Knee and lower leg injuries are among the most common injuries seen in alpine skiing. The nature of these injuries has changed over time as equipment has evolved. In the past, tibia (leg) fractures were much more common. With the introduction of modern binding systems, we have seen the incidence of tibia fractures decrease, but we have also seen a rise in certain knee ligament injuries, specifically the ACL.
A ligament is a structure than connects a bone to another bone. There are four main ligaments that stabilize the knee joint. There are two in the middle that cross, called the cruciate ligaments (ACL and Posterior Cruciate Ligament [PCL]). There is one on the inside (medial collateral ligament [MCL]) and one on the outside (lateral collateral ligament [LCL]). The ACL is inside the knee joint and its function is to keep the shin bone (tibia) from coming too far forward with respect to the thigh bone (femur). It also is very important for rotational stability.
ACL injuries occur in all types of alpine skiers from beginners to world championship skiers like Lindsey Vonn. ACL injuries often occur as a result of a twisting mechanism. Dr. Slauterbeck, orthopedic surgeon at the UVM Medical Center, describes the mechanisms of injury specific to skiing in his blog. Frequently, at the time of injury there is a report of hearing or feeling a “pop.” Some people have considerable pain right away, while others have very little pain. Some skiers are even able to continue skiing, but usually their knee doesn’t feel quite right. Often, there is swelling which develops after the injury but it may not be noticeable for several hours or even until the next day. In some cases, the injury may go unrecognized for a period of time because of the lack of pain and swelling.
Over time, any pain and swelling associated with the initial injury usually will go away. The main ongoing problem associated with an ACL tear is instability. Patients complain that their knee feels “loose” or “gives out” and they don’t trust it. This usually occurs with pivoting and jumping activities, but sometimes even with just walking or going up and down stairs.
The diagnosis of an ACL tear is made by combining the patient’s history with the physical examination. An MRI can also be helpful for confirming the injury and evaluating other structures in the knee. It is not uncommon for other structures to be injured along with the ACL. Common associated injuries include MCL tears and/or meniscus tears.
Treatment of an ACL injury is an individual decision based on the patient’s symptoms and activity level. Many people can walk, bike, swim and even run without an ACL, but activities that involve cutting, pivoting, twisting, or quickly changing direction are problematic because of lack of stability. If you do tear your ACL and your knee is unstable, there is risk of additional injury to the knee, especially to the meniscus. Meniscus tears have clearly been shown to be related to the development of osteoarthritis.
Unfortunately, the ACL does not heal on its own like some ligaments. In the past, we tried doing direct repairs, essentially sewing the ends of the ligament together. This was associated with very high failure rates. Currently, the surgical treatment of ACL tears involves a reconstruction, or replacement, of the ACL with a graft. In general, the results of ACL reconstruction are very good with many patients able to return to a very high activity level.
A major area of interest is preventing ACL injuries in the first place. Dr. Robert Johnson, professor emeritus at the University of Vermont, and his colleagues have studied skiing and snowboarding injuries for more than 40 years at the Sugarbush clinic. This is one of the largest databases of skiing injuries worldwide. A large focus of their efforts has been on injury prevention and skiing safety. As discussed in Dr. Slauterbeck’s blog, they have identified several specific mechanisms of ACL injury in skiers. They have also described effective methods of prevention. Key areas of prevention involve making sure your bindings are appropriately set and functioning properly, and learning how to avoid positions that put the ACL at risk. Skiing in control is obviously a factor, as well.
For more information about skiing injuries, skiing safety, injury prevention and ACL tears, visit the Vermont Ski Safety website (vermontskisafety.com) and the American Orthopaedic Society for Sports Medicine (AOSSM) website (sportsmed.org).
Nathan Endres, MD, is an orthopaedic surgeon at FAHC and assistant professor at UVM. He is fellowship trained in sports medicine, shoulder surgery and orthopaedic trauma. He is a former ski racer and member of the United States Ski and Snowboard Assocation (USSA) physician pool.