Elbow Ulnar Collateral Ligament Injuries in the Female Athlete

Introduction

While there is abundant literature on ulnar collateral ligament (UCL) injuries in male athletes, predominantly professional baseball players, research remains sparse on the pathoanatomy, epidemiology, treatment, and outcomes of UCL injuries in female athletes. A literature review by Gardner and Bedi demonstrated that only 79 of 1902 (4.15%) patients within UCL studies are female. The majority of elbow UCL studies consist of either small case reports or limited case series or otherwise involve larger studies where a predominant cohort of the athletes are male. A small subset of these larger studies includes female athletes; however, many of the studies do not separate out the female athlete when specifically discussing outcomes.

Several recent studies have highlighted gender-related differences in orthopedic conditions; however, there remains a paucity of literature on outcomes following the treatment of UCL injuries in female athletes. The majority of studies on elbow UCL injuries focus on professional baseball pitchers. Baseball is a sport dominated by male athletes, whereas softball is dominated by female athletes. Softball pitchers have a significantly different throwing pattern (underhand/windmill) than baseball pitchers (overhand), which may protect them from UCL injuries.

Electromyographic study of the windmill pitch demonstrates that the highest level of biceps eccentric contraction occurs at the 9 o'clock position, just prior to ball release when the shoulder is experiencing maximum distraction stress and the elbow is experiencing maximum extension torque. Peak biceps motor activation was significantly higher than that during an overhand throwing motion where the biceps is responsible for providing elbow flexion torque. Alteration of peak forces with the elbow flexed (overhand) versus extended (underhand/windmill) may be related to the incidence of UCL injury. When standard overhand throwing kinematics and kinetics are compared between genders, females were found to have lower ball velocity, lower elbow extension angular velocity, lower proximal forces on the elbow and shoulder joints, lower pelvis and upper torso rotation, and shorter stride length. Notably, in this study, these reductions were not compared to the overall athlete stature or body muscle composition, but rather were compared as absolute values.

Gymnastics represents a more female-dominated sport (compared with male athlete participation). Elbow UCL injuries tend to occur from the overhead, weight-bearing/compression, and the rotational forces on the upper extremity caused by the unique movements of the sport. Therefore gymnasts represent a large proportion of female athletes with UCL injuries. Floor exercises followed by balance beam have been shown to have the highest rates of acute injuries, with bars and vault having lower injury rates. Large lateral compression and valgus forces have been noted during the double-arm support phase of a backhand spring (a maneuver performed on both floor and balance beam), which may explain the pathogenesis of lateral capitellar osteochondritis dissecans (OCD) and UCL injuries during this maneuver.