the inflammatory response. Clot formation also releases substances which increase permeability of vessels and white blood cells, mainly polymorphonuclear, pour out. They scavenge dead tissue and counteract bacteria. Monocytes follow the polymorphonuclear cells in two or three days, modify to become macrophages which continue to phagocytose tissues but also secrete factors stimulating the local endothelial cells, fibroblasts and keratinocytes to start the repair process. In the course of repair, the original fibrin platelet matrix is replaced by what is called ECM (extracellular matrix) which through a succession of initial ingredients ultimately lays down collagen. Initially called a tropocollagen, its molecules then form cross connections to form fibrils and then several fibrils forms a fibre. These fibres together form the fibrous tissue of a scar.
Factors influencing wound healing
21. A living thing can be a host to a variety of other living things and this coexistence is known to be mutually beneficial. But this rule is not universal and some organisms (viruses, bacteria and parasites) can be detrimental, even fatal to another life. These invaders can have local, regional or systemic effects which affect the healing processes as they colonise tissues.
22. A cancer cell is in a way also an alien creature and will grow at the expense of the host and create circumstances which will retard or completely inhibit the healing process.
23. The healing process depends upon the delivery of certain substances and cells to the affected area. The end products of the healing process also need to be cleared from the area.
24. The cells that arrive to heal, the local cells who help healing and the substances that are laid down in the process of healing are all dependent on a normal metabolism and circulation of blood.
25. It flows from the above that any arterial venous or lymphatic insufficiency will influence healing adversely. A disease like diabetes may have a two or three pronged effect via poor micro circulation, a high level of glucose available to the organisms but its poor utilization by host cells and may have had a deleterious effect on protein metabolism. The proteins constitute the basic building blocks throughout life. In modern times, morbid obesity and administration of corticosteroids have been incriminated in delayed healing.
26. The present state of our knowledge of embryology indicates that the nervous system is the master and leader of growth and development. Nothwithstanding the appearance of virtual autonomy of a variety of regions the nervous system is not a silent spectator to the events in these regions. The autonomic nervous system for example is closely linked to the way blood flows in and out of a given area. A curtailment of the nervous system either regional (a localized peripheral neuropathy) or more widespread (a paraplegia or quadriplegia) will harm the vasomotor function, reduce its flexible responses and create anaerobic conditions and retard healing.
27. Immune suppression not only reduces the healing process because the responses to the call for healing are meager but also because infection can occur with greater ease in an immunocompromised individual.
28. The psychological state of the patient may also influence wound healing. Though a variety of diseases have now been unequivocally linked to certain states of mind over a length of time, no substantive, verifiable work on the role of such states on wounds has been published though it stands to reason that the psychological state unlike everywhere else in the body cannot be a mute spectator to the process of healing.
29. Radiation either given as a therapy or received accidentally at work or in war can lead to death of cells and/or a variety of degrees of deprivation in the molecular function of a cell. The most conspicuous results of which are failure to grow and heal. Irradiated areas should therefore need close scrutiny by clinicians.
30. In general a clinician must therefore constantly seek reasons as to why a wound is not healing rather than seek avenues of hastening the natural healing process, which should be self sufficient. For example an ordinary wound on the ankle festering because of lack of rest and colonized by organisms can rapidly heal without any antibiotic or local ointments by way of a simple below knee rigid walking plaster cast which will give adequate rest to the part. All wounds need rest for healing.
Healing by primary and secondary intention, and scars
31. All wounds heal by formation of a scar. The scarring is less when the wound edges are joined together soon after the wounds are created (healing by primary intention). Wounds joined later, several hours after a proper debridement, also fall into the same category. However wounds which need to be secondarily excised after several days of their occurrence and then approximated might behave slightly differently because the process of healing by secondary intention is already begun and this process in the bed of the wound as well as the periphery of the wound means some additional scar formation.
32. When wound edges are not approximated during the process of healing the repair takes place by secondary intention. While the details of this process are described later, one of the more important components of this healing is the ability in the wound to pull the surrounding skin concentrically towards the centre of the wound. This contraction is facilitated if the surrounding skin in loose. For example, the large wounds left behind after excising a perianal fistula by the older method heal rapidly with surprisingly little scarring. Scrotal wounds also show this quality. Wounds along the anterior border of the tibia on the other hand, where there is no such loose skin, are therefore best treated with care lest scars form in this area which are vulnerable even to trivial injury.
33. The statement “all wounds heal with formation of scars” does not apply to foetal healing in early gestation. Here growth and development is occurring at a rapid pace and enough potential is available within the totipotent cells to build anew. The need to replace the lost tissue by scar is therefore not felt. This phase wanes off rather rapidly after the fourth month of gestation by which time the foetus is fully developed and only increases in dimensions over the remaining months. The scarless healing mentioned above is not determined by the environment of the foetus (for example the amniotic fluid) but is inherent in the foetus.
34. During secondary healing the bed of the wound is occupied by this developing collagen within a meshwork of blood vessels. This is called granulation tissue and has been dealt with in chapter 2, namely skin grafting.
35. This granulating bed, if not grafted with skin which carries dermis as well epidermis, can at best epithelialise across some distance and this gives the area only a tenuous cover without any proper established blood supply, which survives by imbibing oxygenated fluid from the bed. This invites repeated breakdowns following trivial insults.
36. Even in primary healing, the scar has only a thin layer of epithelium over it but the scar’s dimensions are small and, unlike the situation in a large area healed by secondary intention, no area is too far away from a properly established blood supply.
37. The dermal component of skin has elastic tissue allowing it a certain flexibility and this elastic tissue is laid in a manner that will allow ease of movement at the joints. In a classical example the direction of elastic tissue at the wrist crease is along or parallel to the crease and not across it. The nasolabial fold is another such example. Any incision along the wrist crease will create a very small defect as opposed to an incision across it. A simple one layer of suturing at the wrist crease and then immobilization for a short period in a neutral position will bring the elastic fibers together when the incision is parallel to it. As opposed to that, a vertical incision across the crease will retract the skin to a greater extent. The elastic recoil of this tissue continues for several weeks putting a retracting force on the healing process and in a way produces a secondary type of healing in the dermal zone creating a broader scar. To avoid this, the dermis needs to be approximated closely by a suture material which will retain its strength for several weeks or months to allow for a proper durable end to end opposition to produce primary healing of the dermis. The cross-hatch marks of the good old days, following interrupted vertical mattress sutures, resulted from dermal injury causing epidermo-dermal necrosis as a result of pressure of the suture material on post operative oedematous skin. This necrosis is also a traumatic wound which, like everything else, heals with a scar. A proper close closure of the dermal component of a wound avoids the need to take broad sutures across all layers of the skin and subcutaneous tissue. A close approximation of the subcutaneous fat with the superficial fascia is no substitute here because it cannot eliminate the elastic dermal recoil to any significant extent.
38. All scars start remodelling over a period of days and weeks and are usually fully stable at about one year. Notwithstanding the cross linking between fibers in a scar, the natural reticular pattern of normal fibrous tissues never gets replicated in a scar. As cross linking and remodelling progress, the blood supply to the area is withdrawn gradually and a red scar becomes whiter and may even get depigmented because the epithelial surface of the scar does not have the appendages of normal skin. In a majority of the Indian population however a depigmented scar is extremely uncommon and more often than not the scar might get darker, probably by migration of pigment from the surrounding skin, which is exposed to sunlight. Migration of pigment cells has been demonstrated in the treatment of vitiligo by very thin split thickness grafts and causes repigmentation of hair as well by this migration. In the Indian population the nature and the size of post-operative scars, except in some locations such as the wrist crease, the nasolabial fold or the eyelid along its fold, remain unpredictable.
39. During the process of healing some proprietary enzyme preparations have now become popular to hasten removal of slough. A variety of growth or other factors to hasten healing including the “platelet derived growth factor”, though available in the market, will require some time before a final judgment is passed about them.
40. However, incontrovertible evidence is now emerging that treatment with hyperbaric oxygen in a chamber definitely does have a beneficial effect on diabetic ulcers as well as ulcers due to peripheral vascular deficiency and may avoid amputations. A closed airtight dressing with some form of suction within it for several hours or days is also showing remarkable results in helping tardy wounds to heal. These two methods are only additional empirical aids at the present time.
Keloids and hypertrophic scars.
41. A keloid is a broad and thickened scar which invades surrounding skin and does not settle spontaneously. It is genetically influenced and must be recognized as a distinct entity from a hypertrophic scar. The latter is raised but does not spread. A scar surrounded by close cross hatched marks appears like a keloid but careful inspection will reveal its true hypertrophic nature. In burn wounds, which heal with secondary intention, raised hypertrophic scars are common. Some donor areas used for skin grafting also behave unpredictably and get raised. Pressure garments are a popular but scientifically unproven remedy (because a proper controlled trial is not possible) for such scars.
42. The treatment for keloids continues to remain unsatisfactory. Preoperative corticosteroids followed by intrakeloidal excisions followed again with post operative corticosteroids and a variety of pressure splints applied soon after surgery are known to give relief and some improvement in appearance but a cure remains elusive.