The two main risk factors for medial knee osteoarthritis is obesity and a higher external knee adduction moment. Laterally wedging the foot or shoe has been shown to reduce this adduction moment in many people (but not all) and clinical trials appear to show that it is helpful in many people (but not all). Some review have recently concluded that they may not be beneficial. However, the response to lateral wedges is very subject specific, in that it is hypothesised that those with a more rigid foot may be more responsive to lateral wedging of the foot.

Also of interest is that no research has yet shown any increase in foot problems with the use of lateral wedges. For the latest on the research see: Lateral Wedging for Medial Knee Osteoarthritis.