A Wedge to Hedge Knee ArthritisOsteoarthritis of the knee affects walking more than any other disease in adults over 65. The medial part of the knee is hurt more than any other place. This is the joint area on the inside of the leg, closest to the other knee. The force from regular activities such as walking is often greatest at this point.Â
Pressure that goes from the ground upward through the foot to the knee is called ground force. A slight twist or rotation of force is called torque. Both pressure and torque are part of the problem. The medial joint space tends to get thin from these two forces repeated over and over. This, in turn, puts more pressure on the joint. A vicious cycle of ground force, joint torque, and damage starts.
One way to change this problem is to wear a wedge inside the shoe. This wedge is placed along the outside edge of the foot. It angles the foot outward five or 10 degrees. This moves the weight off the medial side of the knee and more toward the outside (lateral) joint surface.
A lateral wedge changes the way the patient walks and reduces joint pressure. The material of the insole also cushions the foot. The combined effects provide relief from knee pain. For some patients, the larger wedge (10 degrees) is uncomfortable. The foot feels cramped because of a lack of shoe depth to fit the wedge.
Treatment for knee osteoarthritis often includes weight loss, the use of an assistive device such as a cane, and knee bracing. A proven method is a wedge placed inside the shoe to change the force and pressure on the medial side of the knee. The reduced pain and torque on the knee may even slow down the arthritis.
D. Casey Kerrigan, MD, MS, et al. Effectiveness of a Lateral-Wedge Insole of Knee Varus Torque in Patients With Knee Osteoarthritis. In Archives of Physical Medicine and Rehabilitation. July 2002. Vol. 83. No. 7. Pp. 889-893.