Wearing a wedge insole inside the shoe may help patients with early and mild medial knee osteoarthritis. Medial refers to the inside compartment of the joint — the side closest to the opposite knee.
The Researchers at the Gait Analysis Laboratory, Division of Physical Therapy, Fukui University in Japan made a study of patients wearing a lateral wedged insole inside the shoe. The idea is to shift some of the weight off the medial joint by moving the weight slightly to the inside of the foot.
Each patient was fitted with light-emitting diodes from the hip to the thigh. Walking was analyzed using a special computerized system. As the patient walked, a light measuring device and force plates captured walking speed, stride width, and step length. X-rays taken also recorded hip-knee-ankle angles. The same measurements and analysis were made with and without the wedge.
Computer analysis of the results showed decreased step length, stride width, and walking speed in patients with OA but without the wedge. These measurements were compared to healthy normal adults in a control group. After wearing the lateral wedged insoles, the stride width changed but length and speed did not change.
Beneficial changes were only observed in patients with mild (grade 1 or 2) medial knee OA. Dynamic load on the knee while walking is known to be linked with severity of disease. If the knee can be unloaded with a simple wedge insert, the progression of OA may be slowed. Patients may experience less pain and become more active.
The results of this study support the use of a lateral wedged insole for anyone with Grades 1 and 2 medial knee OA. Since measurements were taken right after wearing the wedge insoles, the authors suggest another study to measure the results after several months.