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A walkthrough of the surgical repair of meniscal root tears
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Meniscus posterior horn root tears with associated extrusion have generated considerable interest since their initial description by Pagnani and colleagues. In 2008, Allaire and colleagues demonstrated a medial meniscus posterior horn root avulsion is biomechanically equivalent to a complete meniscectomy due to the abnormally high peak tibiofemoral contact pressures.
Several other studies have since associated meniscal extrusion with progressive degenerative osteochondral damage. Loss of the root attachment impairs the ability of the meniscus to resist hoop stress when the tibiofemoral joint is loaded. This produces increased joint contact pressure and leads to rapid articular cartilage damage, subchondral bone edema and sometimes collapse, previously referred to as “spontaneous osteonecrosis.”
Types of root tears
Images: Krych AJ
There are two types of meniscal root tears. The first is a traumatic tear that typically occurs in younger patients in association with a knee ligament injury. The second is a degenerative tear resulting from a low-energy injury mechanism in older patients, such as getting up from a deep-seated position. The traumatic tears likely represent true avulsions of the posterior horn root attachment of the medial or lateral meniscus (Figure 1). These tears should be repaired in all cases at the time of knee ligament reconstruction.
The degenerative tears are usually full-thickness radial tears near the root junction, but not a true avulsion of the meniscal attachment to bone (Figure 2). These tears can be associated with early knee arthritis. Indications for repair in this setting are evolving and the optimal candidate has not yet been defined. Contraindications to meniscus root repair include subchondral bone collapse, radiographic joint space narrowing of the affected compartment, varus or valgus malalignment, and obesity. Meniscal repair in this setting is unlikely to heal or restore function.
In two comparison studies, the results of root repair were superior to nonoperative treatment for selected patients. Ahn and colleagues compared 25 medial meniscal root repairs to 13 patients without surgery and found the repair group had better subjective scores, activity scores and knee function scores. However, the repair group knees with greater than 5° varus malalignment or greater than grade 3 cartilage changes at the time of arthroscopy did not have better results. The authors concluded repair alone is not beneficial in the setting of varus malalignment or grade 3 degenerative cartilage changes.
Arthroscopic view of flip cutter in root footprint remnant is shown.
Arthroscopic view of shuttling suture through tibial socket is shown.
Chung and colleagues compared 20 partial meniscectomy patients to 37 root repair patients with a minimum 5-year follow-up. The repair group had superior subjective knee rating and knee function scores, as well as less radiographic progression of arthritis. In addition, none of the repair patients underwent subsequent knee arthroplasty compared to 35% of the debridement group. The authors concluded repair is more effective than debridement.
Repair technique
Two repair techniques have been described for meniscus posterior horn root repair: suture anchors (direct fixation) and transosseous sutures (indirect fixation). The direct fixation procedure is technically demanding because the sutures are inserted through a posterior portal with a curved suture-shuttling device that may be difficult to manipulate in the knee joint. A recent study evaluating the strengths of various suture techniques found a locking loop provides significantly higher load-to-failure than other suture configurations.
Our preferred technique for meniscus posterior horn root repair uses a suture-passing device to create locking loop stitches, which are passed through the tibia, tensioned and fixed on the anterior cortex. This method is safe, efficient and reproducible and creates a biomechanically strong repair without the need for a posterior portal.
Standard knee arthroscopy portals are created, including an ipsilateral portal made under direct visualization to ensure access to the posterior meniscal root. The posterior horn attachment is inspected and palpated with a probe. In order to obtain adequate visualization of a medial meniscal tear and adequate space to introduce instrumentation, the medial collateral ligament (MCL) may need to be lengthened. This is accomplished by percutaneous fenestration of the proximal MCL using a spinal needle while applying valgus force to the knee. In addition, a reverse notchplasty may be performed by removing a small amount of bone from the wall of the notch and shaving down the medial tibial spine. Finally, removal of synovium from the PCL can be beneficial.
Once the working space is optimized, a tibial socket is created at the meniscal root attachment. This is accomplished using an ACL tibial tunnel guide placed through the ipsilateral portal. Once the guide is positioned intra-articularly at the center of the meniscal root footprint, a 6-mm FlipCutter (Arthrex) is introduced into the joint through a small incision on the proximal-medial tibia. The FlipCutter is deployed and a 6-mm diameter socket is created to a depth of 10 mm (Figure 3). The device is then removed from the joint and replaced by a FiberStick (Arthrex), which is used for later passage of the meniscus sutures through the tibia (Figure 4). The FiberStick passing suture is retrieved through the contralateral viewing portal to avoid tangling during suture passage into the meniscus.
Arthroscopic view of self-retrieving suture passing device is shown.
Arthroscopic view of a locking loop suture is shown.
A cannula is placed through the ipsilateral working portal to prevent a soft-tissue bridge and aid in suture management. A free No. 0 non-absorbable suture is then passed through the torn meniscus in a locking loop configuration using a self-retrieving suture passing device (NovoStitch; Ceterix Orthopaedics or the Knee Scorpion, Arthrex) (Figure 5). Locking loop sutures are placed (Figure 6) along with a simple “leader” stitch close to the socket. This stitch will lead the meniscus tissue into the socket during tensioning. The sutures should then be individually tightened to remove slack. Next, all sutures are shuttled through the tibial socket using the previously placed passing suture. The knee is cycled to remove the creep from the repair construct.
The leader stitch is tensioned first, followed by the other locking sutures to reduce the meniscus back to the root attachment (Figure 7). If the meniscal root is not adequately reduced, the bone and cartilage in contact with the meniscus can be decorticated to allow for biologic healing with the suture fixation remaining in the anatomic socket. Tibial fixation is obtained with a 5.5-mm SwiveLock (Arthrex) anchor placed into the proximal-medial tibia through the previous incision.
Postoperative management
During the first 4 weeks after surgery, full extension toe-touch weight-bearing in a brace and knee flexion to 90° are allowed. After 4 weeks, the brace is discontinued and the patient may begin full weight-bearing and full knee range of motion as tolerated. Knee loading at flexion angles greater than 90° is not permitted until 4 months postoperatively.
The results of meniscus posterior root repair are good in selected patients, though longer-term follow-up studies are needed to assess the potential chondroprotective effect. Repair is advised when possible, as patients treated without surgery or with arthroscopic debridement have been shown to fare poorly. Advantages of the presented technique include a biomechanically strong suture construct, no need for a posterior portal and instrumentation designed specifically for the knee. This represents another method of meniscal repair and preservation, which are vital to normal knee function.
- References:
- Ahn JH,et al. Arch Orthop Trauma Surg. 2015;doi:10.1007/s00402-015-2269-8.
- Allaire R, et al. J Bone Joint Surg Am. 2008;doi:10.2106/JBJS.G.00748.
- Blackman AJ, et al. Arthrosc Tech. 2014;doi:10.1016/j.eats.2014.07.006.
- Chung KS, et al. Arthroscopy. 2015;doi:10.1016/j.arthro.2015.03.035
- Feucht MJ, et al. Arthroscopy. 2015;doi:10.1016/j.arthro.2015.03.022.
- Hein CN, et al. Knee. 2011;doi:10.1016/j.knee.2010.04.006.
- Mitchell R, et al. Arthroscopy. 2016;doi:10.1016/j.arthro.2015.07.013.
- Pagnani MJ, et al. Arthroscopy. 1991;7(3):297-300;PMID:1750940.
- For more information:
- Aaron J. Krych, MD, and Michael J. Stuart, MD, can be reached at Mayo Clinic Department of Orthopedic Surgery and Sports Medicine, 200 First St. SW, Rochester, MN 55905; Krych email: krych.aaron@mayo.edu; Stuart email: stuart.michael@mayo.edu.
Disclosures: Krych reports he is a paid consultant for Arthrex and receives research support from Ceterix Orthopedics. Stuart reports he is a paid consultant for and receives royalties from Arthrex.