The variable-stiffness shoe being developed at Stanford University not only reduces external knee adduction moment but also produces corresponding decreases in load within the joint, according to new in vivo data.
The shoe (see “OA research: It’s all about the shoes,”) features a lateral sole that is 1.3 to 1.5 times stiffer than the medial sole, which has been shown to reduce knee adduction moment by up to 20% in patients with knee osteoarthritis.
In the current study, the Stanford investigators analyzed the shoes’ effect on loading in a single subject who was implanted with an instrumented knee prosthesis. As expected, the experimental shoes significantly reduced first peak knee adduction moment (by 13%) compared to the subject’s personal shoes. In addition, joint contact force within the medial compartment was also significantly decreased (12.3%) in the variable-stiffness shoe. The correlation between the external load reduction and the in vivo load reduction was significant and moderately strong (R=.67).
The findings were published in the December issue of the Journal of Orthopedic Research.
By Jordana Bieze Foster