Cartilage Cell Transplant or Microfracture: Which is Better to Repair Knee Cartilage?

New joint-resurfacing techniques are available to treat damage to knee joint cartilage. Without this treatment, the patient is at risk for disability from osteoarthritis. These new methods of cartilage regeneration include mosaicplasty, microfracture (MF), and autologous chondrocyte implantation (ACI).

It's not clear yet which one of these procedures is best. The goal is to promote repair tissue that is as much like the natural articular cartilage as possible. Durability is especially important.

In this study, the results of microfracture were compared with chondrocyte implantation. Quality of regenerated tissue was assessed. Symptoms of pain and stiffness were measured. Other clinical outcomes included activities of daily living, function in sports and recreational activities, and quality of life.

Study design and specific surgical techniques were outlined for the entire study. Chondrocytes (cartilage cells) harvested for growth and expansion in a lab were mixed with ChondroCelect (CC). CC is produced by TiGenix in Belgium. It has the ability to preserve biologic activity of the chondrocytes once they are removed. This makes it possible to multiply the chondrocytes. Using a group of chondrocytes with a specific marker profile improves the ability of the chondrocytes to reproduce.

One year after either MR or ACI surgery, a tissue sample from the repair site was removed and tested. Type of cells, surface area, and thickness of cartilage were measured. Any signs of poor cartilage repair were reported.

Regeneration of the cartilage lining the joint surface was better in the CC implantation (CCI) group. There were also more chondrocytes-like cells. A denser matrix of cells gave the tissue higher compressive strength. This conclusion was based on histopathologic study of the tissues. Scar tissue instead of hyaline-like cartilage was observed more often after MF. Fibrous scar tissue is not as durable as hyaline cartilage.

Clinical outcomes were similar between the two groups. A significant number of patients in both groups reported adverse events. Joint pain and/or swelling were the most common effects. Overall, the CCI group had fewer problems. When there were adverse events in the CCI group, joint swelling and crepitation (crackling sound or feeling in the joint) occurred much more often than in the MF group.

The authors suggest that the use of a product such as CC provides a superior structural regeneration of cartilage tissue. This may lead to better long-term clinical outcomes. Further follow-up of these patients is needed to know for sure what the long-term benefits might be and if the short-term effects are maintained.



References: Daniel B. F. Saris, MD, PhD, et al. Characterized Chondrocyte Implantation Results in Better Structural Repair When Treating Symptomatic Cartilage Defects of the Knee in a Randomized Controlled Trial Versus Microfracture. In The American Journal of Sports Medicine. February 2008. Vol. 36. No. 2. Pp. 235-246.