The Role of Ulnar Nerve Hypermobility in The Etiology of Ulnar Nerve Neuropathy at The Elbow – A Retrospective Cohort Study

Ulnar neuropathy at the elbow (UNE) is the second most frequent entrapment syndrome. Ulnar nerve hypermobility (UNH) has been considered an anatomical variant, but recent studies suggest it may predispose to neuropathy. We investigated the role of dynamic UNH in UNE. Does ulnar nerve hypermobility contribute to the development of ulnar neuropathy at the elbow, and can dynamic ultrasound classification of ulnar nerve instability improve diagnosis and management of UNE? A series of 220 adult patients with suspected UNE was retrospectively reviewed. All patients underwent clinical examination, bilateral dynamic ultrasound of the ulnar nerve, and nerve conduction studies and electromyography (EDX). An ultrasound-based grading of ulnar nerve hypermobility (Grade 0 = stable, Grade 1 = subluxation, Grade 2 = dislocation) was applied. UNE was confirmed in 199 patients of 220 (90.4%), 21 (9.6%) had alternative diagnoses. Ulnar nerve hypermobility was frequent among UNE patients: 55 (25%) Grade 2 and 61 (28%) Grade 1 in at least one elbow. Dynamic ultrasound of 440 elbows identified Grade 1 hypermobility in 126 elbows (28.6%) and Grade 2 in 80 elbows (18.2%), with most hypermobile nerves corresponding to confirmed UNE, supporting a strong association between increasing nerve instability and neuropathy. Dynamic ultrasound grading of nerve mobility (Grades 0-2) provided potentially useful diagnostic information. Combining high-resolution ultrasound with EDX may offer a more comprehensive diagnostic approach, particularly in cases where electrodiagnostic findings are normal despite abnormal ultrasound features. However, because this study was retrospective and lacked an internal non-UNE control group, the findings and proposed score should be interpreted as exploratory and require prospective validation before routine clinical adoption. • Ulnar nerve hypermobility may be associated with ulnar neuropathy at the elbow. • Dynamic ultrasound may detect abnormal findings even when EDX is normal. • Combined ultrasound and EDX may improve structured diagnostic assessment. • Three-grade ulnar nerve hypermobility classification is proposed.