Background/Purpose: Meniscal damage and extrusion are both strongly associated with the progression of knee OA. Concerns have recently been raised that arthroscopic partial meniscectomy (APM) may accelerate OA development. It is currently unclear whether performing APM or leaving a meniscal tear in situ affect meniscus position differently. Thus we determined the effect of APM on medial meniscal body extrusion in patients with OA and meniscal tear.

Methods: Post-hoc analysis using data from the MeTeOR trial (ClinicalTrials.gov number, NCT00597012), a multi-center randomized controlled trial that involved patients aged 45 or older with knee symptoms and meniscal tear as well as osteoarthritic changes detected on MRI (cartilage lesions) or radiography. Patients were randomized to either APM coupled with postoperative physical therapy (PT) or a standardized PT regime. Cross-over from PT to APM due to treatment failure was allowed. One orthopedic surgeon, who was blinded to treatment allocation, actual treatment received, and patient characteristics, but who had knowledge of the time sequence, performed paired meniscal measures on the baseline and 18-month mid-coronal 1.5T knee MR images. The observer measured medial meniscal body extrusion to the closest 0.1 mm using Sante DICOM Editor software. Intra-observer reliability (intra-class correlation coefficient) was 0.85 (95% CI: 0.73-0.92). We defined our primary outcome as the absolute change in mm of the position of the external medial meniscal body margin from baseline to the 18-month exam. We used the intention-to-treat (ITT) principle for the primary analysis, and we also performed a secondary as-treated analysis, i.e., taking into account the cross over after randomization (including those who crossed over from PT to APM into the APM group).

Results: The MeTeOR trial patients have mean (SD) age 59 (7.9) years at baseline and 56% were women. In this analysis we included the first 223 patients who had both baseline and 18-month follow-up knee MRIs available and readable. Of these, 108 patients were randomized to APM and 115 to standardized PT. The mean medial meniscus body extrusion at the baseline exam was similar; mean (SD) 3.2 (1.4) mm in the APM arm vs. 3.4 (1.5) mm in the physical therapy arm (p=0.34). We found no statistically significant difference in the change of extrusion of the medial meniscal body in the ITT analysis; mean (SD) change +0.47 mm (1.6) in the APM arm vs +0.40 (1.6) mm in the PT arm (p=0.72). In the PT arm, 42 patients (36.5%) crossed over to surgery during the 18 months of follow-up, and 4 patients (3.7%) randomized to APM never had the surgery. We did not find statistically significant differences in the corresponding as-treated analysis, mean (SD) change +0.36 mm (1.5) in those having APM (n=146) vs +0.58 (1.8) mm in those patients having PT only (n=77) (p=0.32).

Conclusion: We observed on average small changes in medial meniscal body extrusion over 18 months in MeTeOR trial participants. APM of a meniscal tear in patients with knee OA does not lead to increased meniscal body extrusion as compared to non-operative management.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-effect-of-arthroscopic-partial-meniscectomy-in-patients-with-osteoarthritis-on-meniscal-body-extrusion/