Keywords Osteoarthritis, knee adduction moment, gait modification, feedback, wireless sensor insole
Background The knee adduction moment (KAM) is a surrogate measure of mediolateral distribution of loads across the knee joint and is correlated with progression and severity of knee osteoarthritis (OA). Existing biomechanical approaches for unloading the arthritic medial knee compartment vary in their effectiveness in reducing KAM. This study employed a completely wireless, pressure-detecting shoe insole capable of generating auditory feedback via a smartphone. Research question: To investigate whether auditory cues from a smartphone can prompt subjects to adjust their gait pattern and reduce KAM. Methods: Nineteen healthy subjects underwent gait training inside the lab (Phase 1) and received auditory cues during mid- and terminal stance to medialize their foot COP (center-of-pressure). This initial training period was continued unsupervised while walking around campus (Phase 2).
Results After Phase 1, subjects reduced their KAM by 20.6% (p= 0. 001), a finding similar to a previous study that used a wired, lab-based insole system. After further unsupervised training outside the lab during Phase 2, subjects were able to execute the newly learned gait pattern without auditory feedback still showing a KAM reduction of 17.2% (p < 0.001). Although, speed at Phase 2 was lower than at baseline (p= 0.013), this reduction had little effect on KAM (r=0.297, p= 0.216). In addition, the adduction angular impulse was reduced (p= 0.001), despite the slower speed.
Significance Together, these results suggest that the wireless insole is a promising tool for gait retraining to lower the KAM and will be implemented in a home-based clinical trial of gait retraining for subjects with knee OA.