Is a Strong Quadriceps Muscle Bad for a Patient with Knee Osteoarthritis?

Awareness is increasing that nonpharmacologic measures are the keystone of management of patients with symptomatic knee osteoarthritis (1, 2). Analgesics and nonsteroidal anti-inflammatory drugs augment the benefits of measures such as patient education about principles of joint protection; weight loss (if the patient is obese); and an exercise regimen that improves or maintains range of motion of the involved joint, strengthens periarticular muscles, and improves cardiovascular fitness. However, although a number of studies have described symptomatic benefit in patients with knee osteoarthritis following a variety of types of exercise (3-5), data on whether periarticular muscle strengthening affects the progression of structural damage have been unavailable.

In the study by Sharma and colleagues in this issue (6), greater quadriceps strength at baseline was associated with an increased likelihood of radiographic progression of knee osteoarthritis among patients with varus–valgus laxity of the knee, demonstrated by mechanical testing or varus–valgus malalignment of the knee on full lower-limb radiographs. Radiographic progression was defined as a decrease in the interbone distance in the medial tibiofemoral compartment in paired knee radiographs obtained at an 18-month interval, using a protocol shown to afford reproducible positioning of the joint (7). A decrease in joint space width is generally considered to indicate thinning of articular cartilage. Sharma and colleagues concluded that greater quadriceps strength did not compensate for the adverse effects of malalignment or varus–valgus laxity on progression of cartilage loss in the osteoarthritic knee. They suggested that …