Medial Meniscal Extrusion Increased on 6-Month Magnetic Resonance Imaging, Despite Successful Posterior Root Repair With or Without a Centralization Suture: A Randomized Controlled Clinical Trial

Background: Meniscal extrusion has been reported to be present in >50% of knees after medial meniscus root repair. Meniscal extrusion has also been reported to be a risk factor for the progression of osteoarthritis and poorer patient-reported outcomes by impairing the ability of the meniscus to absorb hoop stress. Purpose: To determine whether the addition of a centralization suture to 2-tunnel transtibial root repair reduces postoperative medial meniscal extrusion in patients with type 2 posterior medial meniscus root (PMMR) tears. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: This randomized controlled trial was performed between April 2021 and November 2024 for patients with an isolated type 2 PMMR tear. Patients undergoing PMMR repair were randomly selected to undergo transtibial repair with (treatment group) or without (control group) a centralization suture. A power analysis determined that 24 patients were necessary for the study. Magnetic resonance imaging (MRI) was performed preoperatively and at 6 months postoperatively using a high-resolution 7-T scanner. Medial meniscal extrusion was measured on coronal T2-weighted images using 2 vertical lines at the peripheral margins of the medial tibial plateau and the outermost edge of the meniscal body. Statistical analysis was performed using t tests, and significance was set at P < .05. Results: A total of 26 patients (21 female, 5 male) were examined; 14 patients were in the centralization group (treatment group, mean age, 50.3 years), and 12 patients were in the control group (no centralization, mean age, 56.1 years). All PMMR repair constructs were found to be intact on MRI postoperatively. Preoperatively, meniscal extrusion averaged 3.81 ± 1.16 mm for the centralization group and 3.31 ± 0.93 mm for the control group ( P = .244). Postoperatively, meniscal extrusion averaged 4.61 ± 1.52 mm for the centralization group and 5.02 ± 1.33 mm for the control group ( P = .483). In the centralization group, extrusion increased by a mean of 0.81 ± 0.72 mm (21.4% ± 17.7% increase) compared to preoperatively, while the control group experienced a mean increase of 1.71 ± 1.33 mm (59.8% ± 52.6% increase). The increase in extrusion of the centralization group was significantly smaller compared to that of the control group for both the absolute change (in mm; P = .026) and percentage change ( P = .016). Postoperative extrusion increased in 25 of 26 (96.2%) patients. Conclusion: Despite surgically successful PMMR repair in all patients, medial meniscal extrusion was increased in 96.2% of patients at 6 months postoperatively compared to preoperatively. The addition of a centralization suture in transtibial root repair compared to isolated transtibial root repair resulted in a significantly less increase in postoperative extrusion at 6 months on MRI. Registration: NCT05088525 (ClinicalTrials.gov)