THE EFFECT OF WEDGED INSOLES ON THE THRUST OF OSTEOARTHRITIC KNEES

We describe a method of quantifying the lateral/medial thrust of the k nee which occurs in the early phase of walking. We have used this meth od to evaluate the effects of wedged insoles on the lateral and medial thrust for normal knees and knees with unicompartment osteoarthritis (OA). A laterally elevated (valgus) insole decreased the lateral thrus t of both normal and osteoarthritic knees. A medially elevated (varus) insole increased the lateral thrust. In 50 symptomatic knees with med ial compartment OA, decreasing the lateral thrust with a valgus insole reduced pain on walking in 27, Patients whose pain was reduced by val gus insoles tended to have earlier OA and to have a significantly grea ter reduction in the lateral thrust than in the 23 remaining unaffecte d knees. A varus insole was effective in decreasing the medial thrust and reducing pain in all ten knees with lateral compartment OA. We rec ommend the use of valgus insoles for patients with painful early media l compartment OA and the use of varus insoles far lateral compartment OA.