Longitudinal changes in medial meniscus extrusion and clinical outcomes following pullout repair for medial meniscus posterior root tears: a 3-year evaluation

Abstract

Purpose: We aimed to evaluate the longitudinal changes in medial meniscus extrusion (MME) and clinical scores at multiple time points up to 3 years after pullout repair for medial meniscus posterior root tears (MMPRTs).

Methods: This retrospective case series study included 64 patients who underwent pullout repair for MMPRTs and four MRI evaluations (preoperatively and at 3 months, 1 year, and 3 years postoperatively). MME was measured during the same time points. Clinical scores were assessed four times: preoperatively and at 1, 2, and 3 years postoperatively. Additionally, a multivariate analysis was performed on the change in MME (ΔMME) from the preoperative measurement point to 3 years postoperatively.

Results: The ΔMME per month from the preoperative measurement point to 3 months postoperatively, from 3 months to 1 year postoperatively, and from 1 to 3 years postoperatively were 0.30, 0.05, and 0.01 mm/month, respectively. All clinical scores significantly improved 3 years postoperatively (p < 0.001). In a multiple regression analysis for ΔMME from the preoperative measurement point to 3 years postoperatively, sex significantly affected the outcome (p = 0.039).

Conclusion: Following pullout repair for MMPRTs with well-aligned lower extremities, although MME progression could not be entirely prevented, the rate of progression decreased over time, and clinical scores improved. In particular, MME progressed markedly during the first 3 months postoperatively. Additionally, sex had a significant influence on MME progression, suggesting that males may be able to expand the indications of pullout repair for MMPRTs.

Keywords: Clinical score; Meniscus; Meniscus extrusion; Osteoarthritis; Posterior root tear.

Fig. 1

Arthroscopic findings of the surgical technique for diagnosis and suture for MMPRTs. A Prior to the outside-in pie-crusting technique, the medial knee compartment appeared narrow and challenging to treat for MMPRTs. B Utilizing an outside-in pie-crusting technique with an 18-gauge needle, the posterior one-third of the medial collateral ligament and the posterior oblique ligament were incised. C Following the outside-in pie-crusting technique, the medial knee compartment was enlarged, facilitating the diagnosis and treatment of MMPRTs. D Two threads were passed 5 and 10 mm from the torn edge of the MMPR using a suture passer device. E Additional sutures were performed using an all-inside meniscal suture device, such as the FasT-Fix system. The first needle was inserted into the inferior aspect of the MM posterior horn in a posteromedial direction. F The second needle was inserted directly into the articular capsule via the undersurface of the MM. MM, medial meniscus; MMPR, medial meniscus posterior root; MMPRTs, medial meniscus posterior root tears

Fig. 2

Arthroscopic findings demonstrating the surgical technique of tibial tunnel creation and pullout repair for MMPRTs. A A custom-made MMPRT guide was used to insert a guide pin into the anatomic attachment of the MMPR at a 45° angle to the articular plane, followed by overdrilling with a 4.0-mm diameter cannula-type drill to create a tibial tunnel. B Using a suture retriever, 2–0 nylon thread was passed through the tibial tunnel. C Three sutures were suture relayed together and pulled out into the tibial tunnel. D Prior to tibial fixation of sutures, additional sutures were visible in the inferior aspect of the MM. E Following tibial fixation of the sutures, additional sutures were concealed under the MM, and the MMPR retracted on the tibial tunnel. F After tibial fixation of the sutures, the MM was lifted with a probe, revealing the additional suture. MM, medial meniscus; MMPR, medial meniscus posterior root; MMPRTs, medial meniscus posterior root tears

Fig. 3

MME measurement. MME (white arrow) was measured as the distance between the medial edge of the MM (blue dotted line) and the tibial plateau excluding the osteophytes (red line) in the slice in which the medial tibial eminence was the highest (white arrowhead) using MRI coronal images. MM, medial meniscus; MME, medial meniscus extrusion; MRI, magnetic resonance imaging

Fig. 4

Longitudinal changes in clinical scores. All clinical scores showed significant improvements at 1, 2, and 3 years postoperatively compared with those preoperatively. The KOOS-symptoms (p = 0.019 and p = 0.003) and IKDC score (p = 0.027 and p = 0.049) showed significant improvements at 2 and 3 years postoperatively compared with those at 1 year postoperatively. In addition, KOOS-Sport/Rec (p = 0.017) and pain VAS score (p = 0.033) significantly improved from 2 to 3 years postoperatively. IKDC, International Knee Documentation Committee; KOOS, Knee Injury and Osteoarthritis Outcome Score; Sport/Rec, sport/recreation function; VAS, visual analog scale *p < 0.05

Fig. 5

Longitudinal changes in MME. MME preoperatively and at 3 months, 1 year, and 3 years postoperatively was 3.95 ± 1.05, 4.84 ± 1.23, 5.25 ± 1.50, and 5.41 ± 1.71 mm, respectively. MME progression was 0.30 mm/month from the preoperative measurement to 3 months postoperatively, 0.05 mm/month from 3 months to 1 year postoperatively, and 0.01 mm/month from 1 to 3 years postoperatively; thus, indicating that the MME progression rate decreased over time. MME, medial meniscus extrusion. *p < 0.05 (vs. preoperative), ^†p < 0.05 (vs. postoperative 3 months)