Chapter 83. Perforasome Based Microvascular Reconstruction in Re-vascularised Diabetic Foot

In the annual meeting of the association of plastic surgeons of India held in Indore in 2023 Dr. Madhumitha Aravind presented a paper titled “Perforasome based micro vascular reconstruction in re-vascularized diabetic foot”.

The paper was presented in the competition section for trainees in plastic surgery. This paper was remarkable on three counts

1. In order to heal effects of regional vascular insufficiency (a state of persistent wound healing failure following successful revascularisation, due to chronic hypoxia induced suppression of fibro-capillary network-organ of repair) in the foot and lower leg , free flaps were harvested from other parts of the body, mostly based on perforators and their vessels, and were anastomosed to the perforators supplying the re-vascularised areas which had earlier suffered from vascular deficiency.
2. This reconstruction followed recanalization of the affected major vessels in the limb. The compiler of these short notes thought that this was an advance with which plastic surgeons in training must be familiar with and that they should be conversant with the classification of the nature of obstruction in major vessels in the lower limb in diabetics and the methods of their recanalization.
3. And equally important was the message in that paper that such reconstruction was not only meant to heal wounds but allowed the plastic surgeons to perform surgery for structural deformities in the foot so as to enable a “shoeable” foot with a reasonable bipedal walk for the patient.

The compiler of these short notes therefore had a brief discussion with Dr. Madhumitha Aravind at the venue of the conference itself followed by a questionnaire to Dr. Balakrishnan Thalaivirithan Margabandu, her mentor and the associate professor of the department of plastic surgery at the Madras medical college who had contributed to this blog earlier on another aspect of the diabetic foot. After Dr. Balakrishnan Thalaivirithan Margabandu replied to the questionnaire this chapter was compiled and was later vetted by him before uploading. The compiler of these short notes (Ravin Thatte) acknowledges with gratitude their efforts for helping write this chapter.

1. Perforator flaps are a recent advance in micro vascular surgery and the reader is referred to chapter 59 of this blog from which figures explaining the nature of these flaps ae reproduced below.

2. In the embryological development of the body which is spurred by advancing nerve tissue a capillary bed comes to be laid which later form arteries and veins and tissue develops in their midst. An arrangement comes to develop in which major trunks of both veins and arteries therefore come to supply tissue via its branches (Please see the introduction to chapter 13 of this blog titled “Flaps are a vascular network”)  These vessels penetrate and or perforate various layers and a remarkable picture of this arrangement is found in a recent edition of Gray’s anatomy which is reproduced below for the benefit of readers with due acknowledgement.

3. The same book mentions the important fact that the inferior extremity has greater number of perforators as compared to the upper extremity and is the source of the largest number of donor sites for perforator-based flaps in the body. A series of illustrations below photo shopped from Gray’s Anatomy are printed below of the vasculature of the lower limb and the location of the perforators (Figures 2, 3, 4,5, 6). The compiler of this blog acknowledges with gratitude the publishers of Gray’s anatomy.

4. The plastic surgeons must also be aware of the different gradations of the changes that occur in the vasculature of the inferior extremity in diabetic patients. A chart showing the GLASS (Global Limb Anatomic Staging system) classification is reproduced below (Fig. 7).

Fig. 7: Global Vascular Guidelines on the Management of Chronic Limb-Threatening Ischemia by Michael S Conte et al published in June 07, 2019 in European journal of vascular and endovascular surgery. Acknowledged with gratitude

This illustration gives a view of the various grades and types of the obstruction from the area of the middle thigh downwards of different severity allowing the vascular surgeon to judge the nature of intervention that might be needed to open the blood flow distally. In the case of unilateral disease a flap can be harvested from the normal opposite limb after recanalization of the vessels in affected limb. The plastic surgeon must also view angiograms of proximal vessels around the groin to decide if flaps can be harvested from that area. Here too a vascular surgeon might be able to open affected vessels to allow such a harvest.  Many of these donor flaps can also be based on corresponding perforators. Typically in diabetics, regional vascular insufficiency is confined only to lower limbs, for the following reasons.

1. Arterioles of lower limbs generally have higher tone and resistance.
2. There is loss of sympathetic mechanical chemo-myo autoregulation of microcirculation in the lower limb-s of diabetics.
3. Chronic hypoxia induced inhibition of fibro-capillary network called regional vascular insufficiency is pronounced only in lower limbs in diabetics, as shown by Balakrishnan the main contributor of this chapter  in his  study. So harvesting at the hip or above hip level perforasome effectively heals the regional vascular insufficiency (RVI) in the penumbra region of ischaemic ulcers producing sound healing following revascularisation. The term penumbra refers to the zone adjoining the main area of complete devascularisation  

5. The recanalization of the affected vessels can be done by various methods. A block can be extracted, the vessel can be dilated by a balloon (intraluminal) or by creating sub-intimal channel or bypass is effected by a vein graft.  

Dr. Paresh Pai a leading vascular surgeon from Mumbai in the state of Maharashtra in India was requested by the compiler of these short notes to elaborate on this subject and his introductory note and explanatory diagrams are reproduced below. The compiler of this blog thanks him for his contribution   

Wounds or injury to any tissue in the body requires additional nutrition to heal. The additional requirement usually met by increase in blood supply through means of tissue factors. When there is a blockage within the artery this additional supply may not be met and may result either in slow or poor healing or tissue damage with necrosis.  A large defect may need some kind of skin cover that could be obtained in some situations by the use of a vascular flap that uses a pedicle for arterial supply and venous drainage. As mentioned above, an obstruction to free flow to the tissue or flap results in a deficit in the blood supply that needs to be corrected urgently to ensure viability of the flap and quick healing.

Various techniques may be used to either remove or cross or bypass the obstruction depending on the vessel involved, site and length of obstruction and long-term patency of the feeding artery.

Blockages may be removed by using the following methods.

Open surgical endarterectomy where the localised plaque is scrapped off and the  “arteriotomy” closed with a patch.

Or endovascular methods using a Directional “Atherectomy” device to shave off the obstructing plaque

Or a combination of endovascular & open procedure (hybrid) if the site of obstruction is remote or not easily accessible using a ring “endarterectomy device C1” to remove a long plaque and keep the intimal flap anchored with a stent.

Blockages may be crossed using a endovascular techniques using a wire followed by ballooning to open up the arterial obstruction with an angioplasty balloon with or without stent

The obstruction may be crossed with the wire by either going through the narrowed lumen of artery (intra-luminal) or underneath the plaque present within the intima (sub-intimal) before the arterial lumen is ballooned out.

At times the blockage may be bypassed using a surgical segmental by-pass as below. The block is shown by a horizontally striated patch in pink and black. The vein graft has to be reversed in order to enable a distal flow. The figure shows a perforator from the diseased artery now re-canalised, on which a flap is vascularised to heal the earlier de-vascularized area.

1. A combination of the causes of micro -angiopathy in diabetics has been covered in an earlier chapter with a diagram which is reproduced here. (Chapter 80 figure 8 is reproduced below). 

Generally speaking, regional vascular deficiency in diabetics, particularly   in the foot has to with lack of compliance of the micro circulation both to pressure and lack of oxygen. In the former the vessels tend to take time to return to their calibre and in the latter they fail to dilate in the presence of poor oxygenation and therefore fail to increase blood supply to the affected part. In addition, the reduction in the flexibility of the RBCs, poor leucocyte function and deleterious effects on the levels of serum albumin contribute adversely to the reparative ability of tissue. In short, the fibro-capillary network also called the “organ of repair” suffers over the long term and takes time to recover. It is in front of this background that just by improving the flow to the affected part healing can’t be accelerated immediately but requires tissue in the area of that ‘perforasome’ to be replaced by a free flap consisting of healthy tissue.

2. In regional vascular insufficiency the area is also marked by perivascular fibrosis both proximal and distal to the area that is affected and requires to be released at the time of reconstruction.
3. Successful procedures of revascularisation is marked by the blush phenomena and investigations such as angiography after the procedure reveal two or three vascular arches around the ankle and the foot and the perforators in the involved area.
4. The wound or the affected part as mentioned earlier is recalcitrant and requires careful limited debridement of obviously dead tissue but care is taken to preserve tissue which appears salvageable.   Wet dressing and\or topical negative pressure therapy help in improving the wound physiology. Appearance of granulation tissue and absence of discharge as well as absence of any increase in the affected area are indications for performing a flap with the distal perforator and avoids steal phenomena which might occur if a major vessel is used as a donor vessel. This is the advantage of “Involved Perforasome Directed Distal Reconstruction”.
5. The ultimate idea of “perforasome” based reconstruction is to provide “shoeable” foot or foot residue                                                                 
6. Some clinical examples of “perforasom” based flaps in difficult situations are reproduced below with legends or with necessary information
   • 58 year old female with chronic limb threatening ischaemia(CLTI) of left diabetic foot with medial and lateral calcaneal perforasomes involved
   • Targeted pathway for the revascularization of the above perforasomes
   • 6 weeks post revascularization status
   • Perforasome‑directed reconstruction using the anterolateral thigh flap
   • One‑year postoperative result

66-year-old male with ischemic diabetic foot treated by hybrid procedure showing granulation on 20th day post op. Treated by primarily thinned thoracodorsal artery based latissimus dorsi muscle flap with split skin graft.

Primary thinning of muscle flap done.

18 months follow up with “shoeable” and stable foot.

60-year-old female with diabetic foot – with chronic limb threatening ischemia (CLTI), who after debridement had under gone involved “perforasome” directed distal re-vascularization (IPDDR) angioplasty for severe tibial disease

3rd toe salvaged and reconstructed with free radial forearm flap (18 months post op picture)

64-year-old male patient, on 15th day following involved “perforasome” directed distal revascularization (IPDDR) of left foot showed severe and recalcitrant regional vascular insufficiency (RVI) which was treated by modified Pirograff amputation

Repeat computed tomography angiogram (CT angiogram) showed straight line flow to foot on left side and confirmed regional vascular insufficiency (RVI) and disease free profunda system on contralateral thigh seen.

Following Pirograff amputation and negative pressure wound therapy, after good granulation appeared-Free anterolateral thigh flap was harvested with lateral cutaneous nerve of thigh.

Stump salvaged with anterolateral thigh flap (Neurotized to superficial peroneal nerve)

1 year follow up with stable stump rehabilitated with prosthesis.

62-year-old female with diabetic left foot with chronic limb threatening ischemia (CLTI) and little toe-wet gangrene

X-ray shows Charcot’s degeneration of calcaneum and angiogram reveals popliteal block with tibial disease

Free medial plantar artery flap (the contralateral foot had preserved arch and disease free) used for calcaneal defect and except little toe rest of foot was salvaged (12 months post op).