Poster 176: Distal Mononeuropathy and Nerve Release after Arthroscopic Shoulder Surgery: A Matched Cohort Analysis

OBJECTIVES: Following arthroscopic shoulder procedures such as total shoulder arthroplasties, reverse total shoulder arthroplasties, and rotator cuff repairs, select patients have presented with symptomatic distal mononeuropathy (DMN) that require follow-up nerve release procedure(s). This occurrence may be secondary to operative complications such as limb traction, surgical dissection, hematoma formation, or interscalene block placement. Separately, many patients presenting for impending shoulder procedures have been found to have preexisting DMN that similarly require nerve release for management. This retrospective cohort study aims to compare the clinical outcomes of a cohort of patients who underwent peripheral nerve release (cubital/carpal tunnel) for DMN following recent shoulder surgery to a cohort with no prior history of a shoulder procedure before DMN presentation. METHODS: From 2010 to 2020, CPT codes were used to identify a cohort of patients over the age of 18 who underwent a shoulder procedure (rotator cuff repair, total shoulder arthroplasty, reverse total shoulder arthroplasty, and shoulder stabilization) and had an ensuing nerve release procedure for DMN (open or endoscopic cubital or carpal tunnel release) within 2 years of that surgery. A second cohort of patients who underwent a nerve release procedure for DMN presentation (open or endoscopic cubital or carpal tunnel release) with no prior history of shoulder surgery were identified using CPT codes and subsequently matched to the first cohort by age, sex, and BMI in a 3:1 (control: case) ratio. Following this, chart review and Redcap surveys were used to collect: demographics, surgical history, electromyography/nerve conduction velocity (EMG/NCV) results, post-operative symptoms (numbness, weakness, pain), and patient-reported outcomes (ASES, SANE, DASH). EMG/NCV results were categorized as Mild/Moderate/Severe based on standard practices. T-tests and Mann-Whitney tests were used for statistical analysis between the two groups with significance set at P < .05. RESULTS: 120 patients are included in this analysis (28 case, 92 control). There was no statistical difference between the groups for mean age at surgery, sex, or BMI . Patients with prior shoulder surgery before DMN presentation had a nerve release at an average of 0.81 ± 0.61 years after shoulder surgery. Mean follow-up time after nerve release for all patients in both cohorts was 4.91 ± 2.11 years. The most common nerve release for DMN across both cohorts was open carpal tunnel release (n=86), followed by endoscopic carpal tunnel release (n=22), open cubital tunnel release (n=16), and endoscopic cubital tunnel release (n=2). There was no statistical difference in preoperative EMG/NCV results between patients in the case group (39.3% mild, 32.1% moderate, 28.6% severe) compared to patients in the control group (29.3% mild, 47.8% moderate, 22.8% Severe) (P=0.125). There was no difference between groups for preoperative ASES, SANE, and DASH (P≥0.188), or for postoperative ASES, SANE, and DASH (P≥0.170). Following nerve release, patients in the case group were found to have significantly more post-operative numbness/tingling (42.9%) than patients in the control group (18.5%) (P=0.017). There was no difference between groups in postoperative pain (P=0.075) or weakness (P=0.156) [Figure 1]. Residual post-operative numbness following nerve release, was more likely to occur in the forearm for patients in the case group (21.4%) than patients in the control group (6.52% of patients) (P=0.032) [Figure 2]. Although not significant, 65.2% of patients in the case group reported complete resolution of symptoms following nerve release procedure compared to 50% of patients in the control group (P=.219). CONCLUSIONS: Patients with a history of shoulder surgery prior to presentation of DMN are more likely to experience persistent numbness or tingling after nerve release surgery than patients without a history of shoulder surgery. These patients are also more likely to experience symptoms located in the forearm. However, patient-reported outcomes between patients undergoing nerve release surgery with a history of shoulder surgery and those without are similar. Surgeons should be aware of these findings for improved patient education regarding post-operative prognosis.