Sammendrag
Background: Describing normal knee kinematics and gender differences is of great importance to not only better understand knee mechanics and pathomechanics, but also to set important aspects of training and rehabilitation protocols. Finite Helical Axis (FHA) measures of the knee joint simultaneous rotations and translations during different exercises could capture specifics of knee kinematics in different population groups.
Aim: The aim of this study was to investigate knee kinematics during different open-chain and closed-chain exercises using a Finite Helical Axis approach, and to examine differences between males and females.
Study design: Cross-sectional study
Methods: 20 healthy, sport active participants (mean±SD; age 25.10±2.02 years; height, 175.17±11.49 cm; weight, 73.26±11.97) were divided into male (n=10) and female (n=10) groups. Each group performed Bilateral squat, Standing leg flexion and Seated leg extension. Movement was registered with an optical motion capture system. Two outcome variables have been investigated: Medio-Lateral FHA inclination and Antero-Posterior FHA translation direction during stepwise knee flexion intervals of ∼15°. Multi-level repeated measures analysis of variance (ANOVA) was performed to compare changes between groups.
Results: No significant differences were found between gender groups in all three exercises (F4,15=0.281; p=886, ƞ2=0.07). Overall significant differences were documented in Medio-Lateral inclination and FHA Antero-Posterior translation between all three exercises (F8,68=52.4; p<0.001, ƞ2=0.86). Bilateral squat displayed the smallest amount of Antero-Posterior FHA translation, while in Standing leg flexion, translation was the most noticeable in posterior direction. Medio-Lateral FHA inclination was found to be the least in Standing leg flexion in both internal and external direction but did not differ between Bilateral squat and Seated leg extension.
Conclusion: This study demonstrated that that knee joint exhibits different kinematic patterns between closed-chain and open-chain loading conditions and not between males and females. Observed overall differences account for different muscle activity and joint articulation. Our findings document important exercise differences and set implications for their use at different timepoints in rehabilitation or training protocol after a knee injury.