The purpose of this study was to investigate the characteristics of biomechanical and clinical measurements in relation to the knee adduction moment when wearing a standard shoe and a shoe design for individuals with knee osteoarthritis (Flex-OA).
Kinematic and kinetic data were collected from thirty-two healthy individuals (64 knees) using a ten camera motion analysis system and four force plates. Subjects performed 5 walking trials under the two conditions and the magnitude of individuals' biomechanical responses where explored in relation to the clinical assessment of the Foot Posture Index, hip rotation range, strength of hip rotators, and active ankle-foot motion, all of which have been described as possible compensation mechanisms in knee osteoarthritis.
Significant reductions in the first peak of the knee adduction moment (KAM) during stance phase (9.3%) were recorded (p<0.0001). However, despite this difference, 22 of 64 knees showed either no change or an increased KAM, indicating a non-response or negative-response to the Flex-OA shoe. Significant differences were observed between the responder and non-responder subgroups in the hip rotation range ratio (p=0.044) and the hip rotators strength ratio (p=0.028).
Significant differences were seen in clinical assessments of hip rotation range and hip rotator strength between responders and non-responders using a cut-off of 0.02Nm/kg change in the KAM.