Correlation and comparison of quadriceps endurance and knee joint position sense in individuals with and without unilateral knee osteoarthritis

Background: Knee osteoarthritis (KOA) is a painful degenerative joint disease that may limit activities of daily living. This study aimed to determine the relationship between quadriceps endurance and knee joint position sense (JPS) in KOA individuals and compare the quadriceps endurance and knee JPS with and without KOA. Methods: This comparative cross-sectional study was conducted in medical rehabilitation clinics, King Khalid University, Saudi Arabia. This study recruited 50 individuals diagnosed with unilateral KOA (mean age = 67.10 ± 4.36 years) and 50 asymptomatic individuals (mean age = 66.50 ± 3.63 years). Quadriceps isometric endurance capacity (sec) was measured using a fatigue resistance test, and knee JPS (degrees) were assessed using a digital inclinometer and evaluated in sitting and standing positions. Results: Quadriceps isometric endurance showed a significant moderate negative correlation with knee JPS in 20° of flexion (r = -0.48, p < 0.001); 40° of flexion: r = -0.62, p < 0.001; 60° of flexion: r = -0.58, p < 0.001) in sitting and 20° of flexion (r = -0.25, p = 0.084) in standing position in KOA individuals. When compared to the asymptomatic, the quadriceps endurance was lower (p < 0.001), and knee joint position errors were larger (p < 0.001) in KOA individuals. Conclusion: Results of this study showed that quadriceps endurance capacity is negatively associated with knee JPS. KOA individuals demonstrated lower quadriceps endurance and larger JPS compared to asymptomatic.