Meniscal Root Repair

Introduction

Meniscal root repair is a surgical procedure that can be indicated in the treatment of severe, symptomatic meniscal root tears located in the knee. Case series suggest that meniscal root repair can successfully treat symptomatic isolated meniscal root tears, improving pain and function.

In simpler terms, a meniscal root tear is a serious injury where the meniscus, a piece of cartilage that provides a cushion between your thighbone and shinbone, becomes detached from its anchoring point in the knee. This procedure aims to reattach the torn meniscal root to its place, restoring the normal function of the meniscus.

Indications

Meniscal root repair is indicated in symptomatic meniscal root tears, patients with a stable knee or those who have undergone concurrent procedures to achieve stability, patients without significant osteoarthritis, and young, high-demand patients who are not a candidate for meniscal transplantation.

Meniscal root repair is contraindicated in: instances of advanced degenerative changes affecting the knee; uncorrected lower extremity malalignment; uncorrected ligamentous instability; inflammatory arthritis.

Causes

Meniscal root tears can be caused by:

• Sudden twist or quick turn during sports activity
• Heavy or awkward lifting
• Knee injury or trauma
• Degenerative changes due to aging

These are more common in patients in their 5th to 6th decades and females seem to be effected more than males. There is an association with elevated body mass index as well.

Diagnosis

A typical history for medial meniscal root tears is different from standard meniscal tears. The patient will often have a period of knee pain that seems to have come out of nowhere. The pain will be mild but nagging. Sometimes a patient will even present with an MRI that is read as “normal”, but in fact you can see that the meniscus is beginning to extrude.

After a period this will then yield to a brief moment, often something that seemed very minor, followed by severe pain and difficulty even bearing weight.

What is happening here, I suspect, is that with the sudden complete loss of the radial meniscal fibers the joint is suddenly overloaded. It is though, in that moment, the patient suddenly had no functional meniscus at all. Biomechanically this is exactly what has happened as the meniscus is extruded and loses all ability to function as a shock absorber. When this happens I like to proceed to surgery relatively soon if the meniscus is to be repaired.

Procedure

Meniscal root repair involves a surgical procedure where the torn meniscal root is reattached to its anchoring point in the knee. This is typically done using an arthroscopic technique, which involves small incisions and the use of a camera to guide the surgery.

From a technical perspective, if the tear has been long standing or there is significant extrusion of the meniscus Dr. Gilmer prefers to add an additional suture or centralization suture to help augment these tears.

These tears are more technically complex than standard meniscal repair and the rehab is similarly more challenging.

An example of a meniscal root repair using a technique very similar to Dr. Gilmer’s preferred technique is here

Post-Operative Care

Post-operatively, there is a period of limited weight-bearing and immobilization for the first 6 weeks. The knee is allowed to move 0-90 degrees in a brace but without putting weight on the leg. During this time our team utilizes blood flow restriction therapy and TENS or NMES (neuromuscular electrical stimulation) to reduce the atrophy that occurs during healing of the repair. Physical therapy is advised to regain knee strength and mobility for about 3 months postoperatively and then some patients will transition to a bridge program. Full return to sports activities is typically advised to wait until 6months post-op in my practice, depending on the individual case.

Risks and Complications

As with any knee surgery, possible risks include knee stiffness, infection, blood clots, nerve and blood vessel damage, and ligament injuries. Common side effects of meniscal root repair include joint pain, back pain, joint swelling, and joint effusion. Ultimately, if these repairs fail, or are avoided the alternative is partial knee replacement or UKA

Dr. Gilmer’s Take-

The idea of meniscal root repair is very compelling for a variety of reasons. Mostly if repaired acutely this can restore the shock absorbing function of the meniscus and prevent the development of early arthritis. It is a procedure that can greatly improve a patient's quality of life and overall knee function if successful. However, it requires a dedicated postoperative rehabilitation program and a thoughtful patient selection to ensure the best possible outcome. Some patients may ultimately do better, faster, with UKA, but because the trauma seems trivial it is often difficult to get buy in from patients who seemed to have just had a ‘simple meniscus tear’. We spend a lot of time emphasizing how different these are from the standard meniscal tear and why the treatment options are different.

Brian Gilmer, MD August 2023

Meniscal Root Tears : A single surgeon experience

Medial Meniscal Root Tears – A spectrum of disease

Despite being initially described in 1991 (1), when I exited training about 10 years ago, I had never seen, much less treated, a meniscal root tear. However, I am now certain that it was seeing me. What seemed like a relatively rare or obscure diagnosis is now one of the most commonly performed isolated meniscal repairs in my practice.

Unfortunately, recognition outside of the sports medicine and arthroscopic knee subspecialty remains lagging and these tears are often missed or present late. This is unfortunate given the poor prognosis when left untreated with reports of progression to total knee arthroplasty in 28% of cases within 3 years and 50% at 10 years. (2)

Root tears rapidly trigger a cascade of join degradation because they are biomechanically equivalent to total meniscectomy, result in meniscal extrusion, markedly decrease joint contact area, and are associated frequently with spontaneous insufficiency fracture of the knee (SIFK) and rapidly progressive cartilage loss.(3)

I remember a board review question from around 2014 on the topic of SONK, or spontaneous osteonecrosis of the knee. The giant bone bruises and severe pain that were the hallmark of the diagnosis have now been linked to the medial meniscal root tears in the vast majority of cases. It was a couple years into clinical practice when I met a middle aged female patient who had simply stepped down off a curb, felt a pop, and immediately had severe pain and was almost unable to walk. By this time, I was aware of the diagnosis and spent over an hour performing a transosseous meniscal root repair. In that first repair I learned several things that are helpful even now:

1. Pie crust the MCL immediately to open the working space. A recent study has even showed improved outcomes comparing a MCL released to non-released cohorts.
2. Use an arthroscopic wand to perform a reverse notchplasty removing the fibers of the inferior most parts of the PCL all the way back to the meniscal root made it much easier to insert the drill guide.
3. Using a small non absorbable 0 suture and creating a passing suture with a loop tied on the end makes it easier to pass through the thickened and often brittle posterior horn remnant. Once passed and retrieved a larger suture can be shuttled in to hold the repair
4. Pass the suture near the root posterior and closest to the free edge first, then pass the second suture closer to the free edge more peripherally towards the meniscal body
5. Set the drilling guide to a position a little steeper and start closer to the tubercle. Place the guide with the knee around 30 degrees with a valgus force, then slowly bring the knee to 90 degrees while keeping the guide in place.
6. Plan for the root tunnel to start on the tibia a bit closer to the tubercle and distal to where an ACL tunnel typically starts.

My early results were pretty good, but not perfect. I started to look for ways to improve these outcomes, and this led to looking for extrusion first, and looking for the bone bruise patterns in the periphery of the tibia instead of just on the femur. This would supplement the usual ghost sign on the more commonly viewed sagittal T2 images. I noticed that these patients with more extrusion tended to do less well clinically. The simplest way to note the amount of extrusion is to scroll through the coronal T2 images around the borders of the MCL and use the edge of a piece of paper covering any meniscus that falls outside the lateral edge of the tibial plateau and the femoral condyle. The amount of meniscus between those weight bearing surfaces gives you an idea of how much the meniscus is cushioning the articular surfaces.

In other cases, I would see patients with the classic pain pattern and presentation, but without the pop and sudden pain. These patients seemed to have extrusion but without root tear. Around the time that I was thinking about this chicken or the egg relationship, I came across the literature supporting the idea that extrusion is an early finding on a spectrum of disease which later concludes in full thickness root tear.(4)

And so, it seemed that both needed to be treated, especially when the pain was more peripheral (extrusion) than posterior (root). I was initially using an all-inside meniscal anchor at the junction of the posterior horn and mid body. I would pass the root sutures, traction them, and then place and tension an all-inside anchor to relieve some stress on the root sutures. I had no real data to support this, but it was a simple addition and used a well-accepted technique.

In fact, some authors have advocated for side to side suture repair of the root itself using allinside suture anchors. This as well is technically simpler and may have similar results according to some small series. (5). Personally, I have used this approach sparingly but it has been useful in cases of potential tunnel convergence as with multiligamentous knee injuries or when there is concomitant PCL reconstruction with a large tunnel that is near the typical transtibial tunnel location for the root repair.

Back to extrusion. I came across the concept of meniscal centralization in the Arthroscopy journal. It seemed like a very obvious deduction. Anchors placed on the edge of the tibial plateau, repairing the meniscotibial ligaments or repairing the meniscus to the plateau itself can reduce extrusion.

I added this to my practice first with root repair as an adjunct, but eventuallly in some select cases in isolation when there was clearly extrusion and bone edema near the insertion of the meniscus without root tear. Centralization is compelling because it potentially intervenes earlier in the disease process, prior to the progression to full thickness root repair. This can be a difficult clinical entity to diagnose as the MRI is frequently read as “normal” while the patient has all the characteristic history and exam findings of impending root repair. The biomechanical data for centralization have been encouraging(6). In 2024, the first (to my knowledge) clinical study was published (7) again with promising short term results.

I have performed centralization using a modification of the technique described by Krych (8) with 1-2 anchors placed at the junction of the posterior horn and body and repeated more anteriorly as needed with knotless suture anchors and a suture lasso. Unfortunately, I have had one case where an intraosseous cyst occurred around the anchor on repeat MRI and this remained symptomatic. In this case it was the more anterior of the two centralization anchors and the more posterior anchor did not have the same appearance. The cyst was symptomatic but the patient deferred from further treatment at time of this writing. Anecdotally, I have noticed prolonged pain at the anchor sites from meniscal centralization relative to root repair alone. The significance of these observations is still unknown.

An alternative technique involves repair of the meniscotibial ligaments through interlocking knotless all suture anchors that are placed extraarticularly. This may be easier and may keep the anchors from developing cysts since they are maintained outside of the joint and presumably synovial fluid would not leak into the subchondral space.

More controversy exists on the lateral side where a lateral root tear that maintains attachment to the PCL through the Wrisberg ligaments is not infrequently encountered with associated ACL injury. While some maintain that this may represent a normal morphological variant, or an incidental finding, I have rarely encountered this outside of the ACL injured knee. As a result I have tended to repair these using a transtibial pull out technique through a separate tunnel drilled at a higher angle than for the ACL reconstruction. This has not led to tunnel convergence with the ACL graft. There is biomechanical evidence to support that repair in this way reduces contact pressures much like the medial side and even reduces anterolateral rotatory instability.(9)

In summary, our understanding of meniscal root tears, both medial and lateral, has progressed tremendously there are a great many unknowns that remain. While centralization and meniscotibial ligament repair are controversial it is safe to say that we all should be vigilant in bringing attention to what has been called a “silent epidemic” in order to identify and treat these tears earlier before the development of arthrosis in the ipsilateral compartment.(10)

Citations

1. Pagnani MJ, Cooper DE, Warren RF: Extrusion of the medial meniscus. Arthroscopy 1991;7:297-300.
2. Allaire R, Muriuki M, Gilbertson L, Harner CD: Biomechanical consequences of a tear of the posterior root of the medial meniscus. Similar to total meniscectomy. J Bone Joint Surg Am 2008;90:1922-1931.
3. Banovetz MT, Roethke LC, Rodriguez AN, LaPrade RF. Meniscal Root Tears: A Decade of Research on their Relevant Anatomy, Biomechanics, Diagnosis, and Treatment. Arch Bone Jt Surg. 2022 May;10(5):366-380. doi: 10.22038/ABJS.2021.60054.2958. PMID: 35755791; PMCID: PMC9194705.
4. Krych AJ, LaPrade MD, Hevesi M, Rhodes NG, Johnson AC, Camp CL, Stuart MJ. Investigating the chronology of meniscus root tears: do medial meniscus posterior root tears cause extrusion or the other way around?. Orthopaedic Journal of Sports Medicine. 2020 Nov 3;8(11):2325967120961368.
5. Yoon KH, Lee W, Park JY. Outcomes of Arthroscopic All-Inside Repair Are Improved Compared to Transtibial Pull-Out Repair of Medial Meniscus Posterior Root Tears. Arthroscopy. 2023;39:1376-1383.
6. Kohno Y, Koga H, Ozeki N, Matsuda J, Mizuno M, Katano H, Sekiya I. Biomechanical analysis of a centralization procedure for extruded lateral meniscus after meniscectomy in porcine knee joints. Journal of Orthopaedic Research®. 2022 May;40(5):1097-103.
7. Krych AJ, Boos AM, Lamba A, Smith PA. Satisfactory Clinical Outcome, Complications, and Provisional Results of Meniscus Centralization with Medial Meniscus Root Repair for the Extruded Medial Meniscus at Mean 2-Year Follow-Up. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2024 May 1;40(5):1578-87.
8. Leafblad ND, Smith PA, Stuart MJ, Krych AJ. Arthroscopic centralization of the extruded medial meniscus. Arthroscopy Techniques. 2021 Jan 1;10(1):e43-8.
9. Krych AJ, Bernard CD, Kennedy NI, Tagliero AJ, Camp CL, Levy BA, Stuart MJ. Medial versus lateral meniscus root tears: is there a difference in injury presentation, treatment decisions, and surgical repair outcomes?. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2020 Apr 1;36(4):1135-41.
10. Cinque ME, Chahla J, Moatshe G, Faucett SC, Krych AJ, LaPrade RF. Meniscal root tears: a silent epidemic. British journal of sports medicine. 2018 Jul 1;52(13):872-6.

Brian Gilmer, MD is an orthopedic surgeon in Reno, NV and Mammoth Lakes, CA. This clinical editorial is meant to be only a cursory and incomplete overview and represent extrapolations from the known data regarding these topics. My comments do not presume to represent expert opinion but hopefully prompt further reading and consideration.

References

1. LaPrade, C. M., James, E. W., Cram, T. R., Feagin, J. A., Engebretsen, L., & LaPrade, R. F. (2015). Meniscal root tears: a classification system based on tear morphology. The American journal of sports medicine, 43(2), 363-369.
2. Feucht, M. J., Kühle, J., Bode, G., Mehl, J., Schmal, H., Südkamp, N. P., ... & Niemeyer, P. (2015). Arthroscopic transtibial pullout repair for posterior medial meniscus root tears: a systematic review of clinical, radiographic, and second-look arthroscopic results. Arthroscopy: The Journal of Arthroscopic & Related Surgery, 31(9), 1808-1816.
3. Chung, K. S., Ha, J. K., Yeom, C. H., Ra, H. J., Jang, H. S., Choi, S. H., & Kim, J. G. (2014). Comparison of clinical and radiologic results between partial meniscectomy and refixation of medial meniscus posterior root tears: a minimum 5-year follow-up. Arthroscopy: The Journal of Arthroscopic & Related Surgery, 30(1), 33-39.
4. Kim, J. H., Chung, J. H., Lee, D. H., Lee, Y. S., Kim, J. R., & Ryu, K. J. (2011). Arthroscopic suture anchor repair versus pullout suture repair in posterior root tear of the medial meniscus: a prospective comparison study. Arthroscopy: The Journal of Arthroscopic & Related Surgery, 27(12), 1644-1653.
5. Sonnery-Cottet, B., Conteduca, J., Thaunat, M., Gunepin, F. X., & Seil, R. (2014). Hidden lesions of the posterior horn of the medial meniscus: a systematic arthroscopic exploration of the concealed portion of the knee. The American journal of sports medicine, 42(4), 921-926.