Dr. George Meets the ACL Rupture

13#7 Dr. George

ACL Rupture

“My accident happened two weeks after the Olympics during boardercross training at Kirkwood, California. At first, I didn't want to compete because my arm was still in a cast after a wrist fracture. In the end, I did it for fun.

“After a stupid crash, I became so angry with myself I bolted down the rest of the course without being familiar with it–very clever! As I cleared a straight jump I found myself in front of an uphill landing–instead of a nicely prepared landing. You can imagine the rest.

“The landing was not exactly soft. My front leg twisted inward and I got a funny feeling in my knee. I was still able to ride and there wasn't any major swelling or pain, but I decided to have my leg checked anyway. To my surprise, the doctor said I ruptured the anterior cruciate ligament.

“Ligament rupture or not, I went to Maui for the holidays and when I was able to surf five days later, I was convinced that the diagnosis had been wrong. But two weeks later, back on my board at the U.S. Open, my front knee felt unstable. I didn't want to take a risk, so I had an MRI at home. Unfortunately, the MRI confirmed the diagnosis of the American physician, rupture of the anterior ligament of my left knee–end of the season.”–Anita Schwaller

Serious knee injuries, like a rupture of the anterior crusciate ligament (ACL), are less frequent in snowboarding than in skiing. One reason for the low injury rate is the permanent fixation of the feet on the board. In addition, the use of soft boots allows for a more even distribution of force to the ankle and knee, though the risk of ankle injury is higher. Generally, the front leg is more often affected.

Where in the knee is the anterior cruciate ligament (ACL) and what is its purpose?

The joints of the knee are dynamically stabilized not only by the surrounding muscles, but also by various strong ligaments. The main stabilizers are the collateral ligaments on the inside and outside of your knee, which keep the knee stable for internal and external movements, and the anterior and posterior cruciate ligaments, which are positioned in the center of your knee joint. The ACL stabilizes the knee toward the front and keeps it from slipping out in a forward direction. If the thigh muscles are too weak, in the event of an ACL rupture, the knee becomes unstable and you lose control of your knee joint. This can seriously damage cartilage.

How do ACL ruptures happen in snowboarding?

The ACL is so strong you could tow a small truck with it. But it's very fragile when exposed to shear forces. This is what occurs during a backward fall with the body in rotation: the stiff hard boot, or the stiff highback in soft-boot bindings, pushes your leg forward while the body falls backward, distributing a high shear force to the ACL. When one foot detaches from the binding, the knee joint is subjected to strong torsion forces because of the long lever of the board, which can easily lead to an ACL rupture.

How can this injury be avoided?

You can reduce the risk by wearing soft boots with good ankle support. Never wear ski boots, and always make sure your bindings are closed properly.

What are the symptoms of an ACL rupture?

Many of these injuries may remain undetected for a while because an ACL rupture is not necessarily very painful. Another typical sign, swelling of the knee, can appear many hours later. Very often, as in Anita's case, you don't become aware of the injury until the joint feels very unstable.

What can be done in such a case?

Generally, an ACL rupture doesn't heal by itself. But, not every injured ligament has to be replaced by surgery. If you really feel an instability, you can try to compensate the loss of the ACL with good, specific muscle training. A knee brace might provide additional support. If the knee joint remains unstable, you often have no other choice but to pass under the surgeon's knife to replace the ligament. It takes almost a year to get back to snowboarding, so try to stay away from it.

Dr. George Ahlbäumer is known as one of Europe's top orthopedic surgeons specializing in snowboard injuries, based at the Clinic Gut in the Center of Bone and Joint Surgery in the Swiss Alps of St. Moritz.