Lateral wedge insoles or inserts are used to help with the symptoms of peroneal tendonitis, chronic ankle instability and medial knee osteoarthritis.
Lateral wedge insoles are orthopedic devices designed to be placed inside footwear to address specific biomechanical issues related to the lower extremities, particularly the knee joint. These insoles are thicker on the lateral (outer) side and taper towards the medial (inner) side.
The primary purpose of lateral wedge insoles is to redistribute the forces acting on the knee and ankle joint during walking or other weight-bearing activities.
This approach is somewhat controversial as, while it can help some people, it can also increase the risk for other problems as it everts or pronates the foot some more. See this discussion on Podiatry Arena about this issue.