Meniscal Root Repair

1. What is a meniscus root?

The meniscus root is where the meniscus attaches to bone. The meniscus root attachment is important because if the meniscus becomes detached, it can “squirt” out of the joint, called extrusion, which can lead to the meniscus not being functional. Meniscus root tears are a particularly troublesome type of meniscus tear, because a failure to treat them can often result in the rapid development of osteoarthritis. In particular, it has been found that one of the most common reasons why younger patients need total knee replacements is because of a neglected or undiagnosed meniscus root tear leading to the development of osteoarthritis.

2. What is a meniscus root repair?

A meniscus root repair involves reattaching the meniscus back to bone where it has been torn. The steps in a meniscus root repair are very intricate and our biomechanical studies have validated that the steps are essential. First, one needs to ensure that the meniscus root is repairable and that there is not too much arthritis on that affected portion of the joint such that a meniscus root repair would not be recommended. If a patient does have a meniscus root tear and the cartilage in that same compartment is still relatively good or normal, a meniscus root repair would be indicated. Often, when a meniscus root is torn, it will retract in the joint and become stuck in place.  If one does a meniscus root repair in that extruded position, the chance of a meniscus root repair working over the long term is very minimal. Therefore, most meniscus root tears need to have the scar tissue released so the meniscus can be pulled back into the joint. The second step is to prepare a bony bed where the meniscus repair will be performed. This is called decortication of the medial tibial plateau (for a medial meniscus root repair).  These two steps are considered to be the two main preparation steps, where the release of adhesions to be able to allow the meniscus to be pulled back in the joint and also decortication of bone to prepare a bony bed to repair the meniscus back to the tibia. The next steps involve placing self-capture sutures into the end of the meniscus root and then drilling cannulas into the area that was decorticated such that the sutures placed into the meniscus can be shuttled down the cannulas and then tied over the tibia.

The first step is usually to use especially designed cannulas and guides to drill up into the area that was decorticated. We recommend the use of 2 cannulas such that the meniscus can be pulled down over a broader area and have a better chance of healing to the bone. This step involves making a surgical incision or extending a previous surgical incision (such as with an ACL reconstruction) and ensuring that one is dissected down directly to bone. A surgical guide can then be placed in a drill tip where the cannula around it is placed into the area of the decorticated bone. The drill tip can then be pulled out, leaving the cannula in place, which allows one to place a passing stich up it to subsequently shuttle sutures down the tibial tunnel.

The next step involves using a self-capture device to place either sutures or tape into the substance of the meniscus body. We currently use UltraTape to do this. Often, a patient will be placed into an unloader brace if they are bowlegged to take some of the stress off the healing repair.  In addition, because of studies from our biomechanical studies showing significant stress on the meniscus with deep flexion, as well as the fact that many meniscus root tears occur with deep flexion, we have patients avoid squatting, squatting and lifting and sitting cross-legged (which puts extra stress on a root repair) for a minimum of 4 months postoperatively to maximize the healing potential. In general, patients have to develop good quadriceps strength to allow for maximum absorption with activities prior to returning back to any significant hiking, jogging or running activities. It is felt that most meniscus root tear repairs are sufficiently healed to start these activities between 5 and 7 months postoperatively.

3. Meniscus root tear versus ACL

An ACL tear most commonly occurs from a turning, twisting, or deceleration mechanism in a noncontact mode.  Meniscus root tears usually occur in patients with deep flexion such as skiers, or home gardeners, plumbers, or carpet layers or people doing similar activities.  An ACL tear commonly has a pop on the outside of the knee, whereas a patient who has meniscus root tear commonly feels a pop in the back of the knee.

It is important to recognize that most patients who sustain isolated meniscus root tears happen with a medial meniscus root attachment.  Patients who have an ACL tear have a 10% chance of having a lateral meniscus root tear.  These are totally different.  Lateral meniscus root tears can lead to arthritis, but they also result in the ACL being a little looser and the clunk that comes with an ACL tear (pivot shift) being more unstable.  Thus, when one does sustain a lateral meniscus root tear with an ACL tear, consideration should be given to having a concurrent lateral meniscus root repair so the ACL graft does not stretch out.

4. What is the success rate for a meniscus root repair?

The general published success rate for a meniscus root repair is between 80% and 85%.  There are many factors that go into this, including a patient’s weight, with overweight patients putting more stress on the meniscus root tear, one’s alignment, where one being bowlegged with a medial meniscus root repair putting extra stress on the repair, and also the amount of underlying arthritis present prior to the root repair. If one has fairly normal cartilage of that side, the success rate is going to be better than those patients that have mild to moderate chondromalacia (arthritis) of the same compartment as the root repair.  In addition, the other factor is if the meniscus was released significantly enough from scar tissue to pull it back into the joint. A meniscus that still has extrusion present also does not function as well over the long term. While there are many factors that can go into extrusion, a maximum attempt should be made by the surgeon to try to pull the meniscus back in the joint to give the meniscus the best chance to function as a shock absorber after it heals.

5. What is the most common meniscus root repair technique?

The most common root repair technique is called a transtibial technique. In this technique, sutures are placed into the torn meniscus root and then shuttled down tunnels in the tibia to tie the repair into place. There are some isolated reports of using suture anchors to repair a meniscus root repair, but this area of the knee is very difficult to access and the suture anchors can leave large knots which could subsequently interfere with the cartilage surfaces in the knee. Therefore, the transtibial meniscus root repair technique is by far the most common procedure that is performed. There are 2 main variants of the transtibial root repair technique. These include 1-tunnel and 2-tunnel techniques. In our hands, because we have performed many second look arthroscopies, we have found that the 2-tunnel technique allows for a broader surface area of the meniscus against the decorticated bone and seems to allow for a more solid and secure repair.

6. When should one consider a root repair versus a meniscectomy?

Historically, most root tears were treated with meniscectomies because the importance of the meniscus root as a shock absorber was not well known. It has now been demonstrated that the results of meniscectomies are almost the same as not treating the meniscus root tear at all with a large number of patients within 5 years proceeding to needing a total knee arthroplasty. Therefore, it is strongly recommended to proceed with a meniscus root repair whenever possible, with patients up to the age of 70 being reported as having excellent return of function. The most important aspect to assess when one is looking at a root repair is to ensure that one’s cartilage surfaces are still fairly normal.  If one does have quite a bit of arthritis of the same compartment, which we would call Kellgren-Lawrence grades 3 or 4, in most circumstances, other than possibly in very young patients, a root repair would generally not be indicated.

7. What does an MRI look like after a meniscus root repair?

It can be very difficult to interpret an MRI after a meniscus root repair.  In general, one can follow the small tunnels from the transtibial technique up to where the root attachment should be. If there is tissue there, it usually means that the meniscus root repair has healed down to bone. The other aspect that needs to be evaluated is the amount of extrusion of the meniscus.  If the meniscus is extruded, the patient may not be having a restoration of their shock-absorbing capacity of the meniscus. Other factors can also be present with extrusion, including the progression of arthritis which can cause a well-done meniscus repair to extrude outside the joint.

8. What is a posteromedial meniscus root repair?

The back attachment of the medial meniscus, called a posterior horn attachment, is the most common location for meniscus root tears to occur. Most root tears involve either a direct tear of the meniscus off bone or a split of the meniscus within 1 cm of the root attachment. These “radial root tears” are equivalent to a meniscus root tear. Posterior horn medial meniscus root tears have been particularly noted to be a problem with a large number of patients developing arthritis rather quickly. Therefore, the patient should be worked up in a timely fashion when they do have a posterior horn medial meniscus root tear to determine if they are a candidate for a posterior horn medial meniscus transtibial root repair.

9. What is the Smith & Nephew meniscus root repair technique?

The Smith & Nephew root repair technique involves specific devices which can lower one’s surgical time to perform a meniscus root repair.  One of the main portions of the system is a guide that can be placed inside the joint that fits around the tibial eminences and allows the surgeon to place the tip of the guide right at the area that has been decorticated of bone, where one wants to perform the root repair tunnel. The system also involves a drill with a cannula whereby one can drill through the tibial guide, see the drill bit come out inside the knee, and then pull the drill bit out and leave the cannula in place. This technique allows one to place passing stiches up the cannula, which has significantly decreased the operative time. When one drills a tunnel and tries to place stitches up a tunnel without a cannula in place, it can be extremely technically challenging. Two cannulas are subsequently placed into the area of bone that was decorticated to allow for the transtibial 2-tunnel technique to be performed.  The next portion of the Smith & Nephew root repair device is a mini First-Pass device. Currently, there are mini First-Pass devices that curve to the right and the left, which allows increased access to a root tear, especially since most root tears tend to squirt to the back part of the joint and can be more difficult to access with a straight biter. The mini First-Pass device allows placement of either a suture or an UltraTape through the substance of the meniscus, capturing the end of the stitch as it is placed through the meniscus and then it can be pulled out of the joint.

These UltraTape or sutures can then ultimately be shuttled down the cannulas and then tied over a metal button on the front part of the tibia. This technique allows for the meniscus to be pulled down into a broad surface area, maximizing its chance for biologic healing.

10. What is the “LaPrade technique” for meniscus root repairs?

Because this is a frequent question posed on Google, I will try to be modest in answering this. We recognized that meniscus root tears were a problem over 10 years ago and set out to perform a comprehensive research program to help us figure out how to diagnose the problem, where to place the meniscus repair, and how best to fix the meniscus tear to allow for maximal healing capability. First, we performed quantitative anatomy studies, which allowed us to see exactly where a meniscus root tear should be reattached. Next, we performed biomechanical studies to show the effects of varying sizes of radial meniscus root tears, validating that a meniscus root tear within a centimeter of its attachment site functions as a meniscus root tear and can be treated the same. In addition, we looked at varying suture techniques through the meniscus, including 2 simple sutures, as well as other configurations of meniscus suture techniques, which are more complex. We validated that the 2 simple suture technique had the least amount of loosening over time, but the other techniques were  stronger. However, we felt that with a 6-week period of being nonweightbearing important for all meniscus root tears, that the 2 simple suture technique was valid. I also found that there were patients being referred to me who had meniscus root repairs that were done well, but the meniscus was not pulled back in the joint and these patients continued to have pain. When I went in arthroscopically and thoroughly released the meniscus, pulling it back into an anatomic position and revising the repair; all of these patients seemed to have much improved pain relief. Therefore, we found that non-anatomic meniscus root tear repairs were not successful. Therefore, we then looked at surgical techniques and due to the fact that we had multiple second look arthroscopies after bone grafting for ACL reconstructions with meniscus root tears, that the 1-tunnel technique had more of a “spot welding” healing of the meniscus to bone whereas the 2-tunnel meniscus root repair technique had a much better healing surface of the meniscus to bone.

Therefore, our surgical technique, using specific guides to avoid the eminences to ensure that one can place the guide exactly where one wants to have a cannula come out in the joint, using cannulas to allow for placement of passing sutures quickly and efficiently, having 2 separate cannulas with 2 separate tunnels for the meniscus repair, releasing the meniscus thoroughly to pull it back in the joint so it functions most effectively, and then having self-capture suture devices, which can place suture or tape into the meniscus substance, shuttle them down the tibia, and then tie them over a metal button on the tibia. During our biomechanical testing, we found that if we tied the sutures directly over bone, with cyclic loading, the sutures would cut into the bone and the repair would become loose over time. Therefore, we strongly advocate using a button to fix the meniscus sutures or tape on the tibia to minimize the chance of loosening over time.

We have published and validated our results in the peer-reviewed literature, which was at the time the largest series of meniscus root repairs reported. We found that the technique was very successful at restoring function to patients and significantly reducing their pain.

11. What is the age that one should look at for a meniscus root repair?

One should not look at age as a factor for meniscus root repairs. The most important thing as one gets older is the quality of the cartilage present. I have successfully repaired meniscus root tears in patients that were 70 and 71 years old respectively and they are some of my happiest patients.  One patient was noted to have an insufficiency fracture and spontaneous osteonecrosis of the knee (SONK) as part of the root tear and came in in a wheelchair and she has had  6 years of successful return to activities after her meniscus root repair, including hiking and cycling. In addition, there is no low age for meniscus repairs, with some root repairs being done in patients as young as 6 or 7 years old. In particular, these younger patients have to look at a meniscus root repair as soon as possible to ensure that they don’t develop arthritis.

12. What is a meniscus root bony avulsion repair?

In younger patients, meniscus root tears often occur with a piece of bone being avulsed off the tibia. In radiologic terms, this is called a “bony ossicle.” The technique for a repair for a bony avulsion, called a type 5 meniscus root tear, is similar to the other techniques other than it should have the bone piece shaved down and cleaned off such that it can be pulled back into the area where it had been avulsed from. Placing sutures or UltraTape on each side of the tear and pulling it down into tunnels should be a safe and reliable method for a bony avulsion root repair. In patients who have open growth plates, consideration may be necessary to either plan to remove the sutures after the meniscus root repair heals or to consider placing the tunnels and suture repair above the growth plate such that is does not cross the growth plate and have a theoretical chance of causing a growth plate arrest.

13. What is a lateral meniscus root tear?

A lateral meniscus root tear involves a tear of the meniscus either at or close to the root attachment in the back part of the lateral meniscus. Historically, these root tears are often treated with benign neglect and either ignored or trimmed out. Unfortunately, as we have developed more scientific evidence for this, including several studies in my lab, we found that the lateral meniscus root  is extremely important to both prevent the development of osteoarthritis over time and also to protect a concurrent ACL reconstruction graft.  This is because a lack of meniscus attachment at the root causes extra stress to be placed on an ACL graft and it can also result in the patient having more instability, both with anterior tibial translation, and with twisting and turning activities during the pivot shift, when there is a concurrent lateral meniscus root tear.

In particular, it is now recognized that the incidence of lateral meniscus root tears with an ACL tear is between 8% to 12%. Therefore, any surgeon who performs ACL reconstruction should be well versed in performing a lateral meniscus root repair.  If the lateral meniscus root tear is not repaired at the same time as an ACL reconstruction, it is now recognized that this could lead to ACL graft failure or loosening over time. Therefore, a lateral meniscus root repair can be an essential portion of a surgery to address the secondary restrains for a concurrent ACL reconstruction procedure.

14. What is the weightbearing program after a meniscus root repair?

In general, almost all meniscus root tears require a 6-week period of being nonweightbearing to maximize the healing potential. Many surgeons will tie the meniscus root repair with the knee bent, so that one can start motion right after surgery and not have to worry about the meniscus root repair being stretched out. Early weightbearing has been found to be the cause of meniscus root repair failure, and this has been validated by our colleagues In general, almost all meniscus root tears require a 6-week period of being nonweightbearing to maximize the healing potential. Many surgeons will tie the meniscus root repair with the knee bent, so that one can start motion right after surgery and not have to worry about the meniscus root repair being stretched out. Early weightbearing has been found to be the cause of meniscus root repair failure, and this has been validated by our colleagues

15. What are some of the complications that can occur after a meniscus root repair?

The most common complication after a meniscus root repair is a re-tear. This can occur in up to 20% of patients, even in the best of circumstances. This is probably due to many factors, including the chronicity of the tear, the quality of the tissue, if the meniscus was released from scar tissue and pulled back in the joint, one’s age, one’s weight, and one’s alignment.  Other complications can include a blood clot, which is usually treated preemptively with some type of blood thinner, and irritation around the surgical button and/or surgical knot from the meniscus root tear.  Most patients will also have some numbness around the surgical incision, but this is not a true complication and is anticipated with any type of surgical incision.

16. Where does one usually have pain with a meniscus root tear?

Most patients will have pain with squatting and deep knee flexion with a root tear because a meniscus root tear occurs in the back of the knee. More diffuse pain over the inside of the knee which becomes progressive over time can be particular ominous because this may mean that the cartilage is wearing out fast or that one has an insufficiency fracture or spontaneous osteonecrosis of the knee, occurring due to the fact that the meniscus is such an important shock absorber. Many patients do not have significant joint line pain like a typical meniscus tear, so having a patient stand up and squat down is often performed during the clinical exam to validate that the patient may have a meniscus root tear. Many patients who do have a meniscus root tear note that they feel a pop in the back of the knee when they are doing squatting activities, such as cleaning floors, gardening, placing down carpet or plumbing. This mechanism of injury and the description of a pop is the classic description of one who has a meniscus root tear occur.

17. What can be present if one has pain after a meniscus root repair?

There can be many factors which can potentially cause pain after a meniscus root repair. One of the most common is in patients who may have some underlying arthritis and the arthritis is causing the pain or the arthritis has progressed further after the meniscus root repair. This usually presents with pain along the inside or medial portion of the joint and with swelling with activities. This is because the signs of arthritis are usually pain and swelling with activities. Deconditioning of one’s quadriceps muscles can also cause similar symptoms, so it is important to determine if one has any atrophy of their thigh muscles, usually measured as the thigh circumference 15 cm above the patella and compared to the opposite leg. Other sources of pain can include scarring within the joint that occurs as a normal part of a surgical procedure, or pain from other pathology and joint, such as arthritis under the kneecap.  In general, in our practice, most patients who do have pain after a meniscus root repair fit into this category. While there are a small number of patients who do have their meniscus root re-tear, this has been nowhere near as common as the other sources noted above.

18. What can be done if a meniscus root repair fails?

In determining if one can have a revision root repair, one needs to determine the cause of the failure as well as the amount of underlying arthritis. If the patient has or has developed significant arthritis, which is usually designated at Kellgren-Lawrence grades 3 or 4, it is felt that a revision root repair may not be indicated. However, if the meniscus re-tore or is placed into a non-anatomic position and one’s cartilage surfaces are still fairly intact, an attempt at a revision repair should be made. In particular, making sure the meniscus has a thorough release from scar tissue and making sure that one’s sutures or UltraTape are placed into the best substance possible for the meniscus root repair, are important considerations to maximize the chance of healing of the revision root repair procedure.

19. What is an “iatrogenic” meniscus root tear?

An iatrogenic meniscus root tear means that a tunnel was drilled for an ACL or PCL reconstruction and hit the meniscus root and detached it from bone.  Iatrogenic meniscus root tears have been described for all 4 meniscal attachments in the knee. We have published on several of these, noting that a PCL tunnel which is placed too close to the joint can detach the posterior horn of the medial meniscus and lead to the development of arthritis of the medial compartment. Being aware of the location of the meniscal attachments at the time of ACL and PCL surgeries is essential to minimize the chance of an iatrogenic root tear.

20. What are the why, when, and how’s for a meniscus root repair?

The why answer is that the meniscus root is an important stabilizer to the meniscus to ensure that it can function as effectively as possible as a shock absorber. When the meniscus root becomes detached, the meniscus can extrude out of the joint and lead to effectively having no functional meniscus. Therefore, one should attempt a meniscus root repair whenever possible in most patients up to age 70.  In terms of when, one should plan to perform a meniscus root repair as soon as it is diagnosed as long as one’s articular cartilage is still fairly intact. If one has too much arthritis, then the chance of a meniscus root repair helping one to slow down the progression of arthritis is probably not worth having the meniscus root repaired. Therefore, addressing a meniscus root tear prior to the development of osteoarthritis would be indicated. In terms of how, the transtibial technique has been felt to be the most effective way to pull the meniscus root back to its normal attachment site. We use the 2-tunnel technique to maximize biologic healing of the meniscus down to a broad surface. Using specific guides to ensure that one can place tunnels in the anatomic position and using self-capture devices, which have been devised to be small enough to not scuff up the cartilage, are some of the best means to perform a transtibial meniscus root repair with self-capture devices.