Classification and Treatment of Ulnar Nerve Subluxation Following Endoscopic Cubital Tunnel Release

PURPOSE: Endoscopic cubital tunnel release (ECuTR) is an effective procedure to alleviate cubital tunnel syndrome. To improve patient outcomes and lessen concerns regarding ulnar nerve subluxation (UNS) after ECuTR, the current study proposes an intraoperative UNS classification system and subsequent treatment protocol. We present a preliminary report of patients treated under these guidelines. METHODS: We retrospectively reviewed 87 patients (100 ECuTRs). Nerve mobility was classified during surgery, in which grade 1 = no movement or partial subluxation; deep retrocondylar groove and/or no generalized hypermobility (no further intervention); grade 2 = partial subluxation; shallow retrocondylar groove and/or inherent generalized hypermobility (required medial epicondylectomy); and grade 3 = complete anterior dislocation (required medial epicondylectomy or anterior transposition). Clinical outcomes at final follow-up (mean ± SD, 34 ± 20.3 weeks; range, 5–89 weeks) were collected and included Disabilities of the Arm, Shoulder, and Hand questionnaires, visual analog scale pain score, grip and pinch strength, 2-point discrimination, and range of motion. RESULTS: We report 37 patients (42 cases), grade 1 (n = 30), grade 2 (n = 1), and grade 3 (n = 11). Gross grip strength, lateral, 3-jaw chuck, and precision pinch strength recovered 87%, 90%, 105%, and 87%, respectively. Wrist and elbow range of motion returned to normal limits, 2-point discrimination improved to normal scores at final follow-up, Disabilities of the Arm, Shoulder, and Hand scores were reduced from 59.8 before to 29.9 after surgery, and visual analog scale pain score improved from 7.2 before to 2.5 after surgery (P < .001). CONCLUSIONS: To our knowledge, this is the first study to classify UNS after ECuTR and describe a guideline for ensuing treatment. Our preliminary report of patients shows satisfactory outcomes, which suggests that our intraoperative UNS classification system has promise in preventing adverse complications of ulnar nerve hypermobility after ECuTR. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.