Knee osteoarthritis development five years following arthroscopic partial meniscectomy or exercise therapy for degenerative meniscal tears: the odense-oslo meniscectomy versus exercise trial

Purpose: Degenerative meniscal tears per se and partial meniscectomy are strong risk factors for knee osteoarthritis (OA) development. Several randomized controlled trials have found that partial meniscectomy provides no clinically relevant benefit compared to exercise therapy for degenerative meniscal tears. However, long-term follow-up studies of randomized controlled trials are lacking. Hence, the aim of this five-year follow-up of the Odense-Oslo Meniscectomy versus Exercise (OMEX) trial was to compare progression of individual radiographic features of the knee, incident radiographic knee OA and changes in patient-reported outcome measures following partial meniscectomy or exercise therapy for degenerative meniscal tears.

Methods: One hundred and forty middle-aged patients with an MRI-verified degenerative meniscal tear and 97% without radiographic knee OA were included. Participants were randomized to either arthroscopic partial meniscectomy or a 12-weeks exercise therapy program. Tibiofemoral joint space narrowing and marginal osteophytes in the medial and lateral compartment were assessed semi-quantitatively using the OARSI atlas. The risk for progression for each individual radiographic feature was compared between groups. Additionally, a total radiographic score was calculated, and comparison made between treatment groups. Development of incident radiographic knee OA (Kellgren & Lawrence grade ≥2), changes in medial tibiofemoral fixed joint space width (fJSW, quantitatively assessed) and in patient-reported outcome measures (Knee injury and Osteoarthritis Outcome Score [KOOS]) were also compared between groups. Poisson regression with robust standard errors was applied to compare groups with respect to progression of the individual radiographic features and incident radiographic knee OA. The results are presented as risk ratio with 95% confidence intervals (95% CI). All models were adjusted for the stratification variable, gender. Between-group difference in change in total radiographic score was assessed by linear regression, adjusted for gender and baseline value of the outcome. Changes in medial fJSW and in all five KOOS subscales were analyzed by analysis of covariance (ANCOVA), with gender and baseline value of the outcome as covariates. Statistical analyses were performed using a full-set analysis, as well as per protocol and as treated analysis.

Results: Radiographic assessment at the five-year follow-up was performed on 120 participants (86%) (62 participants in the surgery group and 58 in the exercise therapy group). For the surgery group the risk ratios (95% CI) for progression of joint space narrowing and medial and lateral osteophytes were 0.89 (0.55-1.43), 1.15 (0.79-1.67) and 0.77 (0.42-1.42), respectively, compared to the exercise therapy group. The linear regression model indicated no difference between groups in the total radiographic score (B=-0.02, 95% CI -0.51 to 0.49). Sixteen percent in both groups developed radiographic knee OA over the follow-up period (Risk ratio 1.03, 95% CI 0.46 to 2.30). The mean change (95% CI) in medial fJSW was -0.50 mm (-0.69 to -0.30) for the surgery group and -0.30 mm (-0.51 to -0.09) for exercise therapy group. The between-group difference was not statistically significant (p=0.17, 95% CI -0.48 to 0.09). No statistically significant or clinically relevant differences were found between groups for the five KOOS subscales. Per protocol and as treated analysis yielded similar results to the full-set analysis.

Conclusions: We found no statistically significant differences in individual risks for progression of joint space narrowing, marginal osteophytes or change in total radiographic score between surgical and exercise therapy treatments for degenerative meniscal tears. Further, there was no statistically significant or clinically relevant differences between arthroscopic partial meniscectomy and exercise therapy in patient-reported outcome measures.