Kazuya Seo

Prevalence and Clinical Characteristics of Osteochondritis Dissecans of the Humeral Capitellum Among Adolescent Baseball Players

Background: The prevalence and clinical characteristics of osteochondritis dissecans (OCD) of the humeral capitellum among adolescent baseball players are unknown. Purpose: To determine the OCD prevalence in adolescent competitive baseball players and to investigate the clinical characteristics of these patients. Study Design: Cross-sectional and case-control study; Level of evidence, 3. Methods: A total of 2433 baseball players (mean age, 14.5 ± 1.5 years) belonging to junior high school and high school baseball clubs were enrolled. Players completed a questionnaire, and the elbow of each player’s throwing arm was assessed by ultrasonography. Participants with abnormal results on ultrasonography were further examined through radiographic study. The OCD lesions were classified into stages based on radiographic results, and demographic data were compared between players with and without OCD lesions. Results: Osteochondritis dissecans of the humeral capitellum was found in 82 (3.4%) elbows by ultrasonography. Players with an OCD lesion began playing baseball at an earlier age (P = .016), had a longer duration of competitive play (P = .0013), and had experienced more present (P = .0025) and past (P < .0001) elbow pain compared with players without a lesion. There were no differences between the 2 groups in the position played (P = .26). Sixty-eight patients underwent further radiographic examination for OCD (radiography, computed tomography, magnetic resonance imaging). Of these players, 10 (14.7%) were classified as having stage I OCD (radiolucent stage); 26 (38.2%), stage II (fragmentation stage); 9 (13.2%), stage III (loose body stage); 9 (13.2%), stage IV (residual stage); and 14 (23.5%), stage V (postoperative stage). Conclusion: The prevalence of OCD of the humeral capitellum, including latent cases, was 3.4% among adolescent baseball players. Players with OCD lesions began playing baseball at earlier ages, had played for longer periods, and had experienced more elbow pain. The player’s current baseball position may not be related to the existence of OCD lesions in adolescents.

Whole-body and segmental muscle volume are associated with ball velocity in high school baseball pitchers

The aim of the study was to examine the relationship between pitching ball velocity and segmental (trunk, upper arm, forearm, upper leg, and lower leg) and whole-body muscle volume (MV) in high school baseball pitchers. Forty-seven male high school pitchers (40 right-handers and seven left-handers; age, 16.2 ± 0.7 years; stature, 173.6 ± 4.9 cm; mass, 65.0 ± 6.8 kg, years of baseball experience, 7.5 ± 1.8 years; maximum pitching ball velocity, 119.0 ± 9.0 km/hour) participated in the study. Segmental and whole-body MV were measured using segmental bioelectrical impedance analysis. Maximum ball velocity was measured with a sports radar gun. The MV of the dominant arm was significantly larger than the MV of the non-dominant arm (P < 0.001). There was no difference in MV between the dominant and non-dominant legs. Whole-body MV was significantly correlated with ball velocity (r = 0.412, P < 0.01). Trunk MV was not correlated with ball velocity, but the MV for both lower legs, and the dominant upper leg, upper arm, and forearm were significantly correlated with ball velocity (P < 0.05). The results were not affected by age or years of baseball experience. Whole-body and segmental MV are associated with ball velocity in high school baseball pitchers. However, the contribution of the muscle mass on pitching ball velocity is limited, thus other fundamental factors (ie, pitching skill) are also important.

The laterality of physical function in high school baseball players with shoulder or elbow injury: Comparison of laterality with positive group and negative group.

[Purpose] The purpose of this study was to investigate the laterality of flexibility and muscle strength in high school baseball players with shoulder or elbow injury. [Methods] Subjects were 76 high school baseball players participated in the medical check in Kyoto. Measurement outcomes were judgment of elbow and shoulder injury, range of motion, and muscle strength. Laterality of flexibility and muscle strength was calculated by subtracting non-throwing side from throwing side. Student T-test was used to analyze difference positive and negative group with each injury. The significance level was set at 5%. [Results] Laterality of shoulder internal rotation angle in positive group with shoulder injury was lower compared to negative group (p<0.05). Laterality of shoulder external rotation angle in positive group with elbow injury was lower compared to negative group (p <0.05). [Conclusion] It was suggested that the analysis of laterality in shoulder rotation angle might be helpful to predict shoulder or elbow injury in high school baseball players.