Medial meniscus posterior root tears with advanced osteoarthritis or subchondral insufficiency fracture are good indications for unicompartmental knee arthroplasty at a minimum 2-year follow-up

The outcomes of unicompartmental knee arthroplasty (UKA) in the presence and absence of medial meniscus posterior root tears (MMPRTs) have not been compared. This study compared the characteristics and clinical outcomes of patients undergoing UKA with and without MMPRTs.

This study analyzed 68 patients. The presence or absence of MMPRTs was evaluated using preoperative magnetic resonance imaging. Patient characteristics, clinical scores before surgery and at the final evaluation, and imaging findings were compared between patients with and without MMPRTs. Multiple regression analysis was conducted on postoperative visual analog scale (VAS)-pain scores.

MMPRTs were present in 64.7% (44/68) of patients. Patients with MMPRTs were significantly younger (67.8 ± 8.2 vs. 75.0 ± 7.1 years, p < 0.001) and had a shorter duration from the development of symptoms to the time of surgery than those without (6.8 ± 8.4 vs. 36.1 ± 38.9 months, p < 0.001). Component placement or lower-limb alignment did not significantly differ between the groups. Preoperative clinical scores were not significantly different between the groups; however, patients with MMPRTs showed significantly better postoperative VAS-pain scores than those without (10.0 ± 9.0 vs. 28.2 ± 26.0 points, p = 0.026). Multiple regression analysis of postoperative VAS-pain scores revealed the significant effect of duration from the development of symptoms to the time of surgery (p = 0.038).

Patients undergoing UKA with MMPRTs were younger with less radiographic osteoarthritic changes compared to those without MMPRTs, and their postoperative VAS-pain scores were significantly superior. The duration from the development of symptoms to the time of surgery significantly influenced postoperative pain in patients undergoing UKA.