The Role of Length of Nerve Grafts in Combination with Free Functional Muscle Transplantation for Brachial Plexus Injury: A Single-Center Experience.

Purpose: Extensive lesions of the brachial plexus, or late cases, require free functional muscle grafts because the expected recovery time exceeds the critical threshold of 1.5 years, beyond which irreversible damage may be expected in the distal nerve stump and in the muscle. The reconstructive concept consists of a two-stage procedure where, in the first step, a nerve transfer is performed (from ipsi- or contralateral donor nerves). In the second step, after successful axonal regeneration within the graft has been confirmed, a free muscle transfer is performed. These grafts often exceed 40 cm in length, particularly for contralateral transfers. The purpose of this study was to assess whether robust motor recovery could be supported by such long nerve grafts.

Methods: From April 2004 to April 2023, a total of 327 free functional muscle transfers were performed, the nerve graft length ranging from 0 cm (direct coaptation) to 90 cm (serial grafts). Motor recovery was evaluated 1.5 years after surgery according to the MRC scale.

Results: A total of 208 patients were available for follow up. Direct coaptation yielded the best results, with 83% of patients reaching an M3 or M4 level of muscle strength. With the application of long (30-60 cm) grafts, 73% of the patients were classified as M3 or M4. The application of serial nerve grafts, however, only resulted in 18% of patients achieving a motor recovery rating of M3.

Conclusions: These findings demonstrate that robust motor regeneration is supported by long (30-60 cm) nerve grafts, whereas serial nerve grafting results in a marked reduction in the quality of regeneration.