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Twenty four patients suffering from various ailments necessitating flap cover were treated with composite tissue transplantation by microsurgical techniques from July 1992 to July 1996. There were 21 males and 3 females in the 10 to 50 years age group. Four patients were provided flap cover on the face for congenital lesions and twenty patients required flap cover for sub acute/chronic trauma. The radial artery forearm and latissimus dorsi were the most commonly used flaps in this study. Seventeen patients had excellent and four patients had acceptable cosmetic and functional results. Three flaps were lost due to vascular problems.
The concept of composite tissue transplantation by microsurgical techniques as a method of reconstruction was first described by O'Brien in May 1973 . This in common parlance is also referred to as “Free flap” and is synonymous with micro-vascular flap. This involves complete separation of tissue along with its vascular pedicle and then its reattachment at a distant site, be it skin, muscle, nerve, bone or a combination of all of them. This has become possible in realms of surgery due to improvements in optics, development of super fine suture materials and refinements in anaesthetic techniques. Free flaps can be used to correct congenital lesions or to make good tissue losses following trauma and ablative surgery for cancer. In this study 25 patients with various reconstructive problems were treated with free tissue transfer using micro-surgical techniques. The functional and aesthetic results were evaluated post-operatively. The results so achieved were more pleasing and were achieved in much shorter time, thus saving hospital beds and ensuring early return to work place. However, even in the best of centers the success rate is 90 to 92% .
Twenty four patients, suffering from various reconstructive defects viz loss of tissue following trauma, congenital lesions and defects following ablative surgery for malignant tumours were selected for free tissue transfer by microsurgical techniques at Army Hospital (R and R) Delhi Cantt from July 1992 to July 1996. There were 21 males and 3 females. Majority of patients were in the fourth decade of life (Table 1). Trauma due to traffic accidents, missile injuries and animal bites accounted for majority of the cases (Table 2). The radial artery forearm flap and latissimus dorsi musculocutaneous flaps were the most common flaps used in this study (Table 3).
The patients selected for composite tissue transfer were explained the procedure especially in reference to the possibility of complete failure and some donor site morbidity following surgery. Once the patient agreed to undergo operation, recipient and donor vessels were assessed clinically and by Doppler flow meter studies. Smoking was stopped at least two weeks before operation. The surgery was undertaken under general anaesthesia supplemented with epidural anaesthesia where indicated. Heparin was injected just prior to pedicle clamping. End-to-end or end-to-side anastomosis was performed depending on vessel size. As far as possible two veins were preferred for better drainage. Post-operative monitoring was done by assessment of surface temperature and flap colour.
The results were graded as excellent, good, fair and poor depending upon the degree of aesthetic and functional restoration achieved after the operation. The recipient site was restored to near normal in 17 patients with minimal or nil donor site morbidity and thus results were graded as excellent. In 2 patients normal function was just acceptable therefore results were taken as good. In two patients only partial function could be restored hence the results were graded as fair. Three flaps were lost due to vascular problems so the results were taken as poor.
The loupe and microscopic magnification of tissue has made it possible to restore continuity of vessels upto 1 to 1.5 mm in diameter. The blocks of tissue containing skin, subcutaneous tissue, muscle, tendon and nerves individually or in combination can be transferred from one region of the body to the other. The surgical technique involves detachment of vascular pedicle at donor site. The block of tissue is then transplanted to another site where vascularity of the transferred tissue is restored by anastomosis of small vessels with suitable recipient vessels using microvascular technique. The procedure is known as “Composite tissue transplantation”. Since O'Brien in 1973 first used the term “Free flap” for this procedure the name has come to stay. McLean and Buncke in 1972  transferred greater omentum with meshed skin graft to cover a scalp defect. The procedure was further popularized in clinical practice by Harii and Ohmori  and Daniel and Taylor . The repair of large skin and subcutaneous defects by conventional pedicle flaps requires multiple operations in troublesome positions with prolonged hospitalization. The complications are more and cosmetic and functional results may be less than ideal. Moreover, it may not be possible to reconstruct underlying bone, muscle, tendon, or nerve defects with the conventional procedures. The free flap (Composite tissue transplantation by microsurgical technique) can be undertaken in patients with large defects not amenable to local flaps e.g. compound and infected lesions, non unions of bones or where there is necessity to repair underlying tissues such as muscles, nerves etc. Also when split skin grafts cannot be used due to avascularity and suitable pedicle flaps are not available, only free flaps can salvage the involved limb. The flaps in common use as free flaps are radial artery forearm (RAFA), latissimus dorsi (LD), rectus abdominis, scapular or parascapular, dorsalis pedis, iliac bone and fibular osteocutaneous flaps. Once the need for free flap is felt, it is obligatory to study the state of recipient and donor vessels clinically and by Doppler flowmeter. At times angiography may be essential. Thereafter, meticulous planning in reverse is undertaken. The patient should be told about the possibility of complete failure in 5 to 10% cases. However, at times transferred free tissue may “die” a slow, progressive and partial death . This is probably due to gradual ’shutting down’ of the micro-circulation by the showering of microemboli down stream from the arterial anastomosis (secondary thrombosis). It is always better to have one alternate plan in reserve in case of difficulty. It is ideal to have two surgical teams operating simultaneously at donor and recipient site each. In sub-acute cases of trauma it is better to operate in first two weeks or after six weeks. End-to-end or end-to-side anastomosis can be undertaken depending upon the vessel size and local factors.
It is safer to have two veins for one arterial anastomosis. An epidural anaesthesia/regional block supplemented with general anaesthesia (GA) minimizes chances of vasopasm which is one single factor responsible for flap loss. It has been suggested that extra-dural anaesthesia (EDA) combined with GA may have beneficial effect on perfusion in transferred free tissue due to pain relief and vasodilation that results from EDA during surgery and in the early post-operative period. Further, it has been reported that regional anaesthesia improves perfusion in replantations by preventing post-operative vasospasm. Van Twisk et al have described two patients in whom post-operative extradural block caused decreased blood flow in the free flaps . Studies in pigs have shown that EDA combined with GA does not improve microcirculatory flow in free flaps [8, 9]. During normo-volaemia, EDA causes minor drop in mean arterial pressure and decrease in micro-circulatory blood flow in flap muscle and skin. However, during slight hypovalaemia, it significantly reduces systemic blood pressure and micro-circulatory blood flow in the free flaps. Post-operatively, good state of hydration, use of low molecular weight dextran, close monitoring of flap colour and temperature and immediate re-exploration whenever needed are the key factors for the flaps survival. Not withstanding the best possible surgery and the most meticulous intra and post-operative management, free flap failures do occur in 5 to 10% cases . Therefore, it is essential to make rational selection of cases and not enlarging the indications too much. Free flaps have several advantages over the conventional flaps in that free flap is a single operation, with shorter hospitalization, post-operative freedom of movements, salvage of vital structures, possibility of flap transfer to a relatively avascular area with vascular anastomosis at a distance, with better functional and cosmetic results. It may be better to avoid free flaps in the old, infirm, athero-sclerotic and diabetic patients. The donor site for free flaps should be selected judiciously keeping in view the vessel size, pedicle length, operating time and after care in mind to avoid complications and achieve good results.