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As the Super Bowl approaches, one of the major stories is the return of Rob Gronkowski. Gronkowski, the tight end for the Patriots, sustained a major knee injury last year in a game against the Cleveland Browns when tore both his anterior cruciate ligament (ACL) and his medial collateral ligament (MCL). Many worried that if he would ever be able to return to his elite level of play. However after undergoing an ACL reconstruction, he not only returned this season, but also returned to his All-Pro form. As did Tom Brady, who also sustained an ACL tear in 2008. Concussions have rightfully been prominent in the discussion of NFL injuries recently, however a poll by USA Today last year found that knee injuries were even more feared by NFL players than head injuries1. While players worried about concussions and their long-term consequences, most players feared a devastating knee injury that might be a career-ending event. And until a few decades ago, it often was.
What exactly is the ACL?
The ACL is one of the 4 major knee ligaments and it helps keep the knee stable with twisting and cutting maneuvers. It runs from the femur to the tibia and is located in the center of the knee. Unfortunately with an unexpected cut, twist, or an awkward landing, the ACL can tear. Typically people hear a “pop” and know something serious has happened to their knee. Surprisingly, most people are able to walk off under their own power, but soon thereafter the knee starts to swell and get stiff. Unlike other ligaments in the knee, the ACL will not heal on its own. The ACL is typically not needed for straight-ahead activities such as walking or even light jogging. So if people have no intention of returning to cutting or twisting activities, non-operative treatment may be appropriate. However, if individuals desire to remain active and return to sports, an ACL reconstruction is often recommended.
Who tears their ACL?
While anyone can sustain an ACL injury, most tears occur as a non-contact injury in young, active individuals, especially those participating in competitive sports such as soccer, basketball or football. However, participating in any sport that requires cutting, twisting, or landing, puts you at risk for an ACL tear, regardless of age. Numerous studies have shown that women are 3 times more likely to sustain an ACL tear than men, though the reasons behind this is not well established2. It may be structural differences in the ACL, or possibly as the result of neuromuscular or hormonal differences between genders.
What do I do if I tear my ACL?
Most people are able to walk and function reasonably well without an ACL, however returning to high level cutting or twisting sports can be challenging. Without an ACL there is a concern about what happens to the cartilage in the knee if it remains unstable. If you tear your ACL, you should discuss with your surgeon whether you need an ACL reconstruction, and if so how it should be done. Of most importance is not to rush into surgery. Studies have shown it is important to allow the knee to calm down and the range of motion to return to normal before having surgery; otherwise post-operative stiffness can be a significant problem3.
How is it reconstructed?
Over the past several decades there has been an evolution in how ACL tears are treated. It wasn’t until the 1960’s and 70’s that orthopaedists realized that an ACL tear was actually a significant injury. Once it was realized that tearing the ACL led to instability and eventually arthritis, ACL injuries have become the most researched topic in orthopaedics. Early ACL surgeries were done as an open procedure where a graft was placed in a tunnel drilled into the femur and tibia. With the rise of arthroscopic surgery in the 1980’s, techniques became popular that allowed the surgery to be done through smaller incisions. This led to a boom in ACL reconstructions and now 50,000 reconstructions are performed per year4. Unfortunately, doing so many ACL reconstructions has led to some bumps in the road. Researchers found that people were still getting arthritis and having instability, despite undergoing a reconstruction. It was realized that with the current reconstruction techniques, surgeons were not consistently placing the ligament in its native location. Over the past decade, there has been a major emphasis on surgical techniques that restore the normal anatomy, and produce a more modern “anatomic ACL reconstruction”.
Another important aspect of ACL surgery is what graft is used to reconstruct the ligament. A variety of grafts can be used, and each has their pro’s and con’s. The two major categories of graft choices categories are allografts (cadaveric donor grafts) or autografts (your own tissue). While studies have shown that all grafts typically have good outcomes, more and more studies are showing allografts are associated with higher failure rates, especially in younger, highly active individuals. When Carson Palmer of the Arizona Cardinals retore his previously reconstructed ACL, many speculated that it was because cadaveric tissue was used in his initial surgery5. But if you aren’t trying to return to professional or collegiate sports, the use of allograft tissue may be worth a discussion with your surgeon. Historically there have been two major autograft choices. A patellar tendon graft is where a small piece of bone from your patella and tibia are taken along with a strip of tendon and this is to reconstruct the ACL. The other option has been to use the hamstring tendons to reconstruct the ligament. Both have been very successful for ACL reconstructions. A new graft has recently emerged, the quadriceps tendon, and early data suggests may also be as good of graft choice as the other options.
How long will it take me to get back?
In the late 1980’s and early 1990’s surgeons began to realize that it was important to not only restore stability to the knee, but it was important for people to get normal strength and motion back if they wanted to return to sports or activities. Surgeons began to allow patients to move their knee early after a reconstruction and while scary at first, surprisingly the grafts did not “stretch out”6. Patients actually got better faster and were returning to sports at a higher level than ever. Now it is well accepted that getting your motion back early after surgery is one of the most important factors to having a good outcome. Once motion comes back, strength usually follows. Typically most surgeons will tell patient that getting back to sports will require approximately 6 months after surgery, however depending on graft choice this can vary from 4 months to 1 year.
If I have surgery can I reinjure it?
Yes, it is possible to retear an ACL after it has been reconstructed. Much as with sustaining a first ACL tear, if you return to risky sports at high levels, you are at higher risk of sustaining a retear. In young active females the risk of sustaining a second ACL can be as high as 20%7. Interestingly enough, women seem be twice as likely to tear their other ACL as they are to retear their reconstructed knee. While this may be related to the size of the native ACL versus the larger, reconstructed ligament, this has not been completely proven as of yet.
While Rob Gronkowsky, Tom Brady and numerous other NFL athletes have made returning from ACL surgery look easy, it is actually a complicated process that requires teamwork to get back to such a high level of activity. It takes a motivated patient, precise surgical technique and a skilled therapist to get back to such high levels of activity. So if you, a friend or family member sustains an ACL tear, seek out an orthopaedic surgeon who is part of a sports medicine team to help get back in the action.
- Prodromos CC, Han Y, Rogowski J, Joyce B, Shi K. A Meta-analysis of the incidence of tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy. 2007;23(12):1320-5.
- Shelbourne KD, Wickens JH, Mollabashy A, DeCarlo M. Am J of Sports Med. 1991;19(4): 332-6
- Frank CB, Jackson DW. The science of reconstruction of the anterior cruciate ligament. J Bone Joint Surg Am. 1997;79:1556-1576
- Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. American Journal of Sports Medicine. 1990;18(3):292-9
- Shelbourne KD, Gray T, Haro M. Incidence of subsequent injury to either knee within 5 years after anterior cruciate ligament reconstruction with patellar tendon autograft. Am J Sports Med. 2009;37(2):246-51