Frontal Knee Kinematics Research Articles

A Musculoskeletal Model Customized for Sagittal and Frontal Knee Kinematics With Improved Knee Joint Stability.

Current lower limb musculoskeletal (MSK) models focus on sagittal plane kinematics. However, abnormal gait is typically associated with sagittal plane motions crossing into other planes, limiting the use of current MSK models. The purpose of this study was twofold, first, to extend the capability of a full-body MSK model from the literature to include frontal knee plane kinematics during healthy gait, and second, to propose and implement a realistic muscle discretization technique. Two MSK model constructs were derived-the first construct (Knee2_SM) allowed two degrees-of-freedom (sagittal and coronal) at the knee and the second construct (Knee2_MM) implemented multiline elements for all the lower limb muscles in conjunction with two knee degrees-of-freedom. Motion analysis data of normal gait cycle from 10 healthy adults were used to compare joint kinematics, muscle moment arms, muscle forces, and muscle activations, between new constructs and the original model. Knee varus-valgus trajectories were estimated with the mean peak values ranging from 9.49 deg valgus to 1.57 deg varus. Knee2_MM predicted a significant difference (p < 0.05) in moment arms and forces in those muscles responsible for medial-lateral stability of the knee. The simulated muscle activations generated by the Knee2_MM model matched more closely to the experimental electromyography (EMG) when qualitatively compared. This study enhances the capability of the sagittal plane full-body MSK model to incorporate knee varus-valgus motion while keeping the joint stability intact and improving muscle prediction.

Knee kinematics is altered post-fatigue while performing a crossover task

To examine the effect of a sequential fatigue protocol on lower extremity biomechanics during a crossover cutting task in female soccer players. Eighteen female collegiate soccer players alternated between a fatigue protocol and two consecutive unanticipated crossover trials until fatigue was reached. Lower extremity biomechanics were evaluated during the crossover using a 3D motion capture system and two force plates. Repeated-measures ANOVAs analysed differences between three sequential stages of fatigue (pre, 50, 100%) for each dependent variable (α = 0.05). Knee flexion angles at initial contact (IC) for pre (-32 ± 9°) and 50% (-29 ± 11°) were significantly higher than at 100% fatigue (-22 ± 9°) (p < 0.001 and p = 0.015, respectively). Knee adduction angles at IC for pre (9 ± 5°) and 50% (8 ± 4°) were significantly higher (p = 0.006 and p = 0.049, respectively) than at 100% fatigue (6 ± 4°). Fatigue altered sagittal and frontal knee kinematics after 50% fatigue whereupon participants had diminished knee control at initial contact. Interventions should attempt to reduce the negative effects of fatigue on lower extremity biomechanics by promoting appropriate frontal plane alignment and increased knee flexion during fatigue status. III.