Hip function and lower extremity kinematics during pitching motion are associated with medial elbow injury: A prospective cohort study of preadolescent baseball pitchers

Abstract

We conducted a prospective cohort study to identify the risk factors of medial elbow injury in preadolescent baseball pitchers. Seventy-three male baseball pitchers (9-11 years old) participated in this study, and we measured their hip function and pitching motion. For hip function, range of motion (ROM; external rotation, internal rotation, and total range) and muscle strength (external rotation, internal rotation, abduction, and adduction) were assessed. Pitching motion was measured using three-dimensional motion analysis and force plates. Kinematics of the lower extremities was calculated from foot contact to ball release. After these measurements, the participants were followed up every 4 months for 1 year with clinical and ultrasonographic assessments of medial elbow injury. We compared the values obtained from the injury group with those obtained from the non-injury group using t-test and examined clinically important factors related to injuries with multivariate logistic regression analysis. Eleven players were excluded and one player dropped out of the study, leaving 61 pitchers who completed the follow-up and were analyzed. Eighteen players (29.5%) reported medial elbow injuries. The multivariate logistic regression model revealed that ROM of knee valgus at foot contact in the drive leg in pitching motion (odds ratio [OR]＝0.901; 95% confidence interval [CI], 0.816-0.995; p＝0.039) is associated with the development of medial elbow injury. In particular, dysfunction of the drive leg may cause such malfunctions as early rotation of the trunk. T83he results of this study demonstrate the importance of evaluating and training the drive leg in preadolescent baseball pitchers to prevent medial elbow injury.