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

Marijuana is often used by patients with peripheral nerve injuries for pain management, but its impact on nerve transfer surgery outcomes remains unexplored.

This retrospective cohort study reviewed the records of patients age 18 years and older who underwent radial-to-axillary or ulnar fascicle to biceps fascicle (Oberlin) nerve transfers at a single institution from 2014 to 2023. Data collected included demographics, surgical details, injury characteristics, marijuana use, and Medical Research Council strength scores from preoperative evaluations to 24 months after operation. Statistical analyses were performed using χ² tests and analysis of variance.

Forty-nine patients' (67 surgeries, 42 males, mean age 43.3 ± 17.3 years) records were analyzed. Radial-to-axillary nerve transfer and Oberlin transfer were performed in 18 patients. Radial-to-axillary nerve transfer was performed in 38 patients, and Oberlin transfer was performed in 29 patients. No significant differences were found regarding marijuana use and achievement of functional strength at 6, 12, 18, or 24 months postoperatively. No significant associations were found controlling for the type of surgery. Patients showing notable improvement between 6- and 24-month intervals and the preoperative and 24-month intervals were significantly younger than those without improvement (P = .03 and P = .001, respectively). Compared with patients who did not improve in functional strength, patients achieving functional strength by 24 months postoperatively had a shorter interval between injury and surgery (0.7 ± 0.3 years vs 1.7 ± 2.5 years, P = .01).

In patients undergoing radial-to-axillary nerve transfer or Oberlin nerve transfer surgery, marijuana use did not influence functional strength outcomes. Improvement in functional strength was associated with younger age and shorter time between injury and surgery.