To evaluate muscle strength changes following partial meniscectomy or exercise therapy for degenerative meniscal tears and the relationship between baseline muscle strength and osteoarthritis progression.
Secondary analysis of a randomized trial (n = 140 participants). Isokinetic quadriceps and hamstrings strength (peak torque [Nm/kg] and total work [J/kg]) were assessed at baseline, 3-month, 12-month, and 5-year follow-up. Between-group differences were analyzed using intent-to-treat linear mixed models. The relationship between baseline muscle strength and osteoarthritis progression (Kellgren/Lawrence ≥1 grade increase) were assessed using logistic regression models.
We found statistically significant between-group differences favoring exercise therapy at 3 months (quadriceps -0.30 Nm/kg [95% confidence interval (95% CI) -0.40, -0.20]; hamstrings -0.10 Nm/kg [95% CI -0.15, -0.04]) and 12 months (quadriceps -0.13 Nm/kg [95% CI -0.23, -0.03]; hamstrings -0.08 Nm/kg [95% CI -0.14, -0.03]). At 5 years, between-group differences were -0.10 Nm/kg (95% CI -0.21, 0.01) for quadriceps and -0.07 Nm/kg (95% CI -0.13, -0.01) for hamstrings. Quadriceps muscle weakness at baseline was associated with knee osteoarthritis progression over 5 years, with adjusted odds ratio of 1.40 for every 0.2 Nm/kg decrease (95% CI 1.15, 1.71). The adjusted odds ratio for hamstrings was 1.14 (95% CI 0.97, 1.35) for every 0.1 Nm/kg decrease.
Exercise therapy was effective in improving muscle strength at 3- and 12-month follow-up compared to partial meniscectomy, but the effect was attenuated at 5 years. Quadriceps muscle weakness at baseline was associated with higher odds of osteoarthritis progression over 5 years.