During the last ten years Dr Stone and his colleagues, at The Stone Foundation for Sports Medicine and Arthritis Research, have been using a pioneering technique for Articular Cartilage Transplantation. This procedure is appropriate for patients who have focal areas of damage to the articular cartilage of the knee joints. Often, this damage represents the early stages of osteoarthritis of the knee. Articular cartilage paste grafting is designed to re-grow articular cartilage in the areas that have been damaged, thus delaying the progression of degenerative changes and an eventual joint replacement.
The technique involves harvesting the patients own cartilage and transplanting the tissue to the defective area. It is all performed through arthroscopic surgery and in only one surgical procedure. During arthroscopic surgery the findings of the MRI scan can be fully evaluated. The dead tissue is then removed before the area of cartilage damage is treated with a ‘micro-fracture’ technique, where small holes are made in the bone underneath the cartilage. This provides a bleeding surface that initiates a healing response. A graft of cartilage and bone is then ‘harvested’ from a non-weight bearing area of the knee joint. This graft is then ‘morselized’ into a paste in the operating room and, using the arthroscopic tools, it is impacted into the area of cartilage damage. The bleeding bone actually helps the graft to stick in place, but the graft remains fragile for several months after the procedure.
After the operation the patient must wear a hinged knee brace and is not allowed to weight bear for 4 weeks. During this time, a continuous passive motion (CPM) machine is used, which automatically bends and straightens the knee for 6 hours each day. After two weeks, non-weight bearing exercises, such as pool running and light resistance stationary cycling, are permitted under the supervision of a Physical Therapist. After three months, a gradual return to sporting activities is allowed, although impact exercises are not advised during the first 12 months.
Dr Stone, what level of activity can be expected following successful articular cartilage transplantation surgery and rehabilitation?
“Our goal is to return the patients to full sports fitter faster and stronger than they were before their injury. However, if the lesion is on the weight bearing surface or associated with extensive arthritis the results will last longer if the patients return to cycling and swimming rather than impact sports.”
What are the risks associated with this procedure and which patients would this technique not be appropriate for?
“Anytime we operate on a patient the risk is that the patient might be made worse by the procedure (more pain, stiffness, loss of motion, etc.). Patients who are unable to follow our rehabilitation program are not appropriate. Patients who have lost their meniscus cartilage, their ACL or have bowlegs need to have these problems corrected at the time of cartilage grafting (by meniscal transplantation, ACL reconstruction or osteotomy.)”.
What are your initial findings in patients who have already undergone articular cartilage transplantation?
“The patients have had a high rate of return to sports with improvement in pain scores, activity scores and function scores by at least 25% in more than 85% of patients, over the last 13 years (180 patients).”
How does this compare with the natural history of articular cartilage defects?
“Cartilage defects that are not symptomatic and found by chance at surgery for a torn ACL for example may heal on their own. Defects and arthritic areas that are painful generally do not heal. However, they can often be successfully treated by paste grafting.”