Concomitant Medial Meniscal Root Repair with Extrusion Repair (Centralization Technique).

Background: Meniscal extrusion is a phenomenon in which a degenerative posterior horn tear, radial tear, or root tear results in displacement of the body of the meniscus medial to the tibial rim. The paramount function of the meniscus is to provide load distribution across the knee joint. Meniscal extrusion will prevent the meniscus from properly fulfilling this function and eventually leads to progression of osteoarthritis¹. Thus, root repair accompanied by arthroscopic meniscal extrusion repair (by a centralization technique) has been suggested for restoration of meniscal function^2-5. There are various techniques to correct meniscal extrusion, including a dual-tunnel suture pull-out technique² (to address extrusion and root tear²), a knotless suture anchor^4,6 technique, and an all-inside suture anchor repair⁷. The indications for extrusion repair are not consistently reported in the literature, and the procedure is not always easy to perform. Currently, there is no consensus regarding the ideal technique. In the present article, we describe the steps for successful combined medial meniscal root repair with extrusion repair and centralization.

Description: Place the patient in the supine position with the knee supported in 90° of flexion and the feet at the edge of the operating table with foot-positioner support. First, meniscal root repair is performed with use of the suture pull-out technique, utilizing a cinch suture configuration to hold the root in place, and the suture tapes are fixed over the anterior cortex of the tibia with a suture button. Next, the meniscal body is arthroscopically assessed for residual extrusion from the medial tibial rim. Extrusion repair is indicated in cases with >3 mm of extrusion^7-9, as measured on magnetic resonance imaging. In our technique, any extrusion beyond the medial tibial rim is reduced and secured with use of a double-loaded 2.3-mm all-suture type of anchor.

Alternatives: Alternatives include surgical procedures in which the root repair is performed with use of suture-anchor fixation^10,11 and the extrusion repair is performed with use of the transtibial suture pull-out method.

Rationale: Root repair performed with the most common fixation techniques does not always reduce meniscal extrusion or restore meniscal function^12,13. Consequently, several augmentation techniques have been reported to address meniscal extrusion^3,14, including those that use arthroscopy to centralize the midbody of the meniscus over the rim of the tibial plateau. The rationale for this combined procedure is to restore the hoop-stress distribution and maintain meniscal function by repairing the extrusion of the meniscus. Addressing all intra-articular pathologies in a single stage is a challenging situation, and the sequence of the repair is important to achieve optimal postoperative results.

Expected outcomes: Several surgical techniques have been described for the operative treatment of extrusion repair with use of centralization sutures^2,3,5,6, and each has its own distinctive pearls and pitfalls for each. To combine root repair and extrusion repair presents a challenge for surgeons. From our clinical experience, a methodical approach to understanding the pathoanatomy and sequential execution of repair techniques would yield desired results. Extrusion correction through the use of a peripheral suture anchor over the medial rim of the tibia and knot tying are relatively easier to perform than some other published extrusion-repair techniques. Although no consensus has been achieved yet regarding the best technique, recent literature has suggested that the use of centralization sutures is effective to restore the native biomechanical properties of the medial meniscus⁵.Mochizuki et al. assessed the clinical and radiological outcomes of combined medial meniscal root repair and centralization in 26 patients with a minimum follow-up of 2 years. Both Lysholm scores and Knee injury and Osteoarthritis Outcome Scores improved significantly after surgery, with a significant reduction in extrusion distance from preoperatively to 2 years postoperatively²⁰. Koga et al²¹ assessed the 2-year outcomes of lateral arthroscopic meniscal centralization, finding significantly reduced meniscal extrusion at both 3 months and 1 year postoperatively. Biomechanical studies have demonstrated that centralization can improve meniscal mechanics and potentially reduce the risk of osteoarthritis. The centralization suture technique for extrusion repair has the theoretical advantage of restoring meniscal function following meniscal root repair; however, there are also concerns regarding over-constraint of the meniscus. We believe that the medial meniscus, being less mobile than the lateral meniscus, can withstand the constraint created by the use of centralization. Meniscal centralization is a technically demanding surgical procedure, but with a systematic approach and meticulous technique, we have observed good short-term outcome in our patients.

Important tips: A tight medial compartment is one of the most common problems encountered during a medial meniscal root repair. "Pie-crusting" of the superficial medial collateral ligament at the tibial insertion aids in improving the space, thereby reducing chondral damage during the root repair.It is challenging to achieve the correct inclination of insertion when inserting the suture anchor through a mid-medial portal. This limitation can be mitigated by utilizing a 16G or 18G needle before making the portal, as the needle direction, trajectory, and extent of accessibility within the joint will aid in proper portal placement and anchor insertion.Suture management is another technical challenge. Suture tape is first cinched to the root of the meniscus and then shuttled into the transtibial tunnel in order to discern the reducibility of the meniscus and the extent of possible extrusion correction. Then, extrusion repair is performed. This sequence allows the surgeon to avoid mixing of root-repair sutures and extrusion-repair sutures. Following insertion of the all-suture anchor, each suture limb is brought out through the anteromedial portal, passed through the nitinol loop from the lasso, and shuttled back through the mid-medial portal. Knot tying is performed through the mid-medial portal.

Acronyms and abbreviations: ACL = anterior cruciate ligamentPCL = posterior cruciate ligamentICRS grading = International Cartilage Research Society system for classification of cartilage lesionsKL grade = Kellgren-Lawrence system for classification of osteoarthritisMRI = magnetic resonance imagingMC = medial femoral condyleMPTA = medial proximal tibial angleLC = lateral femoral condyleHTO = high tibial osteotomyMCL = medial collateral ligamentAM = anteromedialKOOS = Knee injury and Osteoarthritis Outcome ScoreMME = medial meniscus extrusion.