How to measure responses of the knee to lateral perturbations during gait? A proof-of-principle for quantification of knee instability.
Knee instability is a major problem in patients with anterior cruciate ligament injury or knee osteoarthritis. A valid and clinically meaningful measure for functional knee instability is lacking. The concept of the gait sensitivity norm, the normalized perturbation response of a walking system to external perturbations, could be a sensible way to quantify knee instability. The aim of this study is to explore the feasibility of this concept for measurement of knee responses, using controlled external perturbations during walking in healthy subjects. Nine young healthy participants walked on a treadmill, while three dimensional kinematics were measured. Sudden lateral translations of the treadmill were applied at five different intensities during stance. Right knee kinematic responses and spatio-temporal parameters were tracked for the perturbed stride and following four cycles, to calculate perturbation response and gait sensitivity norm values (i.e. response/perturbation) in various ways. The perturbation response values in terms of knee flexion and abduction increased with perturbation intensity and decreased with an increased number of steps after perturbation. For flexion and ab/adduction during midswing, the gait sensitivity norm values were shown to be constant over perturbation intensities, demonstrating the potential of the gait sensitivity norm as a robust measure of knee responses to perturbations. These results show the feasibility of using the gait sensitivity norm concept for certain gait indicators based on kinematics of the knee, as a measure of responses during perturbed gait. The current findings in healthy subjects could serve as reference-data to quantify pathological knee instability.
['van den Noort|Josien C|JC|', 'Sloot|Lizeth H|LH|', 'Bruijn|Sjoerd M|SM|', 'Harlaar|Jaap|J|']
D000328:Adult D000070598:Anterior Cruciate Ligament Injuries D001696:Biomechanical Phenomena D005260:Female D005684:Gait D006801:Humans D007593:Joint Instability D007719:Knee Joint D008297:Male D055595:Mechanical Phenomena D020370:Osteoarthritis, Knee D016059:Range of Motion, Articular
Knee Perturbations Gait Instability Anterior cruciate ligament injury Osteoarthritis Gait sensitivity norm