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Unlabelled: Avulsion injuries have a poor prognosis for survival in clinical replantation surgery. Arterial thrombosis is the most significant factor contributing to avulsion replant failure, and severe arterial damage has been observed with this injury. However, patency rates of experimentally avulsed arteries repaired immediately are much higher than in the clinical situation. This paper evaluates the effect of an added component--ischemia--on the patency of experimentally avulsed arteries. All avulsions seen clinically are subject to some degree of ischemia prior to replantation. Ninety rabbits had both femoral arteries avulsed under general anesthesia. A 6.5-cm graft was harvested from the left distal femoral artery. In 20 rabbits (group 1: 0 hours of ischemia) the graft was immediately inserted into the defect in the right femoral artery. Sixty rabbits (20 grafts per group) had their grafts stored at 4 degrees C for either 10 hours (group 2), 18 hours (group 3), or 24 hours (group 4) and reinserted into the right femoral artery in a second operation. Patency was assessed 3 weeks after reinsertion. Groups 1 and 2 maintained high patency rates (85 percent); however, group 3 (70 percent) and group 4 (45 percent) had lower patency rates than group 1, with a significant difference between groups 1 and 4 (p < 0.01). In a fifth group (10 grafts), avulsed 24-hour ischemic grafts were hydrodilated prior to reinsertion. The patency rate of this group increased significantly (90 percent) compared with group 4 (p < 0.005)., Conclusion: These experiments suggest that a combination of avulsion injury and ischemia time is responsible for the poor clinical results of avulsion replantations.

Between 1970 and 1978, 160 digits in 120 patients were replanted or revascularized. One hundred and nineteen digits survived, and these patients were assessed objectively and subjectively for functional results and their ability to return to work. Providing that strict indications are observed, long term objective and subjective results of digital replantation have proved most valuable from the point of view of the examiner and the patient. The best results were obtained with replantation of the thumb.

The functional results in 25 of 30 patients after successful upper limb revascularization or replantation were evaluated by subjective-patient surveying and objective measurements. Young patients with complete, sharply amputated extremities at the wrist level or those with incomplete injuries and uninjured peripheral nerves had the best functional results. Multiple-level, diffuse crush, or avulsion injuries, even if the injuries were incomplete, and patients with high-level nerve injury had less return of function.

In a series of 130 digital replantations successful revascularization has been obtained in 74% of cases. Arterial thrombosis is the most common cause (65%) of all failures. A useful digit can be obtained following replantation and the surgery is particularly indicated for amputated thumbs and in hands suffering multiple injuries. Precautionary measures against bleeding are absolutely essential. Primary tendon and nerve repairs are advocated. Vascular occlusion may be corrected by revisional surgery and secondary surgery can improve tendon nerve or joint function.

An analysis of the first 130 cases of digital revascularization and replantation performed at St Vincent's Hospital, Melbourne, during the period 1970-1977, confirms the long-term functional value of these procedures provided that strict indications for replantation are adhered to. Patient satisfaction has been almost universal, and objective testing shows that the most satisfying aspect of the procedure is the quality of sensory return. Flexor tendon function and the range of joint movement, however, are universally poor, and all patients complain of sensitivity to cold. The thumb has been by far the most satisfactory digit to replant, and avulsion injuries gave the poorest results, from the point of view of both survival and long-term function.

A segment of tibia 4.5 centimetres long was removed from one hind limb of fifteen dogs. It was then replaced and the main vasculature was restored by a microsurgical technique. In eight controls the segment was replaced without such restoration. In two-thirds of the former cases the microvascular reconstruction was successful; the rate of infection was found to be reduced, bone union was guaranteed and the rate of union accelerated. Success or failure of the reconstruction was clearly demonstrated in five cases by early bone scanning using technetium-labelled polyphosphate.

Although the operating microscope was introduced more than 50 years ago, its use was at first confined to otolaryngology and, later, to ophthalmology. More recently its use in the development of microvascular techniques has led to spectacular advances in the field of replantation and reconstructive surgery. The organization of microsurgical research at St Vincent's Hospital, Melbourne, is briefly described and clinical experience at this hospital over the past 10 years is reviewed. This includes 86 cases of digital replantation, with survival rates of 58% for complete and 82% for incomplete amputation, and 14 cases of major replantation (amputations proximal to the metacarpophalangeal joints) with a survival rate of 71%. In the second part of the lecture the use of microsurgery for composite tissue transfer and one-stage toe-to-hand transfer is discussed and experimental and clinical experience in microlymphatic surgery described.

An unabridged series of 73 thumb amputations subjected to replantation or revascularization surgery in the years 1971 to 1980 has been examined in detail as a combined prospective and retrospective study to determine the factors playing a role in survival and failure. The causes of failure and complications are demonstrated. The overall failure rate was 27%. The factors influencing the outcome were: the injury--mechanical type and degree of amputation; the patient--age and amputation level; and the surgeon--frequency of utilization of vein grafts. The highest failure was seen in the complete amputation with avulsion/diffuse crush injury group (63%). Incomplete amputations had the lowest failure rate, particularly if the injury type was guillotine/local crush and at a level proximal to the metacarpophalangeal joint. Patients aged 11 to 20 years had a low failure rate (18%) whereas children under 5 years had a high failure rate (40%). Arterial thrombosis was the most frequent complication and cause of failure. The surgeon could modify the result by frequent use of vein grafts for arterial reconstruction and by reoperation for thrombotic complication. Five thumbs failed to revascularize at the primary operation and were removed at this primary operation.

One hundred digital replantations and revascularizations of digits performed during a five year period were analyzed. Seventy replantations (70 per cent) survived and 62 were available for long term functional follow-up. Provided strict indications are observed, replantation is a most worthwhile procedure.