Meniscus Centralization in Medial Meniscus Posterior Root Repair

Abstract

Background:

Meniscal root tears have an estimated prevalence of 60 to 70 persons per 100,000, and they have gained increased interest recently. Meniscal extrusion is defined as an extrusion >3 mm for medial meniscus tears from the tibial articular cartilage. Root tear–associated meniscal extrusion has been associated with degenerative cartilage damage, particularly since it contributes to increased tibiofemoral stresses during axial loading.

Indications:

Medial meniscus extrusion >3 mm in the setting of medial meniscus posterior root horn tears.

Technique Description:

The medial meniscus is released from the capsule from its body to the posterior horn. The medial meniscus root is repaired using the pullout technique. The meniscus body is then centralized using a 1.8-mm single-loaded, all-suture, knotless anchor. Additional all-inside sutures are added for increased stability and enhanced healing of the meniscus.

Results:

Two- and 3-year outcomes demonstrated a significant decrease in meniscal extrusion following centralization at the time of medial meniscus posterior root repair, and no conversion to total knee arthroplasty was reported.

Discussion/Conclusion:

Medial meniscus centralization provides increased contact surface between the femur and tibia and thus helps prevent progression of knee osteoarthritis in the early follow-up.

Patient Consent Disclosure Statement:

The author(s) attest that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract.

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DOI: 10.1177/26350254251349857.M1

Background

Relevant disclosures are as listed.

Meniscal root tears were first described in 1991 by Pagnani et al. ⁹ as either radial tears located within 1 cm of the meniscal attachment or a bony soft tissue root avulsion.

Their estimated prevalence was reported as 60 to 70 persons per 100,000, and they have gained increased interest recently.

Multiple biomechanical studies demonstrated that avulsion of the medial meniscus posterior root results in loss of both hoop stresses and meniscal function, exposing the cartilage to supraphysiologic loads, decreased tibiofemoral contact area, and increased peak contact pressures similar to those of a total meniscectomy.^1,4,10

Indications

Meniscal extrusion is defined as an extrusion >3 mm for medial tears from the tibial articular cartilage.^6,11 Root tear–associated meniscal extrusion was associated with degenerative cartilage damage, particularly since it contributed to increased tibiofemoral stresses during axial loading. ³

At this point, we know that unaddressed root tear and extrusion result in rapidly progressing end-stage knee osteoarthritis. ⁷

Patients with meniscus root tear usually present in an acute traumatic setting or a degenerative setting. Medial meniscus posterior root tear develops in the degenerative setting, while lateral meniscus posterior root tear develops in the traumatic setting. ⁶ The best diagnostic imaging technique is T2-weighted sequences. If the extrusion is 3 mm or larger, the meniscus can be considered extruded and indicated for a centralization procedure.

For the preoperative planning, first, the presence of a medial meniscus root tear is confirmed on magnetic resonance imaging by checking the truncation sign on coronal images and the ghost sign on sagittal images. Also, the grade of osteoarthritis is defined based on the Kellgren-Lawrence system. Grade 3 or 4 is not indicated for a root repair and thus centralization procedure. ² Also, chronic tears, patients with a high body mass index, and patients who cannot tolerate nonweightbearing or touchdown weightbearing should be carefully evaluated. The amount of extrusion is measured by the technique described by Costa et al. ³ In this particular patient, the amount of extrusion of the medial meniscus is measured as 4.2 mm.

For surgery, the patient is positioned supine. We prefer using a well-leg holder for the operative extremity and also a leg holder for the contralateral lower extremity.

Technique Description

The arthroscopic surgery starts with a diagnostic arthroscopy, and the root tear is identified. In cases where viewing is limited, we prefer medial collateral ligament pie crusting for better visualization, as seen in this patient. We also utilize a transpatellar portal for viewing. Next, we free the meniscus from the capsule from the body to the posterior horn using a shaver and an arthroscopic punch. The frayed edge of the posterior horn is also debrided. Here, we check the meniscus mobility with a probe and continue to mobilize the meniscus. Once we are satisfied with the mobility, we prepare the medial meniscus posterior root tibial attachment for the tunnel and tibial guide. We then drill a transtibial tunnel coming out exactly where the original root attachment is. The drill bit is then flipped and retro drilled for about 5 mm, which will allow the meniscus root to be flush on the tibial plateau. A wire loop is then introduced, and a loop suture is shuttled into the tunnel.

Next, a luggage tag suture is placed about a centimeter medial to the end of the meniscus. Then, a second suture is placed the same way. One important point to mention is, as the second suture is passed, the suture passer crosses the first suture from medial and comes out more lateral. This will allow the second suture to guide the first suture into the tunnel.

We then move to the meniscus centralization procedure. A medial accessory portal is made at the body of the medial meniscus. Next, using the accessory portal, the drilling guide is placed on the tibia and drilled. Then, a 1.8-mm Knotless FiberTak, single-loaded all-suture, knotless anchor (Arthrex) is deployed. The passing suture is then grasped from the undersurface of the meniscus with a ring grasper, shuttled through the anterolateral portal, and loaded on a suture passer. First, the suture is passed from under to above, and a second suture is passed from above to under. Then, the thin loop suture is grasped with the ring grasper and shuttled through the anterolateral portal. The passing suture is passed through the loop suture until the purple line, and the thick passing suture is pulled to create the knotless suture mechanism. The tightness of the suture can be adjusted according to the surgeon's preference.

Next, the root repair sutures are shuttled through the tibial tunnel using the pullout technique. They are then fixed on the tibia with an anchor based on the surgeon's preference at 90° of knee flexion. The freed meniscus is then fixed back to the capsule using all-inside and/or inside-out suture based on the surgeon's preference.

Potential complications include saphenous nerve injury, meniscus tear through the suture, and popliteal artery injury. All these can be avoided by knowing the anatomy and being familiar with the instruments used.

Results

After surgery, patients are allowed for touch-down weightbearing for 6 weeks with the knee locked in extension in a brace when walking. Physical therapy starts at 2 weeks to work on range of motion up to 90° and quad strengthening.

Full weightbearing is allowed around week 6. At that time, patients discontinue the brace, wean off the crutches, and increase knee flexion and weightbearing, as tolerated. Squatting beyond 90° is not allowed in the first 4 months.

Patients increase their activity around 3 months, and return to sports is allowed between 4 and 6 months if they have normal quadriceps strength and normal gait.

Discussion/Conclusion

Two case series have been reported so far about meniscus centralization in the setting of meniscus root repair. In the first study, Mochizuki et al ⁸ reported on 26 patients at a mean 35-month follow-up with a minimum of 2 years. They reported a significant decrease in the meniscus extrusion from 4.8 to 2.7 mm, and the ratio of extruded meniscus decreased from 40% to 22.6%. At the last follow-up, there was no change in the alignment. All Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales have also improved at follow-up.

In a more recent study, Krych et al ⁵ reported on 25 patients at a 2-year follow-up with a minimum 1-year follow-up. Meniscus extrusion decreased from 3.3 to 1.6 mm. They reported significant improvement in the visual analog scale at rest and, with use, International Knee Documentation Committee score, and KOOS Jr. They also noted no osteoarthritis progression, revision meniscus surgery, or conversion to total knee arthroplasty.

These are our references.

Thank you.