Surgeons Choose Repair Over Removal for Osteochondritis Dissecans

Patients and surgeons faced with how to treat a grade IV osteochondritis dissecans (OCD) defect have two choices: remove it or screw it back in place. In this article, the long-term results of a small number of patients (12) are reported following surgical fixation with a screw.

Osteochondritis dissecans (OCD) is a bone defect in a joint (usually the knee). 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 good 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.

In the case of these 12 patients, the knee was affected. A fragment of cartilage or cartilage with a piece of bone attached to it came loose and became a free-floating body inside the joint. The cause of OCD varies from patient to patient. The most common causes are repetitive microtrauma (most common in athletes), inflammation, loss of blood supply, and bone abnormalities.

The degree of severity depends on how large the fragment is and whether or not it has detached causing a hole in the bone where it came from. A mild (grade I) case of OCD means there's a lesion but the frayed piece of cartilage is stable. In other words, it is still attached to the bone. During arthroscopic exam, the surgeon cannot move the fragment away from the bone. With a stage II lesion, the cartilage is starting to show some signs of separation between the cartilage and the bone.

Stage III lesions are partially detached. An MRI can be used to see just how attached (or detached) the fragment is. And with a stage IV lesion (the subject of this study), the fragment has come loose, leaving a crater or hole in the bone. This hole is referred to as a grade IV defect. The loose fragment of cartilage usually has a piece of the underlying bone still attached.

So the dilemma becomes: should the surgeon put the piece back in place and screw it in? Or would it be better to remove the loose fragment? After removal, the surgeon smoothes over the bone or fills the hole in with a bone graft or a cartilage implant. To help answer this question, the authors present the results of the fixation method they used in this small case series.

The surgeons searched their patient records to find all patients who were treated for OCD lesions requiring surgery. They were able to find 12 patients who had a grade IV defect that was repaired with screw fixation. Remember, this means the loose fragment was a layer of joint cartilage with bone attached from underneath.

The surgical procedure required the use of one to four metal screws. The screws were sunk down far enough into the cartilage and bone so that the head of the screw was flat or flush with the surface. The surgeon made sure there was a perfect fit between the loose fragment and the hole. If the fragment was too large, it was shaved and shaped to fit exactly. If the fragment was too small, they used extra pieces of bone packed in around the fragment to fill in the space.

The patients were instructed to move the knee but keep all weight off of it for 12 weeks. The nonweight bearing status helps the area heal without further disruption. At then end of three months' time, the screws were removed. Screw removal required a second (arthroscopic) surgery. Arthroscopy allowed the surgeons to re-examine the area and see how it looked.

Early results were very good. Only one patient had a nonhealing response. That person had a second surgery early on (at 12 weeks) to repeat the fixation procedure. Everyone else had a stable repair. The surgeon used a probe to try and move the fragment and reported it was no longer loose.

The patients were followed for three to 15 years. Their symptoms, level of daily activities, and sports or recreational participation were recorded during that time. They were also asked questions about their quality of life (related to the knee) and overall knee function.

What did they find years later? There were no symptoms of osteoarthritis (knee pain with activity) and everyone reported normal function with daily activities.

The authors concluded that surgical replacement and fixation of grade IV osteochondritis dissecans works well and should be used whenever possible. Certainly, this method of repair is preferred to the other choice of removing the fragment. There's a better chance that the patient will get close to normal anatomy and function with repair. Patients won't get perfect results, as they may be limited in their ability to participate in sports activities without pain or stiffness.

Reference: 

Robert A. Magnussen, MD, et al. Does Operative Fixation of an Osteochondritis Dissecans Loose Body Result in Healing and Long-Term Maintenance of Knee Function? In American Journal of Sports Medicine. April 2009. Vol. 37. No. 4. Pp. 754-759.

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