Synthetic Scaffold Resurfacing

Originally developed to fill holes from which graft tissue was harvested, synthetic plugs are now also used as graft alternatives. Knee surgeons often recommend them for certain patients because they’re long-lasting and protect the joint from further wear and tear.

  • How it works: Synthetic grafts are engineered to resemble natural ones, with a top layer that mimics cartilage and a bottom layer that mimics bone. The plugs are soaked in a solution of stem cells before being placed in the damaged joint, and the stem cells stimulate the growth of tissue that functions much like normal cartilage and bone.
  • Who might benefit: Normal-weight people younger than 60. Young, active patients tend to have better results.
  • What the experts say: “With these, you can do synthetic OATS and mosaicplasty without damaging another area of the knee,” Dr. Williams says. “[They] allow us to extend the size of the treated area to about 8 millimeters [1/3-inch] square. I’m floored with the clinical results. In younger patients, the return-to-sport rate is about 90 percent.”

Autologous Chondrocyte Implantation (ACI)

Although used in the United States for 15 years, Dr. Williams cautions that only a few surgeons have performed this difficult, two-stage procedure successfully.

  • How it works: In an initial arthro-scopic procedure, surgeons remove a small piece of healthy cartilage from the knee. It is cultured in a lab, producing millions of new cartilage cells (chondrocytes) within weeks. In a second, open surgery, a patch made of collagen or shin tissue is fitted over the damaged cartilage and sealed. The cultured chondrocytes are injected under the patch, and as they mature, they fill in lost tissue with hyaline-like cartilage.
  • Who might benefit: People ages 15 to 50 with a single cartilage defect no larger than 10 centimeters (nearly 4 inches) square in the knee or ankle. ACI may be used off-label to treat other joints and OA.
  • What the experts say: “Initially we thought [ACI] could grow cartilage effectively, but now we’re not so ebullient,” Dr. Williams says. “It can form hyaline-like cartilage with some clinical efficacy, but it’s very expensive, requires two surgeries, has a high re-operation rate and an extended recovery of one year.”