Our 15-year-old son is an avid snowboarder. When he isn’t out snowboarding, he’s in the back yard practicing on his home made jumps. Unfortunately, he was just diagnosed with OCD of the knee. No more snow boarding or practice for a while. How long does it take to get over this problem?

Osteochondritis dissecans (OCD) is a problem that affects the knee, mostly at the end of the big bone of the thigh (the femur). A joint surface damaged by OCD doesn’t heal naturally. OCD mostly affects the femoral condyles of the knee. The femoral condyle is the rounded end of the lower thighbone, or femur.

Each knee has two femoral condyles, referred to as the medial femoral condyle (on the inside of the knee) and the lateral femoral condyle (on the outside). Like most joint surfaces, the femoral condyles are covered in articular cartilage. Articular cartilage is a smooth, rubbery covering that allows the bones of a joint to slide smoothly against one another.

The problem occurs where the cartilage of the knee attaches to the bone underneath. The area of bone just under the cartilage surface is injured, leading to damage to the blood vessels of the bone. Without blood flow, the area of damaged bone actually dies. This area of dead bone can be seen on an X-ray and is sometimes referred to as the osteochondritis lesion.

The lesions usually occur in the part of the joint that holds most of the body’s weight. This means that the problem area is under constant stress and doesn’t get time to heal. It also means that the lesions cause pain and problems when walking and putting weight on the knee. It is more common for the lesions to occur on the medial femoral condyle, because the inside of the knee bears more weight.

With a mild lesion, patients are treated conservatively (nonoperative approach). It sounds like that’s the course your son is on. Keeping weight off the damaged area helps keep blood flowing to the area and prevents further wear and tear of an already torn area. But repair and recovery can take weeks to months. Many athletes aren’t patient enough to wait it out but they must do so for a good result.

The surgeon will follow your son at regular intervals. X-rays will show the progress of healing and give you a better timeline to expect. Avoidance of sports activity and strict immobilization with non weight-bearing is absolutely essential for a good result.