Relationship Between Two Years of Muscle Strength Decrease and Volume Loss of Menisci and Cartilage According to Knee Pain in Mild and Moderate Knee Osteoarthritis.

OBJECTIVE: To explore the relationship between two-year changes in muscle strength and cartilage according to knee pain in mild and moderate knee Osteoarthritis (OA).

DESIGN: 279 participants were retrospectively obtained from the Osteoarthritis Initiative. Western Ontario McMaster University (WOMAC) and Knee Injury and Osteoarthritis Outcome Score were used to assess pain and function. Five muscles strength (maximum extensor and flexor, normalized maximum extensor and flexor, and extensor/flexor ratio) were measured from isometric strength test. Menisci and cartilage volumes were measured from MRI to assess two-year of OA progression.

RESULTS: Mild and moderate knee OA progression was characterized by patellofemoral cartilage loss and meniscal degeneration. For WOMAC pain >2 participants, decrease in extensor strength and normalized extensor strength were positively correlated with medial meniscus volume loss (r = 0.261, P = 0.021; r = 0.232, P = 0.041, respectively). The extensor/flexor ratio changes were positively associated with WOMAC function changes (r = 0.291, P = 0.013) over two-year.

CONCLUSION: The study observed a positive correlation between quadriceps strength decrease and medial meniscus degeneration in mild and moderate knee OA patients with WOMAC pain >2. These findings suggested quadriceps-hamstrings balance possibly plays a protective role in knee function for participants with weaker quadriceps and severe pain.