Ultrasonographic prevalence of ulnar nerve displacement at the elbow in young baseball players

Abstract

Background Overhead‐throwing athletes are at risk of elbow injury because of valgus stress, leading to unstable ulnar nerves and neuropathy. Studies regarding ulnar nerve damage/displacement have been performed primarily in adults. Objective To determine the prevalence and related factors associated with ulnar nerve displacement at the elbow in young baseball players. Design Cross‐sectional study. Participants Youth baseball players ages 10–12 years were eligible to participate. Exclusion criteria were history of neuropathic pain, trauma, or prior surgery of the upper limb. Fifty‐seven participants were eligible for inclusion in the study. Main Outcome Measurements Demographic data and ultrasonography findings of ulnar nerve dynamics at the cubital tunnel were analyzed in a total of 114 elbows. Elbows were grouped into nondislocation and displacement (subluxation or dislocation) groups according to ultrasound findings. Logistic generalized estimating equations were used to identify factors associated with ulnar nerve displacement. Results Thirty‐six (31.6%) elbows demonstrated sonographic findings of ulnar nerve displacement, with 13 (11.4%) subluxations and 23 (20.2%) dislocations. Fourteen (24.6%) participants experienced nerve displacement in the dominant elbow only, whereas nerve displacement in both elbows occurred in 11 (19.3%) participants. Nerve displacement in the nondominant elbow only was not observed. Hand dominance and tenderness of the arcade of Struthersʼ were factors associated with ulnar nerve displacement (odds ratio, 2.81, and 9.73; 95% confidence interval, 1.34–5.91 and 2.45–38.68; p = .006 and .001, respectively). Conclusion One‐third of the young baseball players evaluated had ultrasonographic findings compatible with ulnar nerve displacement at the elbow. Hand dominance and tenderness of Struthers arcade were the only factors associated with ulnar nerve displacement. Ultrasound may help identify patients with ulnar nerve displacement and contribute to the understanding of its pathophysiology in young baseball players.

A review of upper extremity peripheral nerve injuries in throwing athletes

“…Diagnostic ultrasound is also very helpful to identify nerve displacement on dynamic imaging with elbow flexion. More recently, Kawabata and colleagues found ultrasound evidence of dynamic ulnar nerve displacement in one third of asymptomatic youth baseball players examined 96 . Diagnostic ultrasound is also helpful in identifying morphological nerve abnormalities, such as increases in nerve cross sectional area 30 .…”

“…More recently, Kawabata and colleagues found ultrasound evidence of dynamic ulnar nerve displacement in one third of asymptomatic youth baseball players examined. 96 Diagnostic ultrasound is also helpful in identifying morphological nerve abnormalities, such as increases in nerve cross sectional area. 30 MRI is not routinely used for the evaluation of ulnar neuropathy.…”

Snapping of the Upper Limb: a Clinical Overview

“…Dynamic ultrasound can reveal the snapping of the ulnar nerve during elbow movements (44). A recent study using dynamic ultrasound visualization identified a significant prevalence of ulnar nerve displacement in young baseball players, although some forms of nerve subluxation may also be observed in asymptomatic patients (45). In case of ulnar neuropathy, nerve conduction studies and electromyography (EMG) can assess nerve damage but are not useful to identify the underlying aetiology.…”

Proposed Musculoskeletal Examination of Youth and Adolescent Baseball Players

“…Imaging studies have been used to determine the effect of valgus torque on the medial elbow relative to ulnar nerve subluxation and neuropathy. While studies regarding ulnar nerve damage/displacement have been performed primarily in adults, a study by Kawabata et al (26) examined a group of 57 youth baseball players age 10 to 12 years, 31.6% identifying sonographic findings of ulnar nerve displacement correlating more commonly with the dominant hand and with tenderness to palpation of the arcade of Struther’s. With these findings in mind diagnostic ultrasound may be a valuable tool in identifying risk for injury in the throwing population.…”

“…A number of studies have looked at factors related to injury in the youth baseball population over the past year ranging in topics from; early sport specialization (ESS) (12)(13)(14)(15)(16), pitch counts (17)(18)(19)(20)(21)(22)(23), prethrowing protocols (24,25), imaging findings (26), to body region-specific inquiries (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43) in search for opportunities to reduce the risk of injury in this population. We will review a wide range of articles and their relevance to injury risk in this population.…”