Foot Wedging for Knee Osteoarthritis

Medial knee osteoarthritis is a very common problem that causes substantial pain and disability for the individual and costs to the health care system. Medial knee osteoarthritis is when the osteoarthritis affects the medial compartment or inside part of the knee. Invariably most of these will probably end up needing a knee replacement eventually. The challenge is to help the knee osteoarthritis from getting to the stage where that is needed or to put it off as long as possible. Two of the key risk factors for medial knee osteoarthritis are obesity and what the biomechanists call, a higher knee adduction moment which is related to the angle that forces go through the knee. As obesity is such a major factor, losing weight when you have osteoarthritis is something that is extremely important and all guidelines on this say that a lot of attention needs to be paid to that and taken seriously.

A simple way to reduce that so-called higher knee adduction moment is to use lateral foot wedging in the shoes. This is an insert that is thicker on the outside of the foot than the medial side. This changes the angle of the force going through the knee. This was so promising as a cheaper and simple treatment for medial knee osteoarthritis that several international associations in the 1980’s added this to their guidelines for the recommendations for the treatment of knee osteoarthritis. Since that time a large number of studies in biomechanics laboratories have shown that this is just what they do, so there is a potential that this lateral wedge insert can help. Several studies without control groups at that time also showed that appeared to be very helpful. However, despite the effects of the lateral wedges in biomechanics-based lab studies reducing the force of that risk factor, most of the clinical trial on this that had a placebo or control group showed that they were generally not any better than the placebo. This led to the most recent recommendations on medial knee osteoarthritis is to not use the lateral wedge in the shoe to treat the problem.

Many clinicians are still using the lateral wedge to try and help this despite the guidelines. When you look closer at the data in the clinical trials that generally show that the wedges do not work, it does show that some people are helped. They also show that other people are not helped and in a few the wedge can make the symptoms worse, so on average, the wedges do not work. The challenge now is to work out which people with medial knee osteoarthritis that the wedges can possibly help and use them in those people rather than just use them as blanket treatment for everyone with medial knee osteoarthritis. The cost of the material to make the insert to go in the footwear is pretty minimal compared to the cost of the drugs and surgery that is needed to treat this problem, so it is worth pursing research on this to try and find a solution.

Craig Payne is a University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger and a dad.