By Dr. Jeff Daniels EBS Medical Columnist

One of the more devastating injuries we see coming off the ski hill is a fracture involving the knee joint, also known as a tibial plateau fracture. It’s much more likely to be seen in skiers than in snowboarders, and almost always requires surgery.

The knee joint is made up of three bones: the femur (thigh bone), tibia (shin or lower leg bone), and patella (knee cap). The joint itself basically consists of the widened and flattened ends of the femur and tibia held together by ligaments, tendons, and other soft tissues.

The joint is lined with cartilage covering the end of the femur as a solid coating, and formed into two disks – the medial and lateral menisci – on the upper surface of the tibia. This tibial joint surface and the upper tibial bone substance are what get damaged in this injury.

Every ski season, we average more than one tibial plateau fracture per week. This season, we didn’t see this injury through the first seven weeks, but then we had three in the last week of January. It’s hard to explain, except that the overall number of all knee injuries increased at the same time. I’m guessing it was a result of warmer weather making for thicker snow, which is more likely to catch a skier off guard than dry powder.

The mechanism of injury that produces this fracture varies, including a twisting fall, a tumble or cartwheel that causes the knee to buckle severely, and rapid deceleration when hitting a tree. The type of twist that produces an ACL tear – which is a much more common injury – can also produce a tibial plateau fracture, and the ACL itself is often torn when the plateau is fractured.

When the tibial plateau is broken, the knee swells immediately, because of bleeding into the joint. Most people will be instantly disabled and in a great deal of pain, while a rare few are able to get up and ski down the mountain.

Of the three tibial plateau fractures that we’ve seen this winter, only one was severe. It occurred in an expert skier from South Dakota, at the end of the day when the light was flat, causing him to misjudge a turn. As he fell, his friend skiing with him heard a crack, and ski patrol had to sled him down. His X-ray looked like a chain saw cut vertically through his knee.

The next two unlucky skiers had milder damage to the knee joint, where it took an experienced eye to not only suspect the fracture on examination, but to even see it on X-ray. One of these patients, thinking he wasn’t badly injured, wanted to limp out of the office, and I had to talk him into getting the knee X-rayed. It’s lucky that I did, because the last thing you want to do is bear weight on a knee with a tibial plateau fracture.

Surgery is needed to repair the knee in this type of injury, but it’s not considered an emergency like a severe boot-top fracture of the tibia and fibula. Most patients can wait a couple of days, as long as the knee is immobilized and crutches are used to keep weight off the leg. A CT scan is necessary to map out all the details of the damaged bone.

The worst thing about a tibial plateau fracture is that even in the best of hands, it is not likely the knee joint will return to 100 percent normal. I’m glad this is not a common injury.

Dr. Jeff Daniels has been practicing medicine in Big Sky since 1994, when he and his family moved here from New York City. A unique program he implements has attracted more than 700 medical students and young doctors to train with the Medical Clinic of Big Sky.