Clinical assessment of the ulnar nerve at the elbow: reliability of instability testing and the association of hypermobility with clinical symptoms

Abstract

Background: Ulnar nerve hypermobility has been reported to be present in 2% to 47% of asymptomatic individuals. To our knowledge, the physical examination technique for diagnosing ulnar nerve hypermobility has not been standardized. This study was designed to quantify the interobserver reliability of the physical examination for ulnar nerve hypermobility and to determine whether ulnar nerve hypermobility is associated with clinical symptoms.

Methods: Four hundred elbows in 200 volunteer participants were examined. Each participant was queried regarding symptoms attributable to the ulnar nerve. Three examiners, unaware of reported symptoms, independently performed a standardized examination of both elbows to assess ulnar nerve hypermobility. Ulnar nerves were categorized as stable or as hypermobile, which was further subclassified as perchable, perching, or dislocating. Provocative maneuvers, consisting of the Tinel test and flexion compression testing, were performed, and structural measurements were recorded. Kappa values quantified the examination's interobserver reliability. Unpaired t tests, chi-square tests, Wilcoxon tests, and Fisher exact tests were utilized to compare data between those with hypermobile nerves and those with stable nerves.

Results: Ulnar nerve hypermobility was identified in 37% (148) of the 400 elbows. Hypermobility was bilateral in 30% (fifty-nine) of the 200 subjects. For the three examiners, weighted kappa values on the right and left sides were 0.70 and 0.74, respectively. Elbows with nerve hypermobility did not experience a higher prevalence of subjective symptoms (snapping, pain, and tingling) than did elbows with stable nerves. Provocative physical examination testing for ulnar nerve irritability, however, showed consistent trends toward heightened irritability in hypermobile nerves (p = 0.04 to 0.16). Demographic data and anatomic measurements were similar between the subjects with stable nerves and those with hypermobile nerves.

Conclusions: Ulnar nerve hypermobility occurs in over one-third of the adult population. Utilizing a standardized physical examination, a diagnosis of ulnar nerve hypermobility can be established with substantial interobserver reliability. In the general population, ulnar nerve hypermobility does not appear to be associated with an increased symptomatology attributable to the ulnar nerve.

Fig. 1

Examination technique. The examiner places his or her thumb on the posteromedial aspect of the medial humeral epicondyle (red circle) at maximum elbow flexion. The patient then extends the elbow as the examiner assesses nerve stability.