Background and Objective: Muscle weaknesse particularly in association with quadriceps muscle is known as a risk factor in the development and progression of knee osteoarthritis (KOA). The objective of this study was to compare quadriceps muscle strength (QMS) between asymptomatic controls and KOA patients and to elucidate its relationship with knee pain and radiographic changes.

Materials and Methods: 77 patients with mean age of 53.6 ± 9.8 years and 75 asymptomatic controls with mean age of 55.8 ±2.8 (p=0.06) and respective BMI of 28.3±4.7 and 25.8 ±2.7 kg/m2 comprised the study. Diagnosis of KOA was confirmed by the criteria of American College of Rheumatology. QMS was determined by dynamometry method radiographic changes were assessed through Kellgren-Lawrence method, and Knee pain was measured using WOMAC index.ْ Statistical analysis was performed to compare QMS between two groups and to evaluate the relationship of QMS to knee pain and radiographic changes.

Results: QMS in both limbs of the experimental group was significantly lower than the control group. The magnitude of reduction in both limbs was significantly lower in men (30.1%) than in women (31.6%) (p=0.002 and p=0.001, for both limbs). There was no relationship between QMS and knee pain or radiographic changes.

Conclusion: In knee osteoarthritis, quadriceps muscle strength is lower compared with healthy controls regardless of pain or radiographic changes.