Risk factors for elbow injuries in professional baseball players based on ultrasound images: a prospective cohort study of 56 players

Background

Risk factors for the development of elbow injuries, focusing on the function of the flexor digitorum superficialis (FDS) and the structure of the ulnar nerve, have not been fully clarified. This study aimed to prospectively investigate the ring-down artifact (RDA) under gravity load and gravity load with FDS contraction conditions and the cross-sectional area (CSA) of the ulnar nerve and clarify the risk factors for elbow injuries in professional baseball players.

Methods

We enrolled 56 professional Japanese baseball players without elbow pain. The measurements were RDA under gravity load and gravity load with FDS contraction, and the CSA of the ulnar nerve at the Struthers arcade, cubital tunnel, and Osborne's ligament. We prospectively investigated the development of elbow injuries over a 1-year period. Statistical analysis was performed using Fisher's exact test, and the relative risk (RR) was calculated.

Results

The development of elbow injuries was associated with the following variables: the presence of RDA under gravity load (P < .01, RR: 5.22), the presence of RDA under gravity load with FDS contraction (P = .02, RR: 3.26), CSA at Struthers arcade ≥10 mm² (P < .01, RR: 6.71), CSA at cubital tunnel ≥10 mm² (P < .01, RR: 36.56), and CSA at Osborne's ligament ≥10 mm² (P < .01, RR: 4.57).

Conclusion

The RDA under gravity load, FDS contraction conditions, and increased CSA of the ulnar nerve were associated with the development of elbow injuries in professional baseball players.