Technique for Arthroscopic Transtibial Medial Meniscus Posterior Root Repair

Abstract

Background:

Medial meniscus posterior root tears (MMPRT) can lead to significant pain, functional limitations, and osteoarthritis (OA). Biomechanically, MMPRT has been shown to be equivalent to total meniscectomy in terms of peak contact pressure in the medial compartment. Transtibial repair of a meniscus root tear has also been shown to restore hoop stresses and reduced peak contact pressure to the normal intact state. Clinically, root repair was shown to reduce rates of OA progression and need for total knee arthroplasty when compared with nonoperative treatment or partial meniscectomy for MMPRT.

Indications:

Medial meniscus posterior root repair is indicated in patients with a symptomatic MMPRT who are appropriate surgical candidates: age ≤65 years, body mass index ≤40 kg/m², <5° varus alignment, no more than Kellgren-Lawrence grade 2 changes, and willing and able to undergo the demanding postoperative rehabilitation program.

Technique Description:

This surgical technique video demonstrates our preferred technique for arthroscopic transtibial medial meniscus posterior root repair using a case example in a commonly encountered patient. The repair is completed using a 3 simple suture triangle configuration with 2 tibial tunnels to create a broad footprint for healing.

Results:

There are a number of case series and comparative studies published with good clinical outcomes using similar transtibial medial meniscus posterior root repair techniques. In short-term follow-up of 18 patients at a mean of 10.5 months post-operatively, we have demonstrated improvements in pain and functional status with a 16.7% clinical failure rate and 11% rate of conversion to arthroplasty.

Discussion:

In this surgical technique video, we review the anatomy of the native medial meniscus posterior root and the biomechanical and clinical consequences of a MMPRT. We highlight important technique pearls and pitfalls to avoid failures and complications during the surgical demonstration. Finally, we review postoperative rehabilitation guidelines and clinical outcomes within the existing literature. In patients with MMPRT, transtibial repair provides a safe and reliable technique to achieve healing of the medial meniscus posterior root and return patients to full activities with reduced risk of OA progression.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This video describes our technique for arthroscopic transtibial medial meniscus posterior root repair.

Disclosures are shown here.

Medial meniscus posterior root tears can lead to significant impairment, and surgical treatment is often indicated to improve function and reduce the risk of osteoarthritis progression. This video will review the existing literature, present our preferred technique for arthroscopic meniscus root repair with a case presentation, and review published outcomes.

The anatomy of the medial meniscus posterior root attachment has been well described. ⁶ It is located 9.6 mm posterior and 0.7 mm lateral from the apex of the medial tibial eminence. ⁶

A medial meniscus root tear is defined as a soft tissue or bony avulsion or radial tear within 1 cm of the root attachment.^1,8 In a biomechanical study, a medial meniscus posterior root tear was equivalent to a total meniscectomy demonstrating a 25% increase in peak contact pressure. Performing a transtibial root repair restored peak contact pressure to normal. ¹

Our patient is a 50-year-old woman who developed posteromedial knee pain after a ground level fall. This was initially treated with a steroid injection and physical therapy, which provided short-term pain relief. She then developed worsening posteromedial knee pain and was referred to my office for evaluation. On my initial examination, she was noted to have a body mass index (BMI) of 30.8 kg/m². She had near full range of motion, with a moderate knee joint effusion and pain with provocative tests for a medial meniscus tear.

Weight bearing anteroposterior x-ray demonstrates mild degenerative changes with minimal medial joint space narrowing and small osteophytes formed. Full-length alignment x-rays demonstrate 2° of varus alignment in the left knee.

Rosenberg, lateral, and sunrise views similarly demonstrate minimal degenerative changes.

Coronal MRI of the left knee demonstrates the medial meniscus posterior root tear shown by the red arrow. In addition, there is about 2 mm of medial meniscus extrusion at the midbody. The medial compartment cartilage is thinned though appears overall intact.

Sagittal view of the MRI demonstrates absence of the posterior root attachment, also known as the “ghost sign.”

In assessing this case, the patient is a 50-year-old woman with a medial meniscus posterior root tear now about 12 weeks from her initial injury. She has mild degenerative changes, with Kellgren-Lawrence (KL) grade 2. She has a neutral mechanical axis with mild meniscal extrusion and is willing to undergo the rehabilitation protocol.

Surgery is indicated in patients with a medial meniscus posterior root tear who are appropriate surgical candidates, which, in general, includes patients who are <65 years of age, BMI <40 kg/m², mechanical axis within 5° of neutral, and KL grade 1 or 2 changes. ⁸ In addition, it is important for patients to be willing and able to undergo the rehabilitation protocol. Relative contraindications include patients with advanced age and significantly elevated BMI. In patients with varus malalignment >5°, you may consider a concomitant high tibial osteotomy. Advanced osteoarthritis, such as KL grades 3 or 4 or collapse of bone due to insufficiency fracture, are also contraindications. ⁸

Patient is positioned supine in a circumferential leg holder at the level of the tourniquet with the contralateral leg in a well-padded leg holder or stir-up, and the foot of the bed dropped to have full control of the operative limb. General anesthesia is used, and a pericapsular injection with primarily ropivacaine is used intraoperatively.

I prefer to place my medial portal low and just above the anterior horn of the meniscus to have an inline trajectory with the posterior root. In addition, I will pie-crust the medial collateral ligament (MCL) using a spinal needle at the femoral insertion to improve visualization and access to the medial compartment. Using a probe, we have identified a posterior root tear. I will usually shrink the synovium over the posterior cruciate ligament, and perform a reverse notchplasty as needed.

I will now perform a Gillquist maneuver to visualize the posterior medial meniscus root, and probing here we can see the posterior root is completely detached. In this case, there is still a remnant of the root attachment site, which will help guide our repair. I will use the electrocautery to shrink these soft tissues and then a ring curette to create a bleeding bone bed for healing of the meniscus at its attachment site. I will bring in the shaver to finish removing the soft tissues. In this case, I made a larger bleeding bed and went slightly medial to have a larger area for meniscus-to-bone healing.

Using a grasper, I will confirm that the meniscus will reduce to the anatomic foot print. I will then use a self-capture suture passing device (Knee Scorpion; Arthrex; Naples, FL) to place simple sutures with 0.9-mm Suture Tape (Arthrex) in a triangle configuration. Suture management is important during these steps, and I will make sure to take the inferior limbs together and superior limbs together for later passing through the tibial tunnels. In cases where the quality of meniscus tissue is poor or if we experience pull out of the sutures, I will use a looped suture, such as a FiberLink (Arthrex) and place a luggage tag suture around the meniscus with the simple sutures on the medial side of this luggage tag as a rip stop backup.

I will then use the root repair drill guide (Smith & Nephew, Waltham, MA), which uses a cannulated drill bit. I prefer a 2-tunnel technique to allow for a larger surface area across the meniscus attachment site and to compress the meniscus tissue down to the bone with the simple sutures. The first tunnel is placed slightly posterior and medial to the native attachment site. The drill guide is then removed. The tunnel is completed to confirm appropriate position. A nice trick here is to use bone wax over the end of the cannula to prevent any further fluid leak and to aid in suture passage.

Then using the 5-mm offset guide, I will place the second tibial tunnel slightly anterior and lateral to the first tunnel within the anatomic footprint. Here, the second cannulated drill bit is drilled into position, and you can see this here with the arthroscope at the anatomic footprint. This appears to be in an appropriate position, and once we are happy with our tunnels, we will proceed with suture passage. A spinal needle is then used to remove the bone wax, and a passing suture is sent into the first cannula. The inferior sutures are then grasped, and the arthroscopic grasper is passed into the knee while holding the sutures to avoid any soft tissue bridge. The passing suture is then brought out through the same portal and the suture limbs are shuttled through the tibial tunnel.

Suture management is important at this point to ensure there is no crossing of the suture limbs. The cannula is then removed with pliers. Similarly, the passing suture is used in the second tibial tunnel. This will be pulled out through the medial portal and used to shuttle the superior limbs of the sutures through our second tunnel. Again, important to monitor for crossing of the sutures and make sure that they are sliding easily because they can get caught on the sharp edge of the cannula. At this point, I will assess the tension on the repair by taking the knee through a range of motion while holding the sutures tensioned at the anteromedial tibia. I typically will tie the sutures down with the knee at about 30° to 45° of flexion.

The sutures limbs are tied to each other over a bone bridge to complete the repair of the meniscus while visualizing with the arthroscope to ensure they are not overtensioned. I will tie the lateral most sutures first, and the third suture is used as a backup over the top of the repair. It is important to not overtension this more medial suture. Assessing the repair demonstrates compression of the root across the anatomic foot print, and it appears to be appropriately tensioned.

We will then proceed with backup fixation of the sutures into a suture anchor (4.75-mm SwiveLock Anchor; Arthrex). This is typically hard cortical bone so I will drill and then tap for the anchor. I will visualize with the arthroscope while placing the anchor to ensure the sutures are not overtensioned. We will then assess the final repair by probing, and it appears to be appropriately tensioned.

This is a summary of the technique pearls and pitfalls for various steps of the procedure. It is important to reduce the meniscus to its anatomic position, and a meniscocapsular release can be performed if needed. Pie-crusting of the MCL and reverse notchplasty are often required to allow adequate visualization and access to the medial compartment. Use of a drill guide is important for accurate tunnel placement and to avoid overdrilling and risk of iatrogenic neurovascular injury. In patients with softer bone, the sutures can be tied over a button to ensure they will not cut through the bone and loosen over time.

When we discuss assessing the tension on the repair through a range of motion, this was an interesting article recently published in Japan measuring the amount of suture translation during knee flexion and found there was on average 3.6 mm of translation going from full extension to 90° of flexion. ¹⁰ Some authors advocate for fixation at 90°, which may lead to loosening as the knee is extended. Others advocate for fixation in full extension or around 30° of flexion, which may be too tight when flexing the knee. ¹⁰ I will always hold tension on my sutures with the knee in full extension and then flex to 90° to assess how tight the repair will be. Often, I will fix the sutures with the knee at about 30° to 45° of flexion.

Here is a summary of the potential complications with this technique, and tips on how to avoid and treat these potential complications.

This is a summary of the postoperative protocol with the full protocol available online https://medicine.osu.edu/-/media/files/medicine/departments/sports-medicine/advanced-meniscus-repairfinal.pdf?la=en&hash=D49F902356C1C72596F229791074195F84CF8453.

Here is a summary of the return-to-sport criteria that is coordinated with physical therapy.

This is one of the first studies to report clinical outcomes in a group of 20 patients with a minimum follow-up of 2 years. ⁹ Ten knees underwent second-look arthroscopy at a mean of 14 months, which demonstrated complete healing of the meniscus root repair. They had 1 retear, which underwent revision repair and did well after 6 months. Only 1 patient had progression of knee OA from KL grade 2 to grade 3. ⁹

In a systematic review published this year of 994 patients from 28 studies, they reported significantly improved clinical outcomes. ² The radiographic progression was reported in 11 studies, and 49% of patients had at least 1 KL grade of progression at a mean follow-up of 4 years. Only 11 of the 232 patients (5%) progressed to total knee arthroplasty at a mean follow-up of 76 months. The healing status of the meniscus was evaluated in 422 patients by second-look arthroscopy in 11 studies, and MRI in 8 studies. They reported 58% with complete healing, 36% partial healing, and a 7% retear rate or failure at a mean follow-up of 38.1 months. ²

I have been using this technique since August 2020 and have performed in 27 patients with an isolated medial meniscus root repair. Eighteen of those patients have a minimum 6 months of follow-up and are considered here. These patients have a mean age of 56.4 years with minimal arthritis based on the KL scale. Postoperatively, I had 4 patients with progression of their arthritis by 1 KL grade on follow-up x-rays at 6 months or 1 year. Three patients were considered failures for a 16.7% failure rate during this short-term follow-up. Single assessment numeric evaluation demonstrated improvement over baseline at 6 months and 1 year postoperatively.

In conclusion, transtibial meniscus root repair leads to improved functional outcomes and lower rates of osteoarthritis progression and total knee arthroplasty versus meniscectomy or nonoperative treatment of medial meniscus posterior root tears in appropriately selected patients.

The presented technique uses biomechanical principles to maximize the surface area for meniscus to bone healing using a 2-tunnel, simple suture configuration. Further biomechanical and comparative clinical studies are needed to determine the optimal repair constructs.

Here are our references, and thank you for watching our video.