Although many investigators have been attempting autogenous transplantation of skeletal muscle since 1800, successful transplantation has not been achieved. A completely isolated muscle transplant without blood supply usually develops entire necrosis within a few days and is replaced by fibrous tissues. Through canine experiments on limb replantation started in May, 1960, I found that muscles in the successfully replanted limb survived and worked well after proper reinnervation. From these experiments, the idea of free muscle transplantation flashed through my mind; if a muscle is transplanted with re-establishment of its neurovascular supply by microsurgical anastomoses, it will probably survive and function after reinnervation.

The skeletal muscles can be divided into several types, according to the anatomic variations of their neurovascular supply. For transplantation, a muscle with a single neurovascular bundle was thought to be the best donor muscle. Our anatomic studies in dogs revealed that the rectus femoris muscle, sartorious muscle, gracilis muscle, biceps brachii muscle, and gastrocnemius muscle were suitable donors. Canine experiments were started, using the rectus femoris muscle. In 60 mongrel dogs, the rectus femoris muscle was completely isolated with its neurovascular bundle and transplanted to the contralateral thigh, into the defect created by removal of the rectus femoris muscle (heterotopic transplantation on 20 dogs) or reimplanted in the same place (orthotopic reimplantation on 40 dogs.) Because of the unfavorable suture materials and unskilled microsurgical technique available at that time, the success rate was 70%. The successfully transplanted muscles were examined histologically with light microscopy and electron microscopy, and the functional recovery was checked using evoked potentials and electromyograms. Of 60 dogs, 42 were followed for 3 to 18 months. After 5 months, the transplanted muscle appeared nearly normal in structure, and EMG studies indicated satisfactory reinnervation. l

Several important points should be considered:

1. Selection of donor muscle. A spindle-shaped skeletal muscle with a single artery, vein, and nerve supply is best to produce a single motion, but if one wishes to reconstruct multiple motions, a large muscle, such as the pectoralis major muscle, which has several neurovascular supplies, can be used.

2. Recipient condition. The recipient site should have a suitable artery, vein, and nerve to be anastomosed to the donor muscle. The recipient nerve should be pure motor nerve; if not, histochemical or bioassay technique for funicular identification should be used, and funicular suture to the motor portion of the nerve should be done.

3. After the transplantation, the tension in the grafted muscle is important. The (tension) length in the rest position in situ should be measured before the origin and insertion are sectioned and this length should be reestablished after transplantation.

4. The joints in the recipient limb should have a sufficient range of passive motion.

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