HYPOTHESIS: There are some risk factors that could predispose a young baseball player to elbow injuries. MATERIALS AND METHODS: Study participants were 294 baseball players aged 9 to 12 years old. A questionnaire, physical examination, and ultrasound imaging to investigate elbow injuries were performed. Data for the groups with and without elbow injuries were analyzed statistically using multivariate logistic regression models. RESULTS: Ultrasound imaging showed that 60 participants had elbow injuries, including medial epicondylar fragmentation in 58 and osteochondritis dissecans of the capitellum in 2. The odds ratio (95% confidence interval) of the risk factors that statistical analysis showed were significant were age older than 11 years, 2.82 (1.30-6.10); height exceeding 150 cm, 2.02 (1.07-3.82); pitching, 4.50 (2.42-8.37); daily training, 1.96 (1.02-3.79); range of motion (ROM) of external rotation of the shoulder below 130 degrees , 1.98 (1.01-3.87); muscle strength (MS) of external rotation of the shoulder exceeding 80 N, 4.11 (1.47-11.55); and MS of internal rotation of the shoulder exceeding 100 N, 2.04 (1.08-3.90). DISCUSSION: Risk factors for elbow injuries are age, height, pitcher, days of training, grip strength, range of motion of external rotation of the shoulder, and muscle strength of the shoulder. CONCLUSION: As new information, our results suggest that decrease of ROM of external rotation of the shoulder and increase of MS of external and internal rotation of the shoulder predispose elbow injuries. Copyright 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.
HYPOTHESIS: There are some risk factors that could predispose a young baseball player to elbow injuries. MATERIALS AND METHODS: Study participants were 294 baseball players aged 9 to 12 years old. A questionnaire, physical examination, and ultrasound imaging to investigate elbow injuries were performed. Data for the groups with and without elbow injuries were analyzed statistically using multivariate logistic regression models. RESULTS: Ultrasound imaging showed that 60 participants had elbow injuries, including medial epicondylar fragmentation in 58 and osteochondritis dissecans of the capitellum in 2. The odds ratio (95% confidence interval) of the risk factors that statistical analysis showed were significant were age older than 11 years, 2.82 (1.30-6.10); height exceeding 150 cm, 2.02 (1.07-3.82); pitching, 4.50 (2.42-8.37); daily training, 1.96 (1.02-3.79); range of motion (ROM) of external rotation of the shoulder below 130 degrees , 1.98 (1.01-3.87); muscle strength (MS) of external rotation of the shoulder exceeding 80 N, 4.11 (1.47-11.55); and MS of internal rotation of the shoulder exceeding 100 N, 2.04 (1.08-3.90). DISCUSSION: Risk factors for elbow injuries are age, height, pitcher, days of training, grip strength, range of motion of external rotation of the shoulder, and muscle strength of the shoulder. CONCLUSION: As new information, our results suggest that decrease of ROM of external rotation of the shoulder and increase of MS of external and internal rotation of the shoulder predispose elbow injuries. Copyright 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.