Although limb differences in clinical indicators of posterior tightness exist in healthy overhead athletes, these measures appear to be influenced by humeral torsion rather than soft tissue tightness. Once torsion is accounted for, the limb differences observed clinically were minimal in healthy overhead athletes. When possible, accounting for humeral torsion when interpreting clinical measures of posterior shoulder tightness may aid in treatment decisions.

ACL injury and ACLR caused movement pattern alterations of the injured and uninjured leg that have previously shown to increase the risk for future non-contact ACL injury.

Background: Excessive trunk motion and deficits in neuromuscular control (NMC) of the lumbopelvic hip complex are risk factors for anterior cruciate ligament (ACL) injury. However, the relationship between trunk motion, NMC of the lumbopelvic hip complex, and triplanar knee loads during a sidestep cutting task has not been examined.Purpose: To determine if there is an association between multiplanar trunk motion, NMC of the lumbopelvic hip complex, and triplanar knee loads with ACL injury during a sidestep cutting task.Study Design: Descriptive laboratory study. Methods:The hip and knee biomechanics and trunk motion of 30 participants (15 male, 15 female) were analyzed during a sidestep cutting task using an optoelectric camera system interfaced to a force plate. Trunk and lower extremity biomechanics were calculated from the kinematic and ground-reaction force data during the first 50% of the stance time during the cutting task. Pearson product moment correlation coefficients were calculated between trunk and lower extremity biomechanics. Multiple linear regression analyses were carried out to determine the amount of variance in triplanar knee loading explained by trunk motion and hip moments.Results: A greater internal knee varus moment (mean, 0.11 6 0.12 NÁm/kg*m) was associated with less transverse-plane trunk rotation away from the stance limb (mean, 20.25°6 4.42°; r = 20.46, P = .011) and a greater internal hip adduction moment (mean, 0.33 6 0.25 NÁm/kg*m; r = 0.83, P \ .05). A greater internal knee external rotation moment (mean, 0.11 6 0.08 NÁm/ kg*m) was associated with a greater forward trunk flexion (mean, 7.62°6 5.28°; r = 0.42, P = .020) and a greater hip internal rotation moment (mean, 0.15 6 0.16 NÁm/kg*m; r = 0.59, P = .001). Trunk rotation and hip adduction moment explained 81% (P \ .05) of the variance in knee varus moment. Trunk flexion and hip internal rotation moment explained 48% (P \ .05) of the variance in knee external rotation moment. Conclusion:Limited trunk rotation displacement toward the new direction of travel and hip adduction moment are associated with an increased internal knee varus moment, while a combined increase in trunk flexion displacement and hip internal rotation moment is associated with a higher internal knee external rotation moment.Clinical Relevance: Prevention interventions for ACL injury should encourage trunk rotation toward the new direction of travel and limit excessive trunk flexion while adjusting frontal-and transverse-plane hip NMC.

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