The Case for Articular Cartilage Paste Grafting

Articular Cartilage Paste Grafting (ArtCart) is a technique designed to regrow the bearing surface of joints injured by both trauma and arthritis. Here is the story of its development and the future of arthritis cure.

In 1986, as a Fellow in Orthopaedics with Richard Steadman, I was exposed to the popularization of the microfracture technique, in which arthritic lesions in athletes’ knees are microfractured to stimulate a repair process. While many worked well for a few years, most broke down over time. This was because the cartilage repair tissue was composed mostly of scar or disorganized collagen. To treat these failed microfractures, I developed the articular cartilage paste graft technique from the following observations:

1. The intercondylar notch (where the anterior cruciate ligament passes from the femur to the tibia in the knee joint) was often surgically widened to give the reconstructed graft more room. It almost always grew back over time. I reasoned that if it could grow there, it could grow elsewhere.
2. Articular cartilage was thought to be unable to repair itself—but Richard Weber, PhD, a colleague of mine, demonstrated that the cartilage cells could grow in tissue culture.
3. We observed that the bigger the injury, the more robust the healing response. Large fractures from ski injuries healed better than small, isolated cartilage defects.
4. Marrow cells (we didn’t know they were stem cells in 1991) poured out of the lesions when we supermicrofratured them or morselized the injured or arthritic area of the knee. Essentially, we were taking a dead area of the knee and revitalizing it.
5. Robert Salter, MD, published his findings that motion would direct marrow cells to become cartilage (rather than scar tissue or bone). Following this discovery, a CPM (continuous passive motion machine) was applied to all of the ArtCart-treated lesions.

My team designed and carried out an IRB-approved study of the first 125 patients I treated with the ArtCart procedure. Second-look biopsies were obtained in 72 of the patients and read by an independent musculoskeletal pathologist. It was determined that 1/3rd of the lesions had grown normal articular cartilage, 1/3rd fibrocartilage, and 1/3rd fibrous tissue. We followed those patients and reported on them at various time points over thirty years.

Diagram of the articular cartilage paste graft technique used by Dr. Stone to stimulate cartilage regrowth and healing

As the field of articular cartilage evolved, I published, lectured, and taught seminars on cartilage repair around the world. As we were using the patient’s own tissues, the technique and procedure were free. Yet articular cartilage paste grafting remained only a small part of the surgeon’s armamentarium. Commercial entities brought out competitive implants. Some tried copying our technique, but always skipped key steps and usually failed to improve on our results.

To obtain better results and gain wider adoption, we submitted a grant to the California Institute of Regenerative Medicine. Our study would compare stem cell-augmented paste graft both to paste graft alone and to paste graft augmented by novel hydrogels. The goal is to increase the percentage of normal articular cartilage regeneration from 30% to 80 %. Private donor money to our public nonprofit research foundation www.stoneresearch.org, made studies in rabbits, sheep, and horses possible. (It turns out that horses and dogs suffer from the same cartilage injuries and arthritis and can thus benefit from this technique). We are now midway through this effort, and hope to announce our results in the winter of 2026.

Cartilage injuries and arthritis are, in our view, curable diseases. The research is slow and costly, but the potential benefits are huge. Fifty percent of Americans over age fifty have arthritis, a worldwide disease that produces pain and disability. Since our goal is to allow you to “Play Forever,” we are driven to treat, prevent, and cure arthritis. We are partly there...