Comparison of Functional Outcomes Among Isolated Axillary Nerve Injury Patients Following Interpositional Nerve Grafting, Triceps Motor Branch Nerve Transfer and Neurolysis
Heather L. Baltzer, MD1; Michelle, F. Kircher, RN2; Robert J. Spinner, MD1; Allen T. Bishop, MD1; Alexander Y. Shin, MD1
1Department of Orthopedics, Mayo Clinic, Rochester, MN; 2Neurological Surgery, Mayo Clinic, Rochester, MN
Introduction: Isolated axillary nerve injury with resultant deltoid paralysis can be treated with a triceps motor branch transfer to the axillary nerve or interpositional nerve grafting across the damaged lesion. Currently, there is no consensus on the optimal treatment. The purpose of this study was to evaluate our experience treating isolated axillary nerve injuries and compare outcomes between different treatment methods with respect to motor function, range of motion and patient reported outcomes.
Methods: Thirty-five isolated axillary nerve injury patients that underwent operative intervention (neurolysis, interpositional grafting or triceps motor branch transfer) with at least 1 year of follow-up between 2001-2014 were retrospectively reviewed. Functional outcomes, including post-operative medical research council (MRC) grade, shoulder abduction and disability of the arm, shoulder and hand (DASH) scores, were compared using one-way ANOVA or non-parametric comparisons, as appropriate. Predictors for successful outcome (MRC ? 3), including age, body mass index (BMI), injury-to-surgery interval were also compared between groups.
Results: The most common surgical intervention was the triceps motor branch transfer (63%, 22/35), followed by interposition sural nerve grafting (20%,7/35; mean graft legth = 8.7cm, range 4-12) and neurolysis (17%, 6/35). Patients were younger in the grafting group: 24 years (s.d. 11) versus 31.5 (s.d. 17) and 49 (s.d. 22) in the transfer and neurolysis groups, respectively (p < 0.05). At a mean follow-up time of 22 months, average post-operative MRC scores were not significantly different between the transfer (3.4, s.d. 1. 3) and the nerve graft (3.9, s.d. 0.5) and neurolysis groups (4.5, s.d.1). DASH scores were significantly lower following interposition grafting compared with nerve transfer (3.9 versus 23) with no difference in shoulder abduction between groups. Successful outcome (MRC ? 3) was seen after one or more years in 100% of neurolysis and nerve graft patients and only 67% of nerve transfer patients; however this finding did not reach statistical significance (p = 0.058).
Conclusions: This is one of the larger series of isolated axillary nerve injuries. Despite being the most commonly used surgical intervention, triceps motor branch transfer does not demonstrate improved functional outcomes having the lowest average post-operative MRC score, proportion of successful outcomes (MRC ? 3) and significantly greater DASH scores. The main limitation of this study is the small number of interpositional graft patients; however, these data suggest that this technique results in similar and potentially improved functional outcomes over nerve transfer for isolated axillary nerve injury.
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