Faculty Bibliography

PURPOSE/OBJECTIVE:To evaluate the relative axonal match between potential donor and recipient nerves, so that maximal reinnervation potential may be reached with the least chance of donor site morbidity. METHODS:In 10 fresh-frozen cadaveric specimens, the main trunk and anterior, posterior, sensory and teres minor branches of the axillary nerve were identified, as were the radial nerve branches to the long, medial, and lateral heads of the triceps. The swing distances of the triceps fascicular nerve branches and the axillary nerve branches relative to the inferior border of the teres major muscle were recorded. Histomorphological analysis and axon counts were performed on sections of each branch. RESULTS:The median number of axons in the main axillary trunk was 7,887, with 4,052, 1,242, and 1,161 axons in the anterior, posterior, and teres minor branches, respectively. All specimens had a single long head triceps branch (median, 2,302 axons), a range of 1 to 3 branches to the medial head of the triceps (composite axon count, 2,198 axons), and 1 to 3 branches to the lateral head of the triceps (composite average, 1,462 axons). The medial and lateral head branches had sufficient swing distance to reach the anterior branch of the axillary nerve in all 10 specimens, with only 4 specimens having adequate long head branch swing distances. CONCLUSIONS:It is anatomically feasible to transfer multiple branches of the radial nerve supplying the medial, lateral, and sometimes, long head of the triceps to all branches of the axillary nerve in an attempt to reinnervate the deltoid and teres minor muscles. CLINICAL RELEVANCE/CONCLUSIONS:Understanding the axon counts of the different possible transfer combinations will improve operative flexibility and enable peripheral nerve surgeons to reinnervate for both abduction and external rotation with the highest donor/recipient axon count ratios.

BACKGROUND:Nerve transfer surgery has revolutionized the management of traumatic brachial plexus injures. However, the optimal size ratio of donor to recipient nerve has yet to be elucidated. The authors investigated the axon count ratios of ulnar and median fascicular transfers to restore elbow flexion. The authors hypothesized that donor nerve axon counts would be correlated with historical success of various nerve transfers used to restore elbow flexion. METHODS:Ten cadaveric specimens were used for a histomorphologic analysis of fascicular nerve transfers. Review of previously published axon counts and clinical results following transfer to the musculocutaneous nerve to restore elbow flexion was performed for the following donor nerves: medial pectoral, spinal accessory, intercostal, thoracodorsal, ulnar, and median fascicular. RESULTS:The average number of fascicles identified was 7.9 in the ulnar nerve and 8.0 in the median nerve. The mean fascicular axon count was 1318 for the ulnar nerve and 1860 for the median nerve. Mean recipient nerve axon count was 1826 for the musculocutaneous biceps branch and 1840 for the brachialis branch. A significant correlation between axon count and clinical results of transfers to restore elbow flexion was observed. Donor-to-recipient nerve axon count ratios below 0.7:1 were associated with a decreased likelihood of a successful outcome. CONCLUSIONS:In nerve transfers to restore elbow flexion, an appropriate size match between donor and recipient nerves appears to be a factor affecting clinical success. These data support a donor-to-recipient axon count ratio greater than 0.7:1 as the goal for brachial plexus nerve transfers to restore elbow flexion.

PURPOSE: To assess the results of a hybrid Russe procedure using a corticocancellous strut, cancellous autologous nonvascularized bone graft, and cannulated headless compression screw to reduce the deformity reliably from a collapsed scaphoid nonunion, provide osteoinductive stimulus, and stabilize the fracture for predictable union. METHODS: A hybrid Russe procedure was performed for scaphoid waist fracture nonunions with humpback deformity and no evidence of avascular necrosis. A volar distal radius autologous bone graft was harvested and a strut of cortical bone was fashioned and placed into the nonunion site to restore length and alignment. We packed cancellous bone graft in the remainder of the nonunion site and fixed the scaphoid was with a headless compression screw. Union was determined by radiographs or computed tomography, and intrascaphoid, scapholunate, and radiolunate angles were calculated on final radiographs. We recorded wrist range of motion, grip strength, pinch strength, pain, and complications. RESULTS: Fourteen male and 3 female patients (average age, 32 years; range, 16-78 years), with a mean follow-up of 32 months, were examined clinically and radiographically. All 17 scaphoids united with a mean time for union of 3.6 months. The mean postoperative intrascaphoid angle was significantly reduced from 65 degrees preoperatively to 35 degrees postoperatively. The mean radiolunate angle was significantly improved from 20 degrees from neutral (lunate tilted dorsally) preoperatively to 0 degrees postoperatively. The scapholunate angle also demonstrated significant improvement from 70 degrees preoperatively to 56 degrees postoperatively. Grip strength improved from 70% of the contralateral hand to 89% after the procedure. All patients were satisfied with the functional outcome and no donor site morbidity or hardware issues were identified. CONCLUSIONS: This straightforward hybrid Russe technique predictably restored radiolunate, scapholunate, and intrascaphoid angles with a 100% union incidence. The technique provides excellent functional results in patients with a challenging clinical problem, and we recommend it for scaphoid fracture waist nonunions with dorsal intercalated segment instability deformity. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

PURPOSE/OBJECTIVE:We hypothesized that health of the donor nerve and corresponding muscle, as assessed by electromyography (EMG), could predict the outcome of nerve transfer surgery. METHODS:A retrospective review was performed to investigate outcomes of nerve transfers for elbow flexion and shoulder abduction. Motor strength was graded preoperatively and after a minimum 1-year follow-up. Preoperative EMG results were classified as functionally normal or affected based on motor unit recruitment pattern and correlated with follow-up motor strength and range of motion. RESULTS:Forty nerve transfers were identified: 27 were performed for elbow flexion and 13 for shoulder abduction. Overall, the 29 transfers in the normal EMG cohort showed significantly greater postoperative improvement in motor strength (Medical Research Council grade 0.2-4.1) than the 11 transfers in the affected EMG cohort (grade 0.0-3.0). In the shoulder cohort, normal donor nerves resulted in greater strength (grade 4.0 vs. 2.4) and active motion (83° vs. 25°) compared with affected donor nerves. Double fascicular transfers with 2 normal donor nerves demonstrated improved strength compared with double nerve transfers when 1 donor nerve was affected (grade 4.5 vs. 3.2). CONCLUSIONS:Our findings demonstrate that a simple EMG classification that describes the quality of donor nerves can predict outcome as measured by postoperative motor strength and range of motion. Preoperative EMG evaluation should be considered a valuable supplementary component of the donor nerve selection process when planning brachial plexus reconstruction. TYPE OF STUDY/LEVEL OF EVIDENCE/METHODS:Prognostic II.