Traumatic major muscle loss in the upper extremity: reconstruction using functioning free muscle transplantation

Traumatic crushing injuries of the muscle compartments will occasionally cause major muscle or muscle-group loss with concomitant irreparable nerve injuries. Those cases with or without the availability of local muscle transfers form another indication for functioning free muscle transplantation (FFMT). The authors report their experience with 20 FFMTs in 14 patients with severe muscle loss from 1986 to 1996. They were selected because all their major muscle loss was primarily due to muscle avulsion, avascularity, and necrosis, but not secondarily due to nerve injury or ischemic injury. The motor nerves innervating these muscles were either disrupted after muscle debridement or avulsed from the neuromuscular junction concomitantly. The initial injury in this series was so severe that in many cases amputation was advised. Fractures were present in almost half the cases (6/14). Half the cases required revascularization due to rupture of major vessels (7/14), and the need for free-tissue transfer for soft-tissue coverage was demonstrated in over two-thirds (8/14). All FFMTs were innervated by the motor nerve which originally innervated the lost major muscle(s), and to replace palmar arm compartment (elbow flexors, 6 cases), palmar forearm compartment (finger flexors, 6 cases), and dorsal forearm compartment (finger extensors, 8 cases). Postoperative follow-up ranged from 3 to 12.5 years (average: 8.3 years). The success rate, i.e., achieving M4 muscle strength, was nearly 90 percent (18 of 20 FFMTs). Two cases with sub-optimal results were performed in the acute stage for the purpose of soft-tissue coverage and functional results. These reconstructions make the originally compromised limb useful for most activities of daily living. This type of injury should be recognized as providing a good prognosis after application of the FFMT, and arbitrary amputation should be avoided.