Knee Injury in Skiers
Unfortunately, one of the most common injuries that occurs during skiing is a tear of the anterior cruciate ligament. The anterior cruciate ligament, or ACL, is an important ligament to prevent one’s knee from having problems with twisting, turning, or pivoting activities. One can tear their ACL during skiing by a fall, a twist of the knee when one’s foot goes to the outside of the ski path, or when one falls back on their skis while skiing. While in most activities, an anterior cruciate ligament tear happens with a noncontact mechanism, it really has not been defined in skiing as well as to whether it is more common to tear one’s ACL and then fall, or to fall and then tear one’s ACL.
How to Identify an ACL Tear
One of the most common things that happens with an ACL tear is to feel a “pop”. This pop is a bone bruise that occurs when one’s joint slips forward (subluxes) and the ends of the bone on the outside of the knee contact violently and cause a bone bruise. Bone bruises happen about 75% of the time with ACL tears and luckily do not have consequences in most circumstances.
One of the most common things that happens after one tears their ACL is to have a lot of bleeding. The ACL has a good blood supply and when it is torn it commonly fills the knee with blood. Other concurrent injuries that can also fill the knee with blood after an injury while skiing include a kneecap dislocation, a meniscus tear, or tibial plateau fracture.
How to Treat a Torn ACL
The initial treatment of an ACL tear starts with a good program of self-directed or supervised physical therapy. One should work on regaining knee motion, try to decrease the swelling so your quadriceps muscles do not shut down, and to make sure that the knee gets back out straight. An early diagnosis is important for an ACL tear because when one has other injuries with an ACL tear, such as a meniscus tear, it can greatly affect one’s long-term prognosis for their knee function. It is especially important to try and diagnose meniscus tears which can be repaired with an ACL tear. This is because the meniscus is an essential cushion to the knee and when one loses their meniscus tissue, there is a very high risk of developing arthritis within the first decade after an ACL tear. Therefore, an examination by an emergency room physician or a sports medicine physician would be indicated when one is concerned that they may have torn their ACL, or if their knee swells up, after a skiing injury.
If one participates in twisting and turning activities, or is a young athlete, then one should consider undergoing an ACL reconstruction after they tear their ACL. We have recently published that patients in their 50’s and 60’s do equally well after ACL surgery as those in their 20’s.
How to Perform ACL Reconstruction Surgery
There are many factors which go into a successful ACL reconstruction. It is important to make sure that the treating doctor is up to date on the latest literature for treating ACL tears because ACL reconstruction techniques have undergone changes over the last decade which have improved one’s outcomes.
First, it is important to ensure that the ACL reconstruction graft is placed in the correct position. While this may sound elementary, the most common cause of failed ACL reconstructions is technical errors in the ACL graft placement. The most common error is to place the ACL reconstruction tunnel in the femur in the wrong position. This commonly occurs when one uses an older technique of drilling the femoral tunnel through an already drilled tibial tunnel, called the transtibial femoral tunnel reconstruction technique. The other most common technical error is to place the tunnel on the shin bone (the tibia) too far back from its normal attachment site on the tibia. This causes the graft to be straight up and down, or vertical, and does not control the rotation after surgery that a normal ACL would do. Recent studies by our group on both basic anatomy as well as electron microscopy have demonstrated that the ACL is basically adjacent to the anterior horn of the lateral meniscus and best functions when it is placed back in its normal position.
ACL Graft Choice
The second most common important choice for an ACL reconstruction is the graft material used. Probably the most important decision to make if one is less than 55 years of age is to use one’s own tissues for an ACL graft rather using it from a cadaver (allograft). It has been well-documented that the use of cadaver material for ACL grafts in young patients has a very high failure rate and should not be used. If one is a bit older and wishes to use cadaver material, it is important to recognize that the graft will not grow into one’s body at the same rate as using one’s own graft material and it may take up to 50% longer. Thus, one should avoid going back to full activities for at least 9-12 months after an ACL reconstruction with a cadaver graft to ensure that the graft does not tear because it is not fully healed in place.
The gold standard ACL reconstruction graft is the patellar tendon graft. This graft is taken with a piece of bone off one’s kneecap and the shin bone and is the most common graft used for professional and high-level athletes. Another common graft is the hamstrings graft. These grafts are used in many centers, but do have a slightly higher risk of infection, graft failure, and end up a bit looser than the patellar tendon graft. Another much less frequently used graft is the quadriceps tendon graft. However, recent studies have shown that this graft causes the most residual quadriceps weakness of all autografts, and probably be used with caution until further studies are performed on it. In any event, choosing between a patellar tendon or hamstrings graft should be made with one’s surgeon and is recommended that one choose what your surgeon feels most comfortable with performing in your particular case.
Treating Associated Knee Injuries
The other important thing with an ACL reconstruction is to be sure to address all associated injuries with an ACL tear to minimize the risk of both developing arthritis down the road, as well as having a lesser chance of having an ACL reconstruction graft fail. The most common associated injury which needs to be addressed with an ACL tear is a meniscus tear. The meniscus is the cushioning cartilage that is important for joint health. In effect, it is probably more important to repair the meniscus and have it heal successfully than the ACL reconstruction itself. Therefore, one should strive to have a meniscus tear repaired at all cost when one has an ACL tear. In our most recent series of over 300 patients, we performed meniscus repairs in 55% of ACL reconstructions. The other associated injury to look for with an ACL tear is injuries to the collaterals. A medial collateral ligament, or MCL, tear is a common injury that happens with an ACL tear. When these are not complete tears, they almost always heal. However, when the knee is unstable when it is out straight, or if the MCL tears off the tibia, they often do not heal and may need to be reconstructed with your ACL reconstruction. A combined tear of the LCL, or lateral (fibular) collateral ligament, also can occur. This is a very common injury while skiing. Unfortunately, complete tears of the LCL rarely heal and one should have a concurrent ACL and LCL reconstruction when they happen in combination in all circumstances. We have published on a large series of patients with surgical outcomes with LCL reconstructions with the technique developed in my research lab and have found them to be extremely successful.
The other essential component of an ACL reconstruction is the postoperative rehabilitation. Even if one has a “perfect” ACL reconstruction with one’s own tissue placed in the ideal position, one has to intertwine this reconstruction with a postoperative rehabilitation program. The initial principles are to make sure that one’s knee gets out straight, that swelling is reduced, and that one works on your kneecap motion. It is important to get the knee out straight, because if one does not, the hamstrings muscles can go into spasm and prevent the knee from going out straight which may require a later surgery to address this. It is important to decrease the swelling because swelling both causes increased pain and also shuts down the quadriceps muscles. It is also important to work on kneecap motion because the kneecap can become scarred after an ACL reconstruction, both due to scarring from the original injury and scarring due to the surgery itself, and this can result in kneecap arthritis. Therefore, getting into therapy on postoperative day one is part of an essential ACL reconstruction rehabilitation program that we espouse.
Knee Arthritis After ACL Reconstruction
We have published a metaanalysis recently which reported that over 50% of people develop osteoarthritis within 20 years of tearing their ACL. The most important underlying factors are to ensure that one has a meniscus repair, rather than having the meniscus taken out, with an ACL reconstruction. It is obvious that one can see a theme here, with repairing one’s tissues and addressing all associated injuries being very important to ensuring that one has a well-functioning knee that you can participate in sports for a long time.
In summary, an ACL tear can be a very devastating injury because one will be out of sporting activities for 9-12 months. However, being an advocate for one’s own self and choosing the correct treatment can ensure that one will be able to continue to participate in sports long into the future after an ACL reconstruction.
NOTICE: Effective June 1, 2019, Dr. LaPrade will be practicing at Twin Cities Orthopedics in both the Edina and Eagan Minnesota Clinics and Surgery Centers