Meniscus Centralization

Meniscus Root Repair: Centralization

Max Whooley MS1, Brian Gilmer, MD

Introduction

Meniscus centralization is an arthroscopic surgical procedure in which the midbody of the meniscus is anchored to the border of the tibial plateau with sutures in order to treat or prevent meniscus extrusion caused by meniscus tears, knee surgeries, and congenital abnormalities like discoid meniscus.^1,4,5 It is intended to preserve meniscus function by improving meniscus mechanics to partially restore normal load distribution in the knee.^2,5,6 Theoretically this procedure will reduce articular cartilage damage and prevent the progression of osteoarthritis.² It is unclear whether meniscal pathology is the causative factor in the development of osteoarthritis or vice versa⁷, but both meniscus extrusion and failure to repair meniscus tears have been associated with rapid progression of osteoarthritis.^1-4,6 This procedure has been shown to reduce the incidence of meniscal extrusion when performed in conjunction with procedures like meniscus pullout repair³, partial meniscectomy^1,4, meniscoplasty for discoid meniscus^1,4, and meniscus transplantation^1,4.

Background

The menisci are crescent-shaped structures made of fibrocartilage sitting between the condyles of the tibia and femur.⁷ They function to absorb shock and distribute load in the knee joint by converting axial forces into cylindrical hoop stresses.^4,7 This is necessary to ensure optimal tibiofemoral mechanics and to protect the articular cartilage.^4,6 If the meniscus is damaged by a tear injury or surgical intervention, it may be displaced and extend beyond the peripheral margins of the tibia⁷. This is called meniscus extrusion, which can increase the contact pressure of the cartilage between the femur and tibia, leading to degeneration and rapid progression of osteoarthritis.^6,7 Most meniscus tears have an extrusion extending 2-4 mm beyond the joint margin, and extrusions greater than 2 mm should be considered clinically significant. Extrusion can occur in both the medial and lateral meniscus, although it is more common in the medial meniscus.⁸ Knee joint load is greater in the medial compartment than the lateral⁸, but the medial load is distributed evenly between the medial meniscus and the medial articular cartilage.^1,4 The lateral meniscus, by contrast, bears about 70% of the lateral compartment load. Therefore, extrusion of the lateral meniscus results in a more significant load-bearing functional loss and more rapid cartilage degeneration.^1,4 This discrepancy in relative load-bearing functions might also explain why degenerative tears usually involve the medial meniscus and traumatic tears usually involve the lateral meniscus.⁷

Figure1: Progression of meniscal extrusion from ligament stress becoming a tear and osteoporosis of the medial tibial head

Image retrieved form www.researchgate.net

Indications

Meniscus centralization is indicated to repair or prevent extrusion in patients with symptomatic knee pain, swelling, or catching after conservative treatment⁴ who have:

• Meniscus extrusion >3 mm^3,4
• Extrusion following meniscectomy, discoid repair, or transplantation⁴
• Failed extrusion reduction following root repair³
• Planned meniscus repair, meniscectomy, meniscoplasty, or transplantation^2-4
• Osteoarthritis following meniscus injury and/or meniscectomy⁴
• Symptomatic torn discoid meniscus⁴
• Posterior meniscus root or horn tears²
• Radial and horizontal tears²

Causes of Meniscus Extrusion

Meniscal extrusion can occur as a complication of:

• Meniscus root/horn tears⁸
• Radial tears >50% of meniscus width⁸
• Large complex meniscus tears⁸
• Partial meniscectomy^1,4
• Discoid meniscus repair^1,4
• Meniscus transplantation^1,4
• ACL reconstruction⁷

Diagnosis & Pre-Operative Planning

Your doctor will perform a complete history and physical knee examination to evaluate a possible meniscus injury. Magnetic resonance imaging (MRI) is used preoperatively to confirm and diagnose the meniscus tear, along with the extrusion if present.^1,4,6

Figure2: MRI of knee. Red circle indicates meniscus tear. Green circle indicates meniscus extrusion.

Surgical Procedure

Meniscus centralization can be performed concomitantly with procedures that repair, partially remove, reshape, or transplant a damaged meniscus in order to prevent the postoperative extrusion or correct an existing extrusion associated with the original injury.^2-4 It can also be done in conjunction with other knee surgeries like ACL reconstruction.⁴ In patients with a meniscal extrusion causing knee osteoarthritis following a partial meniscectomy, centralization may be performed alone given no other meniscal pathology or complicating injuries are present.^1,4 This procedure is performed under general anesthesia and requires the patient in a supine position with a tourniquet on the upper thigh of the operated leg.^2,3,6 Based on the available literature, an optimal surgical technique for correcting meniscus extrusion has not been determined.⁷ Two techniques described in the literature for medial and lateral meniscus centralization are outlined below:

Medial meniscus centralization (with concomitant intervention): A 3 cm incision is made at the medial proximal tibia. If a medial meniscus posterior root tear (MMPRT) repair is planned, the medial collateral ligament (MCL) is elevated using a rasp to ensure there is enough working space and accessibility during the procedure.^2,3 Alternatively, the MCL can simply be lengthened by application of valgus force to the knee, and the surgeon can choose to instead elevate the meniscotibial ligaments using a Bankart elevator.⁶ A MMPRT repair is usually performed before centralization, but the sutures securing the posterior root are not fixed until after, because doing so beforehand will hinder the centralization process.^2,3 Repairs of radial and horizontal tears are typically done entirely after centralization.² In cases of lower extremity varus malalignment placing excessive compressive forces on the medial compartment, a high tibial osteotomy can also be performed.^2,3 Following the incision and necessary adjustments, the surgeon will conduct an arthroscopic exam using an anteromedial and anterolateral portal to evaluate the medial meniscus tear, confirm the extrusion, and identify any cartilage damage, osteochondral lesions, or loose bodies which will be addressed accordingly.^2,3,6 An accessory anteromedial⁶ or mid-medial portal² is created to ensure proper orientation of instruments and accessibility during the procedure.^2,6 If bone spurs are found on the tibial plateau, they are removed using an osteotome through the mid-medial portal.² At this point, the surgeon would begin an MMPRT repair if indicated, but delay fixation until after centralization.³ The surgeon separates the meniscotibial capsule from the tibial plateau with an arthroscopic rasp and corrects the extrusion.² Three knotless suture anchors are inserted and deployed posteromedial to the medial meniscus.^2,6 Physician preference will decide which portals are used for insertion, but a posteromedial portal can be made to facilitate appropriate anchor placement.⁶ The surgeon starts from the posteromedial midbody of the meniscus and works anteriorly to secure the anchors between the meniscotibial capsule and the edge of the tibial plateau. Each anchor is sutured about 1 cm anterior to first. This process requires three repair sutures and the simultaneous use of other devices inserted through the various portals such as a shuttling suture loop, a suture passer, micro suture lasso, suture relay, and cannula.^2,6 At this point, the surgeon would complete fixation of a MMPRT repair or begin a radial/horizontal meniscus tear repair if indicated. A final arthroscopic exam is done to confirm successful extrusion reduction, meniscus repair, and centralization with sufficient tension.^2,3

Isolated lateral meniscus centralization: The surgeon will conduct an arthroscopic exam using an anteromedial and anterolateral portal to evaluate the lateral meniscus tear, confirm the extrusion, and identify injuries such as ACL tears, osteochondral lesions, or meniscal cysts which will be addressed accordingly. A motorized shaver is used to remove some cartilage from the edge of the lateral tibial plateau to prepare for centralization. The surgeon creates a mid-lateral portal and inserts the first suture anchor on the lateral edge of the tibial plateau. Just anterior to the popliteal hiatus (lateral to the meniscus but medial to the joint capsule), the surgeon secures the first anchor between the meniscotibial capsule and the edge of the tibial plateau and secures the second anchor about 1 cm anterior to first. This process requires two repair sutures and the simultaneous use of other devices inserted through the various portals such as a shuttling suture loop, a suture passer, micro suture lasso, suture relay, and cannula. The sutures are eventually tied with a self-locking sliding knot and successful centralization is confirmed.^1,4 

Figure 3: Picture of anchoring the meniscus with sutures to the tibia plateau during meniscus centralization procedure.

Advantages

• Reduce risk of and/or correct meniscus extrusion following repair of meniscus tears, partial meniscectomy, meniscoplasty, & transplantation^1,4
• Reduce risk of meniscus extrusion following ACL repair⁷
• Prevent progression of osteoarthritis²
• Restore proper load distribution in knee joint⁵
• Can replace transplantation as the preferred surgical intervention to restore meniscus function after extrusion^1,4
• Reduced failure risk of root tear repair sutures due to load-sharing with centralization sutures³

Risks and Complications

Possible risks and complications associated with meniscus centralization include:

• Cartilage injury⁶
• Fixation failure⁶
• Recurrent extrusion⁴
• Reduced meniscal motion during knee extension & flexion^1,3
• Loss of knee motion⁴
• Tear of sutured meniscus or new meniscal tear⁴

Postoperative Care

The postoperative protocol for meniscus centralization is the same as that of a standard meniscus repair. Full range of motion exercises are encouraged immediately after surgery. A knee brace and protected weight bearing is needed for the first six weeks with range of motion limited 0-90 degrees. The patient should not begin full weight bearing until six weeks post-op. Hiking starts around 3 months. Running and squatting past 90^° is typically acceptable after 4 months. Patients typically return to their normal athletic activity between 4-6 months post-op.^2,3 If concomitant injuries and/or surgeries occurred, the rehabilitation protocol may require more restrictive guidelines.⁶

Dr. Gilmer’s Take

Centralization is an interesting topic among arthroscopic knee specialists. While this topic is pretty new, I have used this technique in a couple of instances. The first is to augment a meniscal root repair to prevent extrusion. This is because with these root tears, it is like cutting the metal band around a barrel, the whole barrel will fall apart.

The other reason I have done this is less common, but when there is extrusion and pain without a meniscal root tear. There is some early evidence to suggest that the extrusion may precede the root tear and when the extrusion is already symptomatic and painful centralization can be performed to prevent a root tear and overload of the joint.

I do not use a centralization to the bone on the lateral side of the knee because the lateral meniscus is supposed to have more natural motion. In thoses cases, I use a capsular based repair stitch to reduce tension on the root repair.

The other techniques can be used to secure the entire meniscus external to the joint, but I tend to prefer an intraarticular (or in the joint) approach with arthroscopy. I look forward to seeing more on this topic as it evolves.

Biography: Max Whooley is a first-year medical student attending Creighton University School of Medicine in Phoenix, Arizona.

References

1. Koga, Hideyuki, et al. "Arthroscopic centralization of an extruded lateral meniscus." Arthroscopy Techniques 1.2 (2012): e209-e212.
2. Koga, Hideyuki, et al. "Arthroscopic centralization using knotless anchors for extruded medial meniscus." Arthroscopy techniques 10.3 (2021): e639-e645.
3. Koga, Hideyuki, et al. "Augmentation of the pullout repair of a medial meniscus posterior root tear by arthroscopic centralization." Arthroscopy techniques 6.4 (2017): e1335-e1339.
4. Koga, Hideyuki, et al. "Two-year outcomes after arthroscopic lateral meniscus centralization." Arthroscopy: The Journal of Arthroscopic & Related Surgery 32.10 (2016): 2000-2008.
5. Kubota, Rei, et al. "The effect of a centralization procedure for extruded lateral meniscus on load distribution in porcine knee joints at different flexion angles." BMC musculoskeletal disorders 21.1 (2020): 1-8.
6. Leafblad, Nels D., et al. "Arthroscopic centralization of the extruded medial meniscus." Arthroscopy techniques 10.1 (2021): e43-e48.
7. Makiev, Konstantinos G., et al. "Clinical significance and management of meniscal extrusion in different knee pathologies: a comprehensive review of the literature and treatment algorithm." Knee Surgery & Related Research 34.1 (2022): 1-11.
8. Muzaffar, N., et al. "Meniscal extrusion in the knee: should only 3 mm extrusion be considered significant? An assessment by MRI and arthroscopy." Malaysian Orthopaedic Journal 9.2 (2015): 17.