Cell Therapy Product Improves Knee Cartilage RepairIn this study, surgeons from the Netherlands (Belgium) present long-term results of a study previously published comparing two methods of treating knee articular cartilage damage. Articular cartilage refers to the fibrous structure directly over the bone protecting the joint and helping produce smooth gliding action. What makes the research of this Belgium group so unique is the use of a cell therapy product in one of the groups. Cell therapy is designed to prevent breakdown of the repair. Here's a little background on the subject.
Knee articular cartilage doesn't repair well by itself. There isn't a lot of blood supply to the area. So left untreated, patients with this problem often develop knee pain, early osteoarthritis, loss of function, and eventually disability. In the last 10 years, joint resurfacing techniques such as microfracture (MF) and autologous chondrocyte implantation (ACI) have been developed to address this problem. But there are problems with these procedures.
The authors of this study are addressing the problems associated with autologous chondrocyte implantation (ACI). In this procedure, normal, healthy articular cartilage cells are removed from the patient and taken to a lab. In the lab, scientists use the cells to grow more cells -- enough to fill the hole or defect in the patient's joint and repair the damage. But surgeons have discovered that over time, the lab grown chondrocytes (cartilage cells) seem to lose their ability to remain chondrocyte cells. They start to become unstable and lose their form and structure, a process called dedifferentiation. The end-result is joint breakdown again and early arthritis.
The solution to this problem may be a new method called cell therapy. With cell therapy, the autologous cells (harvested from the patient) are treated (processed) in a special way to preserve the cells' ability to remain stable and unchanged after implantation into the knee. This cell therapy procedure called a characterized chondrocyte implantation (CCI) is a slight variation of the autologous chondrocyte implantation (ACI).
In the first part of this study, patients with painful cartilage defects on the femoral (upper or thigh) side of the knee joint were divided into two groups. The first group had the microfracture procedure (tiny holes drilled into the joint surface to create bleeding and stimulate a healing response). The second group had the characterized chondrocyte implantation (cell therapy). Short-term results were reported after 12 months. The same two groups of patients were followed an additional 24 months for a total of 36 months (three years). This report provides the results after three years for those two groups.
The authors were watching for several things during follow-up. They wanted to see how patients compared symptom-wise (pain, swelling, knee function), but they also wanted to see if there was a difference in outcomes based on how long patients waited before getting treatment. They used serial (repeated) MRIs and a special test called the Knee Injury and Osteoarthritis Outcome Score (KOOS) to measure results. The KOOS gives information on overall knee function including pain, stiffness, activity level (daily activities and sports or recreational activities), and quality of life.
The MRIs showed that patients having a microfracture procedure showed improvement in the cartilage for up to 18 months. But the characterized chondrocyte implantation group had ongoing biologic growth and repair for much longer. Not only that, but there was evidence of bone overgrowth and degeneration of the repair tissue with microfracture that wasn't present in the cell therapy group. Likewise, KOOS scores of knee function were better for the cell therapy group, especially for pain and quality of life. There were fewer adverse effects of treatment and fewer treatment failures in the characterized chondrocyte implantation (CCI) group.
All in all, the long-term results of this first published study using cell therapy products to stabilize cartilage implantation seem to point to characterized chondrocyte implantation as a better treatment procedure than either autologous chondrocyte implantation or microfracture. The procedure is not without some potential problems. Overgrowth of cartilage and joint crepitus (crunching sound made by rough joint surfaces rubbing against each other) occur more often with implantation than with microfracture.
But as a technique to repair damaged articular cartilage in the knee and provide long-lasting, normal movement of the joint, autologous chondrocyte implantation treated with cell therapy to form characterized chondrocyte implantation seems to be an improvement in joint resurfacing. And the sooner it's done the better because the patients who had the best results had the surgery done early after injury (within the first 18 months). Previous research has shown that patients have up to three years from the time of injury to the time of treatment before it may be too late for a safe and effective repair using these techniques.
Daniel B. F. Saris, MD, PhD, et al. Treatment of Symptomatic Cartilage Defects of the Knee. In The American Journal of Sports Medicine. November 2009. Vol. 37. Suppl. 1. Pp. 10S-19S.
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