What question did this study set out to answer?

The study aimed to investigate the relationship between carrying angle and the severity of ulnar nerve instability in baseball pitchers.

March 23, 2026JSES Reviews Reports and Techniques0 citationsOpen Access

Is the degree of carrying angle associated with ulnar nerve instability? A cross-sectional study of high school baseball pitchers

YHYuhei HatoriGunma University TTTsuyoshi TajikaGunma University HSHitoshi ShitaraGunma University

Key Points

The study aimed to investigate the relationship between carrying angle and the severity of ulnar nerve instability in baseball pitchers.
Conducted a cross-sectional study with 106 high school baseball pitchers.
Utilized ultrasound examinations to assess ulnar nerve instability and elbow joint integrity.
Classified participants into three groups based on UNI severity: no instability, subluxation, and dislocation.
The distribution of ulnar nerve instability types was similar on both throwing and non-throwing sides.
No significant differences were found in carrying angle among the different UNI groups.
No correlation was observed between carrying angle and ulnar collateral ligament laxity or other clinical findings.

Abstract

BackgroundAn increased carrying angle on the throwing side has been observed in professional pitchers.Elbow alignment is known to be a factor in the strain stress on the ulnar nerve.Ulnar nerve instability (UNI), in which the nerve snaps forward over the medial epicondyle during elbow flexion, is reportedly more common in pitchers than in other players.However, no studies have examined the association between elbow alignment and UNI severity in baseball players.This study assessed the correlation between the carrying angle (CA) and UNI severity in high school baseball pitchers. MethodsA total of 106 high school baseball pitchers who underwent medical checkups during the offseason in 2023 were examined.Ultrasound examinations were conducted to assess the presence or absence of UNI and medial joint space under rest and gravity stress on both sides of the elbow.The participants were divided into three groups based on the ultrasonographic findings of UNI: no instability (type N), subluxation (type S), and dislocation (type D).Clinical and physical examinations were performed, which included measurement of CA, grip strength, key pinch strength, and a check for ulnar nerve symptoms bilaterally. ResultsThe distribution of UNI types on the throwing side was 37%, 31%, and 32% for types N, S, and D, respectively.A similar distribution was found on the non-throwing side: 36% for Type N, 32% for Type S, and 32% for Type D. Overall, there was no statistically significant difference in the prevalence of these types between the two sides.The carrying angle of the throwing arm did not differ significantly between the three UNI groups: Type N (13.6 0.4), Type S (12.7 0.3), and Type D (12.0 0.3) (p=0.25).On the throwing side, the different UNI types did not show significant differences in the degree of ulnar collateral ligament (UCL) laxity or in other clinical and physical findings. J o u r n a l P r e -p r o o f ConclusionThis study found no significant difference in bony alignment, as indicated by the carrying angle, between the degrees of UNI among high school baseball pitchers.When categorized by UNI type, no significant differences were observed in the throwing side with respect to UCL laxity or other clinical and physical findings.

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