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Background: A smaller knee flexion angle and larger knee valgus angle during weight-bearing activities have been identified as risk factors for non-contact anterior cruciate ligament (ACL) injuries. To prevent such injuries, attention has been focused on the role of hip strength in knee motion control. However, gender differences in the relationship between hip strength and knee kinematics during weight-bearing activities in the frontal plane have not been evaluated. Hypothesis/Purpose: The purpose of this study was to determine the influence of hip strength on knee kinematics in both genders during a single-legged landing task in the frontal plane. The hypotheses were that 1) subjects with a greater hip strength would demonstrate larger knee flexion and smaller knee valgus and internal rotation angles and 2) no gender differences would exist during the single-legged landing task. Methods: Forty-three Japanese collegiate basketball players (20 males, 23 females) participated in this study. Three-dimensional motion analysis was used to evaluate knee kinematics during a single-legged medial drop landing (SML). A hand-held dynamometer was used to assess hip extensor (HEXT), abductor (HAB), and external rotator (in two positions: seated position [SHER] and prone [PHER]) isometric strength. Spearman rank correlation coefficients (ρ) were determined for correlations between hip strength and knee kinematics at initial contact (IC) and peak (PK) during SML (p < 0.05). Results: Negative correlations were observed between the knee valgus angle at IC and HEXT (ρ = -0.48, p = 0.02), HAB (ρ = -0.46, p = 0.03) and PHER (ρ = -0.44, p = 0.04) strength in females. In addition, a significant positive correlation was observed between the knee flexion angle at PK and HEXT strength (ρ = 0.61, p = 0.004) in males. Conclusions: Significant correlations between hip strength and knee kinematics during SML were observed in both genders. Hip strength may, therefore, play an important role in knee motion control during sports activities, suggesting that increased hip strength may help to prevent non-contact ACL injuries in athletes of both genders. Moreover, gender-specific programs maybe needed to control abnormal knee motion, as the influence of hip strength on knee kinematics may differ based on gender. [ABSTRACT FROM AUTHOR]

Background:A disadvantage of pivot-shift maneuvers is that the examiner has to subjectively evaluate the degree of pivot shift observed. It is unknown whether the various maneuvers are biomechanically identical.Purpose:To compare biomechanical features of 3 clinical maneuvers for the anterior cruciate ligament (ACL)–deficient knee: the pivot-shift test, the jerk test, and the N-test.Study Design:Controlled laboratory study.Methods:A total of 28 patients with an isolated ACL injury were examined by use of 3 pivot-shift maneuvers (pivot-shift test, jerk test, and N-test). An electromagnetic sensor system was used to evaluate the 3-dimensional knee kinematics of each patient’s injured and uninjured knees during each maneuver. Peak coupled anterior tibial translation (pCAT) and maximal acceleration of posterior translation (APT) were measured relative to results during a flexion-extension motion in each test.Results:The pCAT of the pivot-shift test was significantly greater than that of both the jerk test and the N-test (P = .0020 and P < .0001, respectively); there was no statistical difference in pCAT between the jerk test and the N-test. The APT of the N-test was significantly greater than that of both the pivot-shift test and the jerk test (P < .0001), while there was no statistical difference between the pivot-shift and the jerk tests. There was no correlation between pCAT and APT in each test.Conclusion:The pivot-shift test, jerk test, and N-test have different biomechanical characteristics to induce the pivot-shift phenomenon in the ACL-deficient knee. The pivot-shift test produced the largest side-to-side difference in pCAT, whereas the N-test provoked the largest side-to-side difference in APT.Clinical Relevance:The biomechanical differences in pivot-shift maneuvers are caused by technical differences, and clinicians should understand these biomechanical differences while practicing the maneuvers. The electromagnetic sensor system is clinically useful for quantifying the pivot-shift phenomenon. [ABSTRACT FROM AUTHOR]