HERSHEY, PA. — Otherwise healthy adolescents who had internal fixation surgery for osteochondritis dissecans of the knee returned to their sports activities about 8 months later, Dr. Mininder S. Kocher reported at the annual meeting of the American Orthopaedic Society for Sports Medicine.
The data argue in favor of internal fixation, especially for children approaching skeletal maturity who have less time to heal nonoperatively.
The overall healing rate was 85%, based on at least 2 years of follow-up data from 26 knees in 24 patients whose average age was 14 years, said Dr. Kocher, an orthopedic surgeon at Children's Hospital Boston. The cases included 9 stage II lesions (fissured), 11 stage III lesions (partly attached), and 6 stage IV lesions (detached). Other studies have shown similar healing rates of 80% or higher.
Osteochondritis dissecans (OCD) is a relatively rare disease (about 15–30 cases per 100,000 persons in the year 2000) in which a loose piece of bone and cartilage separates partly or completely from the joint. Symptoms include pain, stiffness, locking of the joint, and a sensation that the joint is giving way.
The cause of OCD remains unclear, although possible causes include repetitive microtrauma, poor bone growth, and genetic predisposition. Most cases occur in active boys aged 10–20 years, but the diagnoses in girls have increased as more girls play competitive sports. Dr. Kocher's study included 13 boys and 11 girls.
Healing was evident 6 months after surgery based on several scores, including the International Knee Documentation Committee, Lysholm, and Tegner scales, which measure knee function in athletic patients.
The average Tegner activity level score, which uses a scale of 1–10, increased from 4.9 before surgery to 7.4 after surgery.
The healing rate was slightly lower in the seven patients who had undergone previous surgery for OCD than in those with no prior OCD surgery (71% vs. 89%).
After surgery, the patients recovered by performing careful weight-bearing and range-of-motion exercises, and gradually returning to sports.
There were no significant differences in healing rate based on the type of lesion and, in fact, all six of the cases of stage IV (unstable lesions) healed. A lateral vs. medial location had no apparent effect on healing, and no significant complications were reported in any of the patients.
There were four cases of unhealed lesions after the procedure (15%).
Two of the cases were treated with chondral resurfacing, and the other two were treated with a second internal fixation; all four patients were able to resume their sports activities.
The study was limited by its small size—which prevented subgroup comparisons—and by its retrospective nature.
“When faced with an unstable juvenile OCD lesion of the knee, we are often forced to choose between internal fixation or fragment removal with a chondral resurfacing technique,” Dr. Kocher said. “Given the relatively high healing rate, good functional outcome, and low complication rate, we would advocate internal fixation of these lesions when technically possible.”