Tears of the anterior cruciate ligament or ACL have become commonplace on the ball fields across the world. ACL injuries are usually treated with a reconstruction or a replacement of the torn tendon. Should we be repairing your ACL tear instead of replacing it with a graft?
Whether it is due to poor training, poor preparation, early single sports specialization, or just plain bad luck, the literature, and our experience will tell you that ACL injuries are increasingly more common. Once an ACL tears the athlete is looking at a long rehabilitation, a 25% chance of a re-injury, and only a modest chance of returning to their prior activities. Unfortunately, the athlete is also looking a good chance of developing arthritis down the road at a relatively young age. We are not exactly sure why the risk of developing arthritis is so high with our current reconstruction techniques, and that is where a different approach to ACL tears might be worth looking into.
A word of caution before reading the rest. Recent data has given us reason to temper our enthusiasm for direct repairs of ACL tears. Read the final paragraph and you can view the research on your own. Some recent studies suggest that up to 50% of ACL repairs fail. We are awaiting the results of the BEAR trial which should give us further clues as to whether or not a direct ACL repair is worth considering.
Why Should We Repair The ACL?
We have come a long way in terms of treating the ACL injured athlete. For many, we can restore your ability to return to the playing field and remain active. Unfortunately, a successful return to sports carries with it a nearly 25% chance of tearing your other ACL or the one you had surgery to reconstruct.
Your normal ACL has special nerves in it. These nerves provide proprioceptive feedback. That means that the nerves in the ACL help you know the position of your knee in space without looking at your knee… your brain can sense where it is based on the proprioceptive nerve fibers. Anyway, it turns out that proprioception is becoming a strong predictor of joint stability. If we improve your proprioception following ankle sprains and other injuries your perception of joint stability improves. This is also felt to be the reason why compression knee sleeves work to improve your sense of knee stability.
When the ACL tears those special nerves are torn too. Following a routine ACL reconstruction, the nerves do not regenerate. Therefore your new ACL does not contribute any proprioceptive feedback to your brain. This might explain why many knees still feel unstable, and it may explain, in part, the risk of developing osteoarthritis.
There are three significant reasons why an ACL repair might be preferred over an ACL reconstruction.
- We do not need to harvest a graft or tissue to use as your new ACL ligament. Right now we take one of your hamstring tendons or a portion of your patella tendon. That adds significantly to your pain. And it may contribute to problems after surgery as well.
- A successful ACL repair has been shown to enable those proprioceptive nerves to heal as well. This might improve your sense of joint stability and thus might improve the ability to return to sports and could theoretically diminish the risks of arthritic degeneration.
- Nearly 25 % of you who tear your ACL have a risk of re-tearing the ACL again. A revision ACL reconstruction can be a technically challenging procedure with inferior results when compared to your initial reconstruction. If we repair your ACL, then if you go on to re-tear your ACL it will be very straightforward to perform a reconstruction since we do not have to drill bone tunnels or alter your anatomy in any way to repair the ACL.
Can All ACL Tears Be Repaired?
No.. All ACL tears cannot be repaired. The ACL is attached to your thigh bone or femur and to your shin bone or tibia. Our current repair techniques only allow us to consider tears which occur high in the ACL near the femur insertion as a possible repair candidate. Also, the tear cannot be too old. If the tear is old, then the ligament will degenerate, and it may not be able to be brought back to the part of the bone it needs to be repaired to. Lastly.. some ACL tears look like the ligament exploded. That leaves us with very little viable ACL tissue to repair. In those instances, we may be able to perform a biological ACL Repair-Augmentation which I will describe in a moment.
What Are the Benefits of an ACL Repair?
In general, repairing torn tendons or ligaments is preferred over reconstructing them. When we reconstruct a ligament, we use a tendon from somewhere else in your body, remove the remnants of the torn tendon and put the new tendon in place to “reconstruct” your new ligament. It is an imperfect solution for a difficult problem. In addition to the benefits, I discussed before, if a tissue is repairable and has been shown to heal well and enable a return to an active lifestyle then it would be preferable to having a reconstruction.
How Is An ACL Repair Performed?
If you injure your ACL and choose to proceed with ACL surgery to improve your chances of returning to an active lifestyle, then we have a few options to explore. The potential benefits of an ACL repair are fairly clear. I will cover the potential downsides in a moment. If you choose to consider an ACL repair, then you understand that if your ligament is repairable, we will suture it back into place on the femur. As we discussed, you may be a candidate for a repair since all ACL tears are not repairable. If you are not a good repair candidate, then we will perform a routine ACL reconstruction or a biological augmentation.
What is a Biological ACL Repair Augmentation?
Certain ACL tears cannot be repaired. If the ligament cannot be repaired, but a good portion of the ligament remains attached to the tibia, then we can augment your torn ACL with a graft. In this case, we proceed in a manner very similar to an ACL reconstruction, but we do not remove your torn ACL. Instead, when we put the graft into your knee, we will place it right through the center of your torn ACL. That will allow your torn ACL to heal to the new graft. This reestablishes the normal “footprint” of your ACL, improves the blood flow to the graft, and it might allow those special nerve fibers to heal.
What Are The Risks of an ACL Repair?
The risks of any surgery apply to an ACL repair. That includes the risk of infection, stiffness, ligament failure, pain, blood clots, and the fact that the ACL might tear again if you sustain another twisting or collision injury.
So, our treatment of ACL tears continues to change and evolve. The more we understand the biology of the injury and the natural history of ACL injuries the better we will become at returning you to an active lifestyle with minimal risk of developing long term issues such as osteoarthritis. Perhaps paying more attention to repairing ACL tears instead of reconstructing them will be a positive step along the evolutionary path of our treatment of ACL injuries. Time will tell.
What are the results of a direct ACL repair?
There was a recent paper (2019) released regarding the results of an ACL repair versus a traditional ACL reconstruction. The authors of this paper found that nearly 50% of the repaired ACLs failed within the first two years. This is a significant problem. We will need to await the results of other studies before we determine if a direct ACL repair is a viable alternative for managing ACL injuries in an athletic population.