Evaluating Changes in Shear Modulus of Elbow Ulnar Collateral Ligament in Overhead Throwing Athletes Over the Course of a Competitive Season

Abstract

The anterior band of the ulnar collateral ligament (UCL) is commonly subjected to repetitive stress in overhead-throwing athletes, causing high subfailure strain and change in mechanical properties of the ligament. Understanding the change in UCL mechanical properties after repetitive loading can help to evaluate the health status of UCL. The objective of this study was to evaluate changes in UCL shear modulus in overhead-throwing, Division I college-level athletes over the course of a competitive season using ultrasound shear wave elastography (SWE). The proposed protocol quantified changes in shear modulus of UCL in 17 baseball players at preseason and season-end time points as well as in five football quarterbacks at preseason, midseason, and season-end time points. The highest shear modulus values were obtained in the nondominant arm at preseason time points in both groups of athletes. The average UCL shear modulus at the season-end decreased by 39.35% and 37.96% compared to the preseason values in dominant and nondominant arms, respectively. This study shows that SWE could quantify changes in the shear modulus of the UCL after repetitive loading, suggesting that it could be a useful clinical tool for evaluating the risk of UCL injury. Further research on injured overhead-throwing athletes is warranted.