Donor Nerve Selection and Outcomes of Free Functioning Muscle Transfer for Restoration of Elbow Function
Michael C. Nicoson, MD1, Michael J. Franco, MD2 and Thomas H. Tung1
1Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO, 2Plastic surgery, Washington University, St. Louis, MO
Purpose: The purpose of this study was to assess the demographics, role of donor nerve selection and functional outcomes of patients undergoing free functional muscle transfer (FFMT) for restoration of elbow flexion in an adult post-traumatic brachial plexus population. Methods: A retrospective chart review of a single surgeon's free functional muscle transfer practice over an 11 year period, 2001-2012, was undertaken. 27 total patients undergoing free functional muscle transfer for upper extremity reconstruction were identified. 5 patients were eliminated for having isolated reconstruction of either finger flexion or finger extension. Of these 22 patients, 5 patients were eliminated for having less than 6 months of follow-up – leaving 17 patients for analysis. Results: 76% (13/17) of patients undergoing FFMT were between 21-40 yrs old.76% of patients were right hand dominant (13/17), with 35% (6/17) of patients injuring their dominant side. Injury mechanisms revealed motorcycle collision (35% -- 6/17) and motor vehicle collision (41% -- 7/17) to be the most common etiologies. Of the 17 patients for whom FFMT was performed for elbow reanimation, no failures of reinnervation were noted. No patients were taken back for vascular compromise. Average time from injury to first operation was 12.8 (range 4-60) months, and average time from injury to FFMT was 29 (range 8-68) months. The utilized nerve donors for this group included the distal SAN (6 times), a combination of ICN + rectus nerves (7 times) and the MPN (4 times). Intra-operative muscle ischemia time averaged 76.2 minutes (45-180 min). Elbow flexion functional recovery was measured using the MRC grading system which showed 1 M5, 5 M4, 5 M3, 2 M2 and 1 M1 outcomes. Conclusions: Free functional muscle transfer following devastating brachial plexus injury is a powerful reconstructive option for reanimation of the upper extremity. The selection of nerve donors is of critical importance. In this series, the distal spinal accessory nerve, medial pectoral nerve, and intercostal with rectus motor nerves were all routinely used to successfully motor the transferred gracilis muscle. The medial pectoral nerve is an underutilized, highly efficacious nerve donor for FFMT. Additionally, the MPN does not require a nerve graft, allowing for direct neurotization of the transferred muscle. Long term FFMT monitoring and post-operative motor re-education is vital due to the prolonged period of reinnervation required for eventual function.
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