The Impacts of Marijuana Usage on Nerve Transfer Outcomes: A Retrospective Cohort Study.

Lee J.; Kamar Z.; Solomon S.; Lee D.; Johnson S.; Albdewi M.; Saadeh Y. · Neurosurgery practice · 2026

**Background & Methods** This retrospective cohort study analyzed 49 patients (67 surgeries) who underwent radial-to-axillary or Oberlin nerve transfers between 2014-2023 at a single institution. Researchers collected demographics, surgical details, injury characteristics, marijuana use status, and Medical Research Council strength scores from preoperative evaluation through 24 months postoperatively, with statistical analysis performed using χ² tests and analysis of variance. **Key Findings** • Marijuana use did not significantly influence functional strength outcomes at 6, 12, 18, or 24 months postoperatively, with no significant associations found when controlling for surgery type (radial-to-axillary vs. Oberlin transfer). • Patients achieving functional strength improvement by 24 months had significantly younger age (P = .03 for 6-24 month improvement; P = .001 for preoperative-24 month improvement) and shorter time from injury to surgery (0.7 ± 0.3 years vs. 1.7 ± 2.5 years; P = .01) compared to those without improvement. • Age and timing of surgical intervention were the only statistically significant predictors of functional recovery, suggesting these factors are more clinically relevant than cannabis use for nerve transfer outcomes. **Dosage & Administration** Not reported. The study documented marijuana use status but did not specify frequency, dose, cannabinoid composition, or route of administration. **Safety & Adverse Effects** Not reported. The study focused on functional outcomes rather than safety profiles or adverse events related to marijuana use in this surgical population. **Evidence Quality** This retrospective cohort study represents Level 3 evidence with several limitations: single-institution design limits generalizability, modest sample size (n=49), lack of standardized marijuana use documentation, potential unmeasured confounders, and absence of randomization or control group. The binary classification of marijuana use (yes/no) provides limited granularity regarding exposure intensity or timing relative to surgery. However, the study addresses a clinically relevant gap by examining cannabis's impact on surgical outcomes in peripheral nerve repair. The 24-month follow-up period with standardized strength assessments strengthens outcome measurement validity.

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