Does Age Predict Outcomes of Triceps to Axillary Nerve Transfer?

PURPOSE: Factors influencing the results of radial nerve to triceps to axillary nerve transfers remain poorly defined. Therefore, the goal of this study is to compare radial to axillary nerve transfer outcomes by age, and to determine if age is a reliable predictor of outcome.

METHODS: A single center retrospective cohort study was conducted between 2015 and 2025. Exclusions included patients younger than 18 years, less than 1 year follow-up, or lack of MRC strength documented after surgery. Patients were subanalyzed by age: 18-39 years, 40-59 years, and ≥60 years. The primary outcome was recovery of M4 strength or greater. Subgroup analysis was performed to compare demographic, intraoperative variables, and postoperative outcomes.

RESULTS: Fifty-three patients (n = 20 aged 18-39 years, n = 16 aged 40-59 years, n = 17 aged ≥60 years) were included with a median follow-up time of 16.7 months. There were no differences in lesion location, BMI, smoking status, or preoperative MRC grade between groups. Younger patients were more likely to sustain high-energy injuries (85% in patients aged 18-39 years, 43.8% in patients aged 40-59 years, 17.6% in patients aged ≥60 years, P = .001). 62.3 % of the cohort underwent end-to-end nerve transfer (75% in patients aged 18-39 years, 68.8% in patients aged 40-59 years, 47.1% in patients aged ≥60 years, P = .214). Postoperative clinical improvement was demonstrated in every age group. Overall, 77.4% of patients had a preoperative deltoid M0 strength and 66.0% of patients achieved at least M4 strength after surgery (75% in patients aged 18-39 years, 68.8% in patients aged 40-59 years, 52.9% in patients aged ≥60 years, P = .304). After surgery, there was no difference between groups for donor site morbidity, reoperation rate, or wound complications.

CONCLUSIONS: Meaningful M4-M5 recovery was achieved across all age cohorts, with a nonsignificant trend toward lower recovery rates in older patients (P = .746). Although not significant (P = .260), ETE trended toward being more common in younger patients versus ETS in older patients, likely reflecting injury severity. Patients that had therapeutic stimulation were 2.75 times more likely to reach M4-M5 compared to those that did not.

TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic III.