Relationship between shoulder and elbow range of motion and ultrasonographic structural abnormalities in the elbow of Taiwanese high school baseball players

BACKGROUND: Ultrasonographic structural abnormalities are regarded as one of the risk factors of elbow injuries. Elbow injuries are commonly associated with decreased shoulder/elbow range of motion (ROM). The purpose of this study is to determine the relationship between shoulder/elbow ROM and elbow ultrasonographic structural abnormalities in Taiwan high school baseball players.

METHODS: A total of 533 Taiwan high school baseball players were enrolled. Physical examinations including measurements on shoulder/elbow ROM and elbow sonographic examinations were performed and recorded by professional physicians. The analyses were conducted in three subgroups according to their defensive position because the training programs were different. All players pooled, pitchers-only, and fielders-only, due to several demographic differences among these subgroups. In all the subgroups, univariate analyses were conducted separately for participants with and those without elbow ultrasonographic structural abnormalities, and then multivariate analyses were conducted to identify factors significantly related. The odds ratios (ORs) were used to estimate the risk of elbow ultrasonographic structural abnormalities.

RESULTS: Demographic data showed that pitchers had taller body height (P < 0.001) and greater elbow flexion/extension ROM (P < 0.001). When all players were pooled, significant risk factors included started playing baseball at an younger age (OR = 1.202; 95% CI = 1.064-1.357; P = 0.003), longer experience of official baseball (OR = 1.154; 95% CI = 1.038-1.283; P = 0.008), lower total shoulder rotation angle (OR = 1.007; 95% CI = 1.000-1.014; P = 0.050), and less total elbow arm angle (OR = 1.052; 95% CI = 1.017-1.088; P = 0.003) For pitchers, significant risk factors included longer experience of official baseball (OR = 1.342; 95% CI = 1.098-1.640; P = 0.004), lower total shoulder rotation angle (OR = 1.016; 95% CI = 1.004-1.027; P = 0.006), and lower total elbow arm angle (OR = 1.075; 95% CI = 1.024-1.129; P = 0.004) (Table 5). There were no significant risk factors for elbow structural abnormalities in fielders.

CONCLUSION: For Taiwan high school pitchers, longer official baseball experience, decreased shoulder total rotational angle, and decreased elbow total flexion/extension angle, were related to ultrasonographic structural abnormalities in elbows.