Toevaluate the clinical efficacy of arthroscopic partial meniscectomy to treat degenerative medial meniscus posterior root tears (MMPRTs) compared to a matched group of conservative treated MMPRTs.

From January 2008 to December 2013, 53 patients (age 45 to 65 years) with degenerative MMPRTs treated in Inner Mongolia People’s Hospital were enrolled in this study, including 26 patients underwent arthroscopic partial meniscectomy and 27 patients received conservative treatment. The patients with K-L grade four, non-simple MMPRTs or a follow-up period of less than five years were excluded. The IKDC score, Lysholm score, Kellgren-Lawrence (K-L)grade and the ratio of total knee arthroplasty (TKA) at five years postoperatively were used for clinical evaluation. Clinical and radiographic outcomes were compared between the two groups. Analysis was performed to determine risk factors for poor clinical and radiographic outcome in the arthroscopic partial meniscectomy group alone. Preoperative and postoperative scores were compared by t test, count data were compared by chi-square test, each risk factor within the group was subjected to COX regression analysis. Joint survival rate was compared by Kaplan-Meier survival analysis.

Twenty-six patients who underwent arthroscopic partial meniscectomy were followed for at least five years, (7.6±2.3) years on anverage. The final IKDC score was (58.7±12.4), Lysholm score was (63.9±21.5), and nine of the 26 patients(34.6%) had grade Ⅱ or higher level arthritis at the final follow-up than baseline. The knee osteoarthritis radiographic progression was 34.6%(8/26), and eight of the 26 patients (30.8%) were treated the operative progression by TKA. There was no significant difference in final IKDC scores, Lysholm score, K-L grades, progression to arthroplasty, or TKA rate between the arthroscopic partial meniscectomy group and conservative group (all P>0.05). In the arthroscopic partial meniscectomy group, the female patients had lower final IKDC scores (48.5±16.2) compared to the males (58.2±11.8), but there was no significant difference(P>0.05). Higher BMI[odds ratio(OR)=0.143, 95% confidence interval(CI)(0.016, 1.283), P=0.022], varus malalignment[OR=2.003, 95%CI(1.131, 6.461), P=0.035], preoperative K-L grade[OR=2.051, 95%CI(1.272, 5.314), P=0.003]and meniscal extrusion[OR=0.105, 95%CI(0.011, 1.051), P=0.045] was associated with higher rate of arthritis at final follow-up.

Compared with conservative treatment, arthroscopic partial meniscectomy for degenerative MMPRTs provides no benefit in delaying the progression of osteoarthritis. Female gender, increased BMI, and meniscus extrusion may associate with worse outcome.