ANTHROPOMETRIC MEASUREMENTS AS PREDICTORS OF THE DEGREE OF CARRYING ANGLE IN COLLEGE BASEBALL PLAYERS By CHRIS COX Bachelor of Arts/Science in Secondary Education (original) (raw)
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The American journal of sports medicine, 2014
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Journal of Anatomy, 2012
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American Journal of Sports Medicine, 2018
Background: Scapular dyskinesis among throwers is thought to affect kinetic chain function and increase the load demands on the shoulder and/or elbow. However, the biomechanical relationship between scapular orientation and elbow valgus load, which is associated with ulnar collateral ligament (UCL) injury, has not been determined. Purpose: To evaluate the effect of increased scapular internal rotation (IR) and glenohumeral external rotation (GHER) on elbow valgus load in a static simulation of the late cocking phase of throwing. Study Design: Controlled laboratory study. Methods: Seven fresh-frozen male cadaveric upper extremities were used with a custom testing system to simulate the late cocking phase. First, the authors evaluated the effect of increasing scapular IR on maximum GHER and forearm angle (forearm axis relative to the ground). Each parameter was evaluated at 20°to 40°(5°increments) of scapular IR by applying 2.2-NÁm external rotation torque to the humerus and 0.75-NÁm valgus torque to the forearm. Next, to evaluate elbow valgus stability, the humerus was locked in maximal GHER at 40°of scapular IR, and sequentially increasing torque (0.75-7.5 NÁm by 0.75-NÁm increments) was applied to the forearm. Valgus angle and joint gap were evaluated at each torque. Results: Increases in scapular IR !5°significantly decreased GHER (P \ .01). With increasing valgus torque, forearm angle also increased linearly (R 2 = 0.85, P \ .001). To compensate for the GHER deficit at 40°of scapular IR, a linear regression model showed that 25.3 NÁm of valgus torque would be necessary to reach the original forearm position. In the intact condition, applying elbow valgus torque !5.25 NÁm significantly increased valgus angle and the joint gap (P \ .01). Conclusion: Increased scapular IR significantly decreased GHER. Compensation for the GHER deficit significantly increased the elbow valgus load required to reach the same forearm position. Clinical Relevance: Increased scapular IR may increase the risk of elbow UCL injury among throwing athletes.
Muscle contribution to elbow joint valgus stability
Journal of Shoulder and Elbow Surgery, 2007
Repetitive valgus stress of the elbow can result in excessive strain or rupture of the native medial ulnar collateral ligament (MUCL). The flexor-pronator mass (FPM) may be particularly important for elbow valgus stability in overhead-throwing athletes. The aim of this study was to identify the relative contribution of each muscle of the FPM-that is, the flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), and pronator teres (PT)-and of the extensorsupinator mass, including the extensor carpi ulnaris (ECU), extensor digitorum communis (EDC), extensor carpi radialis longus and brevus, and brachioradialis, to elbow valgus stability at 45 and 90 of elbow flexion angles. Eight fresh-frozen elbow specimens (mean age at death, 73.75 6 14.07 years) were tested. With the skin and subcutaneous tissue removed but all muscles left intact, each individual muscle of the FPM and extensorsupinator mass was loaded at 3 levels of force. During loading, strain on the MUCL and the kinematics of the elbow were measured simultaneously. Kinematic measurements were later repeated when the MUCL was fully cut. At 45 and 90 of elbow flexion, individual loading of the FCU, FDS, and FCR caused significant relief to the MUCL whereas the PT produced no significant change. Furthermore, of these flexor muscles, the FCU provided the greatest MUCL relief at both 45 and 90 . In contrast, loading of the ECU at 45 of elbow flexion produced a significant increase in MUCL strain. All FPM muscles caused significant elbow varus movement at both 45 and 90 when loaded individually. At 90 , the FCU created more motion than both the FCR and PT but not the FDS, and the FDS created more motion than the PT. The EDC and ECU created