Partial meniscectomy provides no benefit for symptomatic degenerative medial meniscus posterior root tears

Medial meniscus posterior root tears (MMPRTs) are recognized as a source of pain and dysfunction, but treatment options remain a challenge. The purpose of the study was to determine (1) the efficacy of partial meniscectomy to treat MMPRTs compared to a matched group of non-operatively treated MMPRTs, and (2) risk factors for worse clinical and radiographic outcome. This retrospective comparative study was performed to include patients with complete, isolated MMPRTs with documented clinical symptoms and were treated with arthroscopic partial meniscectomy (PMM) and a minimum 2-year follow-up. These patients were then matched by age, gender, and BMI to patients with the same diagnosis who were treated non-operatively. Clinical and radiographic outcomes were compared between the two groups. Analysis was performed to determine risk factors for worse clinical and radiographic outcome in the PMM group alone. Overall, 52 patients were included in the study. Twenty-six patients (9M:17F) with a mean age of 55 +/- 9 and a mean BMI of 32.8 +/- 5.3 were treated with PMM and followed for 5.5 +/- 2.0 years (range 2.3-9.3 years). In the PMM group, final median Tegner score was 3, mean IKDC score was 67.8 +/- 20, and more patients had grade II or higher arthritis at final follow-up than baseline (91.3 vs. 36%, p < 0.01). Overall, 14 of the 26 patients (54%) treated operatively progressed to total knee arthroplasty at a mean of 54.3 months. There was no significant difference in final Tegner scores, IKDC, K-L grades, progression to arthroplasty, or overall failure rate between the PMM group and non-operative group. Following PMM, female patients had lower final IKDC scores (44.0 +/- 2.8 vs. 74.6 +/- 16.7, p = 0.02) compared to males, as well as a higher rate of arthroplasty (70.6 vs. 20.0%, p = 0.009). Higher BMI correlated with lower IKDC scores (r = -0.91, p = 0.01) and meniscal extrusion was associated with higher rate of arthritis at final follow-up (p = 0.02). Partial meniscectomy for a complete MMPRT provides no benefit in halting arthritic progression. Patients who undergo PMM for MMPRTs still progress to significant arthritis, poor clinical outcomes and a high arthroplasty rate (54%) at over 5-year follow-up. Female gender, increased BMI, and meniscus extrusion were associated with worse outcome. Level III.