Increased joint space narrowing after arthroscopic partial meniscectomy: data from the osteoarthritis initiative

Purpose: Tibiofemoral joint space narrowing (JSN) can be used to measure the progression of osteoarthritis (OA) because it indicates articular cartilage loss. JSN has been shown to occur after arthroscopic partial meniscectomy (APM). However, it is unclear when the narrowing occurs after APM and how the rate of JSN compares to knees that do not undergo surgery. The purpose of this study was to assess the rate of JSN in knees that underwent APM compared to the rate in matched controls with and without meniscus tear that did not have surgery. Methods: A nested cohort from the multicenter Osteoarthritis Initiative (OAI) study was constructed. The OAI followed patients with knee OA or at high risk for developing knee OA over approximately ten years, and collected patient questionnaires, X-Ray, and MRI at annual visits. A group who underwent APM during the study was identified, and two control groups were assembled by matching to the APM group by sex, age, Kellgren-Lawrence (KL) grade, and follow-up time: a group with meniscus tear based on MRI but who did not undergo APM (WITH TEAR group), and a group who did not have a meniscus tear or undergo APM (NO TEAR group). Patients were excluded for prior knee surgery, less than 12-months follow-up time, or insufficient X-Ray data. Minimum medial compartment joint space width (JSW) using a standardized fixed flexion protocol was used. A piecewise linear mixed effects model was created to model the relationship between rate of JSW loss over time and group, while adjusting for age, BMI, smoking status, KL grade, and baseline JSW. A time spline was included to allow the rate of JSW loss to vary before and after 12 months. Repeated measures structure was specified using an AR(1) variance and covariance structure. A significance level of 0.05 was assumed. Results: 163 knees were included in each group for a total of 489 knees. Mean age was 62.3 years, mean BMI was 29.7 kg/m2, baseline JSW was 4.4 mm, 62% were female, and 40% had KL grade 2. Baseline characteristics of all three groups were similar. The adjusted model showed a significant decrease in JSW over time for all groups (p < 0.001), and an increased rate of JSN over time for the APM group compared to the other groups (p < 0.001), but not for the with tear group compared to the no tear group (p = 0.12). In the APM group, the rate of JSN was over 8 times greater in the first 12 months (p < 0.001), which was not the case for the other groups. JSN was greater with increasing age (p = 0.01), with increasing BMI (p < 0.001), and with lower baseline JSW (p < 0.001). Conclusions: Patients who had an APM had a higher rate of JSN than matched controls with or without a meniscus tear who were treated non-surgically, and the rate of JSN was higher in the first 12 months after surgery. This suggests that APM results in a temporary increase in the rate of radiographic narrowing compared to non-surgical management of meniscus tear with OA. The precise timing of joint space loss following APM is still unclear, as the first postoperative radiograph occurred at varying times during the first year. Multiple factors may contribute to joint space narrowing following APM including loss of interposed meniscus, increased contact stress in the knee, or inflammation induced by surgery. Further study of the relationship between APM and joint space narrowing is merited, including whether this increased narrowing is associated with worsening symptoms or increased progression to total knee replacement.View Large Image Figure ViewerDownload Hi-res image Download (PPT)