Greater quadriceps strength protects against cartilage loss at the lateral compartment of the patellofemoral joint in persons with knee osteoarthritis (OA), and persons with greater quadriceps strength are likely to have less knee pain and better physical function. Greater quadriceps strength has no influence on cartilage loss at the tibiofemoral joint.
Amin and associates evaluated 265 persons in a 30-month natural history study of knee OA. Cartilage morphology was scored using MRI at baseline and at 15 and 30 months, and baseline quadriceps strength was measured isokinetically for each leg. Long-limb films were used to evaluate alignment at the knee. Knee pain and physical function were assessed.
No association between quadriceps strength and cartilage loss was found in the medial or lateral tibiofemoral joint compartment or in the medial patellofemoral compartment, even in malaligned knees. However, stronger quadriceps protected against cartilage loss at the lateral compartment of the patellofemoral joint, a finding that needs confirmation. Participants in the highest tertile of quadriceps strength had significantly less knee pain and better physical function than those in the lowest tertile.
The authors noted that the focus of their study was on quadriceps strength and not on strengthening or exercise.