ABSTRACT
Background: The relationship between lower mobility, as measured by the elbow forward translation motion (T-motion) test, a new indicator of shoulder joint complex movement that measures elbow position when both dorsal hands are placed on the iliac crest while in a sitting position, and the parameters calculated by ultrasonography is unknown. The purpose of this study was to investigate the limiting factors of T-motion through motion analysis of the humeral head and rotator cuff muscles using ultrasonography in college baseball players. Methods: Thirteen college baseball players participated in this cross-sectional study. The shortest distance from the posterior edge of the glenoid to the humeral head was measured in the static and T-motion positions, and the difference was calculated as the humeral head translation. The velocity of the infraspinatus was calculated during shoulder internal/external rotation using the particle image velocimetry method. These parameters were compared between the throwing and nonthrowing sides to examine the limiting factors of T-motion. Results: This study indicated moderate-to-good reliability for the parameters calculated by ultrasonography. The mean anterior translation distance was significantly greater on the throwing side than on the nonthrowing side (r = 0.56, P = .015). The mean velocity of infraspinatus during internal rotation was significantly lower on the throwing side than on the nonthrowing side (r = 0.51, P = .028). Conclusion: Increased anterior translation of the humeral head and decreased the velocity of infraspinatus are likely correlated with reduced T-motion mobility in college baseball players. These methods showed potential for physical therapy assessment and intervention to prevent shoulder dysfunction.
ABSTRACT
Background: Range of motion (ROM) limitations can result in restricted activities of daily living (ADL) due to shoulder dysfunction, suggesting that evaluation of complex shoulder movements is necessary in clinical practice. Here, we present a new physical examination, the elbow forward translation motion (T-motion) test for measuring the position of the elbow when both dorsal hands are placed on the iliac crest in a sitting position and the elbow is moving forward. We examined the relationships between T-motion and shoulder function to identify the significance of this test in clinical practice. Methods: Preoperative patients with rotator cuff tears (RCTs) were eligible for this cross-sectional study. Active ROM and Japanese Orthopaedic Association (JOA) scores were measured as shoulder function. The degree of internal rotation was based on the Constant-Murley Score. We defined a positive T-motion test result as an elbow positioned posterior to the body on the sagittal plane. Group comparisons and logistic regression analyses were conducted to investigate the relationships between the availability of T-motion and shoulder function. Results: Sixty-six patients with RCTs participated in this cross-sectional study. The values of the JOA total score (P < .001), subscale of function and ADL (P < .001), active range of forward flexion (P = .006), abduction (P < .001), and external rotation (P < .001) were lower in the positive group than in the negative group. In addition, a significant correlation was found between the availability of T-motion and internal rotation by the chi-square test (P < .001). Logistic regression analyses showed that internal rotation (odds ratio 2.69; 95% confidence interval 1.47-4.93; P < .01) and external rotation (odds ratio 1.07; 95% confidence interval 1.00-1.14; P = .04) were related to the availability of T-motion after adjustments for covariates, and the cutoff points were 4 points for internal rotation (area under the curve 0.833, sensitivity 53.3%, specificity 86.1%, P < .001) and 35° for external rotation (area under the curve 0.788, sensitivity 60.0%, specificity 88.9%, P < .001). Conclusion: The positive T-motion group exhibited low shoulder function, including a less active ROM and JOA shoulder score. T-motion, which is a quick and simple movement, may be a new indicator for a complex shoulder motion and contribute to evaluating the decreased ADL and limited shoulder motion in patients with RCTs.