Short Notes in Plastic Surgery

May 10, 2014

45. Problems in reconstruction in cases of microtia and the case for a prosthetic ear

Filed under: Chapter 45 — ravinthatte @ 5:45 am

Background

While the preceding chapters have dealt with a two or three stage reconstruction of the ear in cases of microtia, the reality might be somewhat different for cases in which more steps might be needed to achieve the final result. The following reasons can be cited:

i.        The creation of an exact replica of the opposite ear somehow eludes the surgeon.

ii.        The cartilaginous framework, in spite of the introduction of the thin malleable stainless steel wire used to fix it, may undergo changes.

iii.        Though the cartilage has an anaerobic metabolism and normally will not be absorbed it seems to attract deposition of collagen around it when placed in the tight cavity created for reconstructing a microtic ear.

iv.        The exact auriculo-cephalic angle corresponding to the opposite ear is difficult to recreate and a surgical intervention may be required to improve it on occasions.

v.        The temporal-fascial flap used to cover the cartilage placed to create the auriculo-cephalic angle might undergo some necrosis and may need an additional skin graft after the wound granulates secondarily.

vi.        Admittedly the results of reconstruction in microtia have improved over the years but almost all the patients who undergo this reconstruction tend to cover the reconstructed ear with hair. There is satisfaction but the acceptance is not total. And this fact must be brought home to the patient in clear terms from the beginning.

In addition, in the last quarter century three major advances have been achieved in the field of surgery which need to be mentioned because they are concerned with the subject of auricular reconstruction.

  1. Tumours of the temporo-orbital region extending into the base of the skull and involving the ear, some of them malignant, are now routinely excised and the defect is either filled with a flap or covered with a split skin graft. Both are unsuitable to create an ear with a cartilaginous framework which cannot be buried under a skin graft and which will not show through a thick flap which may be employed for deep defects (Fig. 1-3).
    Slide1
  2. In burns of the face (except in acid or alkali burns) the sequelae that follow on the face are not as bad as in the past but in the area of the ear, partial or complete destruction of the cartilage of the ear is invariably followed by a skin graft which is not a suitable cover to create an ear and if a flap has been used to heal the wounds the same objection about the thickness of the flap as mentioned in the earlier para applies (Fig. 4-5).
    Slide2
  3. In craniofacial anomalies the patient undergoes major surgeries in infancy before the age of 7 years, the age at which the auricular reconstruction usually begins. Even after the cranio-facial surgery is completed, the face might not be exactly symmetrical and the creation of a new ear like the opposite member presents problems. The patient may be reluctant to undergo another series of staged reconstruction. In some of these cases the temporal-fascial flap might already have been used or its donor area violated in a bi-coronal incision and therefore an important adjunct for creation of the auriculo-cephalic sulcus is not available. A prosthetic ear is then one choice offered to the patient (Fig. 6-8)
    Slide3
  1. In addition there are patients who are reluctant to undergo the standard two or three stage surgery. Occasionally patients (particularly women) are not willing to accept a scar on the chest which follows the harvest of a cartilage.

These are some of the considerations which come to weigh when opting for a prosthetic ear.

  1. The reconstruction of a prosthetic ear has been made possible because of two elements from the earth’s crust, the metal, titanium and the non-metallic silica. Titanium is light but strong yet tensile, resists corrosion and integrates with bone without producing any adverse reactions (Fig. 9). Its alloy with aluminium increases its strength and both are individually and together not ferro-magnetic. Silicone, a polymer made from silica is inert, is available as a resin, a liquid, in rubbery form or as a malleable solid and therefore can be given a desired shape and can also be painted. It also lasts long. Basically a prosthetic ear is fashioned by first implanting titanium studs in appropriate locations to which the silicone ear is attached with clips (Fig. 10). Please see the technique in detail in the next para.
    Slide4
  2. A summary of the steps to fix the prosthetic ear is given below:

a)    Area of placement: The prosthetic ear is best placed in the area corresponding to the opposite ear on the abnormal side (as a mirror image). If both ears are missing, a comparable face to that of the patient can be used to take measurements.

b)    External auditory meatus: The area marked for the ear must have the correct relationship to the external auditory meatus when present. Occasionally the area of the meatus appears as a dimple (Fig. 11-12).

Slide5

c)    CT-Scans: If both the above are missing, a CT-scan helps to locate the mastoid cells and/or any embrylogically aborted bony canal within the temporal bone. These help to locate the position of the new ear (Fig. 13).

Slide6

d)    MRI: An MRI will help locate the course of the facial nerve. This course may be abnormal, both in cases of microtia as well as craniofacial anomalies. Incisions can then be planned to fix the titanium implants on the temporal bone (Fig. 14-15).

Slide7

e)    Quality of bone: Both CT as well as the MRI help the implantologist to determine the best site to fix the implant. The circular velocity as well as the torque of the drilling will depend on the quality of bone (Fig. 16-19).

Slide8

f)     Integration: Once the implant is fixed, the incision is closed to allow the implant to integrate with the bone. Loading of the implant with the prosthesis can begin between three to six months after the fixation of the implant (Fig. 20-21).

Slide9

g)    Fixing the healing screws: The implants are felt by fingers and small incisions are made over them to fix “healing screws” within their slots so named because they allow a scab to form around the implant which in turn gets epithelialised without blocking the slots in the implant (Fig. 22-23).

Slide10

h)    Final loading: The silicon ear mounted on a steel frame on the inside (Fig. 10) is then screwed into the slots of the titanium implant (Fig. 24-25). The case below is different from the case shown in Fig. 10.

Slide11

i)      Colour match: Any discrepancy between the colour of the implant and the face noted either by the clinician or the patient can be improved by a colour spray.

  1. Per-Ingvar Brånemark from Sweden is one of the leading pioneers in the field of implantology. The older prosthetic appliances of rubber and ivory were fixed with adhesives. Silicon prosthesis mounted on titanium implants embedded in bone came about thanks mainly to Dr. Brånemark’s efforts. He was the first to recognize the durability of titanium screws used on plates to fix fractures in the long bones and then successfully used them in the most hostile environment for any metal i.e. the mouth and then mounted teeth on them and succeeded. In an extraordinary publication in 1997 called “Craniofacial prosthesis (Quintessence Publishing Co. Inc.)” he has shown results of Implantology in the craniofacial area by an international team of experts. One look at those results was so astounding that there was no way in which some illustrations from that book could be omitted in this blog. This blog has so far not borrowed photographs from any book. All photographs in this blog have been supplied by ‘clinician contributors’ and are acknowledged. The blog has been viewed by more than 100,000 people in a short time and is likely to be seen by many more over the years and I thought the viewers should not be deprived of this treasure (Fig. 26-33). This blog is free to download and it does not generate any income and is mainly meant for students of plastic surgery. The compiler of this blog thought that the students should be made aware that such a wonderful choice is available to them in craniofacial skeletal abnormalities and this in turn will encourage the development of the science of Implantology in parts of the world where it is not in practice as yet. Here are some reproductions from the above book for which I acknowledge a huge debt. But for the internet this valuable work could not have been shared with such large numbers.

Slide12

All such implants will have problems when exposed to the atmosphere and sunlight particularly in tropical countries because of too much exposure to sunlight and dust. However, they can be repainted and / or can be reconstructed afresh as long as the titanium implants remain in place.

 

RL Thatte
Compiler, shortnotesinplasticsurgery.wordpress.com

Thanks are due to Sanjeev Deshpande, Prof. Plastic Surgery NKP Salve Institute of Medical Sciences, Nagpur and Dr. Dilip Deshpande, formerly head of Dept. of Prosthodontics, BYL Nair Memorial Dental College in Mumbai for the illustrations.

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