Surgeons at a children’s hospital in New Zealand present the results of 11 years of treatment for large osteochondral fractures of the lateral femoral condyle. The area affected is the cartilage covering the end of the femur thighbone in the knee.
Instead of removing the torn fragments (standard practice), the surgeons held the detached pieces together with a special implant until healing occurred. They used polyglycolic acid rods for the fixation. The rods or pins are small bioabsorbable implants. During the healing process, the polyglycolic acid is absorbed and replaced by living tissue.
Eight patients were followed from injury through follow-up for at least five years. The initial injury was a twisting knee motion with the foot planted on the ground. The trauma occurred in children between the ages of 12 and 15. All of the patients had generalized ligamentous laxity throughout the body, which may have contributed to the injury.
Although the anterior cruciate ligament (ACL) inside the knee was not torn, several patients had a knee dislocation at the time of the osteochondral fracture. The shearing load of the twisting force may be what caused the patella to dislocate, rather than occurring as a direct result of the osteochondral fracture.
Many times these kinds of injuries are much deeper and broader than appreciated. X-rays and MRIs don’t always show the full extent of the injury. It isn’t until the surgeon performs the operation that the severity is clearly seen.
Taking the piece(s) or fragments out leaves a large hole that fills in with fibrocartilage. Since it’s on a weight-bearing surface, over time, the bone deteriorates and the joint develops early degenerative arthritis. This new procedure has the potential to keep this from happening.
MRIs were used to observe the healing tissue. Normal function of the joint articular cartilage returned and remained present during the follow-up. There were no poor results. Most of the children had normal X-rays, normal function for their age, and only a small amount of cartilage thinning. Everyone was followed for at least five years. The average length of time the patients were followed was more like nine years.
The authors weren’t sure the exact mechanism of healing using this method of repair. It seems that restoring the layer between the cartilage and bone resulted in a normal transition from layer to layer. It’s possible the joint recruits bone marrow cells to produce healthy transition cells between layers.
Normal function of the articular (joint surface) cartilage was the long-term goal. So far, this goal has been met in the short-term and medium-length periods of time. The research will continue to follow this group of patients and perfect the technique with new patients.