Hello, thank you for taking the time to listen to our presentation. I'm Drew Hagen. And I'm Toby Addis. And we are second year osteopathic medical students from the Edward Valley College of Osteopathic Medicine, Virginia campus. And we will be presenting our research on forearm flexor strength as a predictive risk factor for ulnar collateral ligament injury in baseball athletes, conducted in association with VCOM Sports and Osteopathic Medicine and the Baton Rouge Orthopedic Clinic. The primary objective of this study was to determine if an association exists between forearm flexor muscle imbalance and medial elbow injury in baseball pitchers. Medial elbow injuries, especially that of the ulnar collateral ligament, are highly prevalent among baseball pitchers and can have significant impacts on playability and associated costs of recovery from those injuries. The injuries themselves can be attributed to the large external valgus torque experienced by the medial elbow during maximal external rotation. The intrinsic muscles that protect the UCL that were investigated in this study include the flexor digitorum superficialis, the flexor digitorum profundus, and the flexor carpi ulnaris, which can be visualized in the center image. Previous studies have demonstrated that these muscles can compensate the large external valgus torque imposed on the medial elbow during pitching. Limited research in the past has examined the potential contribution of muscle strength imbalance towards the mechanisms of medial elbow injury in baseball pitchers, prompting us to conduct this study. Our research was conducted as a retrospective cohort study of data from baseball pitchers utilizing the FlexProGrip device. Inclusion criteria for our study included baseball pitchers with medial elbow injuries and baseball pitchers without medial elbow injuries. The exclusion criteria were all other positional players on the baseball team. The specific data that we collected included force measurement for flexion at the fingertip, force measurement of the midfinger flexion, and then the ratio of those two respective force measurements. Those measurements were specifically selected in consideration of the osteopathic concept of the interrelationship of the structure and function of the neuromusculoskeletal system. These measurements were accurately obtained utilizing the FlexProGrip device, which can be seen in the figure at the bottom left of the slide. The participants were then divided into two cohorts, pitchers with medial elbow injury or pain, possibly from a strain, a sprain, tear, recent surgical repair, or adjacent joint pain, and then pitchers with no such medial elbow injury or pain that required rest from throwing. Those individuals were then de-identified in the sample pool, and a statistical analysis was performed utilizing RStudio, and the two-sample Mann-Whitney U, also known as the Wilcoxon Rank Sum Test, was selected for robustness for smaller sample sizes. Utilizing RStudio, the Mann-Whitney U test was performed across the injured and uninjured cohorts of the forefinger-fingertip flexion measurements, the forefinger-midfinger flexion measurements, and the midfinger-to-fingertip flexion ratio measurements. The chart in the middle of the slide shows that our analysis revealed significant p-values for the forefinger-midfinger flexion measurements and the midfinger-to-fingertip flexion ratio measurements, with p-values that were less than a ten-thousandth. Significant p-values were found for the forefinger-fingertip flexion measurements with a p-value of 0.4507. Therefore, we were able to statistically determine that a significant difference exists between the forefinger-midfinger flexion measurement and the ratio of midfinger flexion strength to fingertip flexion strength of the injured and uninjured cohorts. From the results and the statistical analysis, we were able to demonstrate that a measurable correlation between midfinger flexion strength and throwing-associated injuries in baseball pitchers exists. A potential underlying mechanism that may explain this phenomenon is that the relatively lower midfinger flexion strength in the injured cohort indicates that the flexor digitorum superficialis muscle is not able to provide as much muscular support to the humeral ulnar joint and therefore places a much higher strain on the ulnar collateral ligament, thus leading to injury. This mechanism is also supported by the findings from EKZU and their contributors, where their study demonstrated that 89% of participants with combined ulnar collateral ligament and flexor pronator muscle injury had identifiable flexor digitorum superficialis muscle injury. In regards to further research, future investigators should aim to include larger samples in addition to investigating the relationship between ulnar collateral ligament injury and the strength of other myotendinous units crossing the humeral ulnar joint, such as the pronator teres muscle and the flexor carpi radialis muscle, in addition to others. On top of that, investigations of the protected benefit of targeted strength-building exercise of forearm flexors should be performed to reduce the burden of U-cell injury in this population. Finally, the authors and contributors of this project would like to extend our thanks and acknowledge FlexProGrip for collecting and providing the de-identified data for our study. Thank you.

UCL injuries

forearm flexor strength

baseball pitchers

FlexProGrip device

muscle strength imbalance