Special insoles can help reduce pain associated with medial component (inner) knee osteoarthritis. The insoles, known as lateral-wedge insoles, lessen pain by changing the mechanics of the knee.
What Are Lateral-Wedge Insoles?
A lateral-wedge insole is worn inside the shoe. It is thinner at the instep and thicker at the outer edge of the foot. The angle of the lateral-wedge insole can be customized for individual patients.
How Do Lateral-Wedge Insoles Reduce Pain?
Lateral-wedge insoles alter knee biomechanics during walking by reducing what is known as varus torque (twisting of the knee inward). Increased load across the knee joint is associated with the development of knee osteoarthritis. Researchers have suggested that altering the knee load may reduce osteoarthritis symptoms and slow disease progression in knee osteoarthritis patients.
Severe knee pain and extensive x-ray evidence of knee osteoarthritis has been associated with even higher knee adduction (movement towards the midline of the body or inward) when walking. Lateral-wedge insoles can reduce varus misalignment.
Who May Be Helped by Lateral-Wedge Insoles?
Patients with medial knee osteoarthritis may be helped by lateral-wedge insoles. In medial knee osteoarthritis, alignment of the knee becomes varus (twisted inward) as joint space narrows. The lateral-wedge insole helps by correcting the misalignment and shifting the load away from the medial component of the knee.
About 67% of knee osteoarthritis patients have medial knee osteoarthritis, while 10 to 16% have lateral knee osteoarthritis. The rest are affected in the region behind the knee cap (patellofemoral region).
How Effective Are Lateral-Wedge Insoles?
Studies have produced inconsistent results regarding lateral-wedge insoles. While some studies have concluded that lateral-wedge insoles have no significant effect on osteoarthritis symptoms or osteoarthritis progression, another revealed that patients who used lateral-wedge insoles decreased their use of nonsteroidal anti-inflammatory drugs (NSAIDs) and had greater compliance with wearing the insoles. More studies are needed to assess the true benefit of lateral-wedge insoles for knee osteoarthritis. It is considered a conservative treatment option. Discuss the appropriateness of lateral-wedge insoles for you with your doctor.
Special Insole Lessens Pain, Progression of Knee Osteoarthritis. American Academy of Physical Medicine and Rehabilitation. Kerrigan et al. July 5, 2002.
Effects of laterally wedged insoles on symptoms and disease progression in medial knee osteoarthritis. Bennell et al. BMC Musculoskeletal Disorders. September 24, 2007.