Lower Extremity Muscle Strength and Risk of Hip/Knee Osteoarthritis

PURPOSE: The purpose of this study was to investigate the association between lower extremity muscle strength and the development of self-reported, physician-diagnosed hip/knee osteoarthritis (OA). METHODS: Subjects (4172 men, 837 women) were participants in the Aerobics Center Longitudinal Study (Dallas, TX) who were free of arthritis and joint pain/stiffness/swelling at baseline, completed a clinical examination (1981–90) and returned a mailed follow-up survey (1990, 1995 or 1999). Quadriceps and hamstring muscle strength was measured at baseline by a Cybex isokinetic dynamometer and 1 maximum repetition isotonic leg press (LP) test. Isokinetic quadriceps (QPT) and hamstring (HPT) peak torque values were standardized using body weight. Reciprocal muscle group ratios (Q/H%) were computed using the formula HPT/QPT* 100. Physician-diagnosed hip/knee OA was self-reported on the follow-up survey. Multiple logistic regression was used to calculate sex-stratified odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Almost 7% of men and 8.3% of women reported new onset of hip/knee OA during the follow-up period. In unadjusted analyses, higher QPT, HPT and LP (women only) values were significantly associated with lower risk of hip/knee OA. Higher Q/H% was associated with a higher risk of OA (men only). After adjustment for age, body mass index, previous injury, smoking status and length of follow-up, higher Q/H% significantly increased the risk of OA among overweight/obese men only. CONCLUSION: These data suggest that the neuromuscular system may play an important role in the development of OA, specifically, reciprocal muscle group imbalance may contribute to the development of OA among men with BMI > = 25. Supported by NIH NIA AG06945