Hip internal and external rotation range of motion reliability in youth baseball players

BACKGROUND: Impaired hip range of motion has been related to increased injury risk in baseball players. However, no hip rotation range of motion (ROM) reliability studies have been performed in youth, which cannot be assumed to be comparable to adults. This study aimed to: 1) assess the inter- and intro-rater reliability of hip rotation passive ROM in youth baseball players; 2) calculate the standard error of measurement (SEM) and minimum clinically important difference (MCID). METHODS: Hip external (ER) and internal (IR) rotation were measured. Inter and intra-rater reliability were assessed through intraclass correlation coefficients (ICC) and 95% Confidence interval (95% CI), with SEM and MCID. Bland-Altman plots were used to assess overall measurement bias. RESULTS: Nineteen youth baseball players participated. Hip ER intra-rater ICC was excellent (tester one: 0.983 (0.965, 0.993); tester two: 0.952 (0.903, 0.980) and hip IR was excellent (tester one: 0.965 (0.927, 0.985); tester two: 0.965 (95%CI: 0.928, 0.985). Hip ER SEM was 3.2 degrees, and hip IR was 22 degrees. Hip ER MCID was 7.5 degrees, and hip IR was 5.1 degrees. Bland-Altman plots for hip ER and IR did not detect any bias. CONCLUSIONS: Hip ROM inter-rater and intra-rater reliability was excellent for use in youth baseball players, with no rater bias. Sports medicine professionals can reliably assess supine hip rotation ROM in youth baseball players. This ROM methodology can be easily administered within the clinic or pitch-side, and interpret the results, increasing its real-world applicability.