Arthritis Today

The Future of Joint Repair

Promising new therapies regenerate cartilage to repair joints.


Elite athletes, including Tiger Woods, Kobe Bryant, Alex Rodriguez and Dara Torres, are using unconventional treatments with high-tech names to heal their worn-out or injured joints. Most of these therapies try to harness the body’s healing power to repair damaged cartilage.

Cartilage restoration bridges the gap between symptom relief and joint replacement surgery, says orthopaedic surgeon Jason M. Scopp, MD, director of the Joint Preservation Center at Peninsula Orthopaedic Associates in Salisbury, MD.

“When cartilage damage occurs, you no longer have a smooth relationship between the bones in the joint. It’s like driving over a pothole in your car,” he says. “In cartilage repair, we’re filling in the pothole so it doesn’t get larger.”

But the procedures aren’t for everyone. Orthopaedic surgeon Brian J. Cole, MD, head of the Cartilage Restoration Center at Rush University Medical Center in Chicago, stresses they’re not intended for patients with bone-on-bone osteoarthritis (OA). However, he adds, “They may prevent or forestall arthritis in the future.”

Some techniques have been around for decades, while others are not yet approved in the United States. We asked experts to help separate the science from the hype.


Microfracture, an older technique, is still widely used for cartilage repair, but is often being replaced by procedures that last longer and can restore – rather than repair – cartilage.

How it works: Surgeons clean and smooth the cartilage tear’s edges and pierce holes in underlying bone, forming a blood clot rich in stem cells and growth factors. Over time, the clot remodels into fibrocartilage, which is less supple and durable than the original, hyaline cartilage.

Who might benefit: Normal-weight people ages 15 to 50. Patients younger than 40 with defects smaller than 4 centimeters (about 1.5 inches) square have the best outcomes.

Expert opinion: “It’s not very durable after five years,” says orthopaedic surgeon Riley J. Williams III, MD, director of the Institute for Cartilage Repair at the Hospital for Special Surgery in New York. “It’s not the most effective treatment, but it’s easy to do and inexpensive.”

Osteochondral Autograft or Allograft Transfer System (OATS)

OATS restores hyaline cartilage.

How it works: In the autograft procedure, surgeons transfer a small plug of cartilage and bone from a healthy area of the patient’s knee to a damaged area. (Transplanting several small plugs is called mosaicplasty.) For larger areas, doctors may use allografts, or donated tissue.

Who might benefit: Autografts are best for active people ages 15 to 50 with small, distinct areas of damage. Allografts can also ease pain and delay progression in some people with OA.

Expert opinion: “It’s costly, but better long-term than microfracture,” says Dr. Scopp.

Synthetic Scaffold Resurfacing

These synthetic, long-lasting plugs are used as graft alternatives.

How it works: Synthetic grafts are soaked in a stem-cell solution before surgeons place them in the damaged joint, where they stimulate tissue growth.

Who might benefit: Normal-weight people younger than 60. Young, active patients often have better results.

Expert opinion: OATS using synthetic materials doesn’t damage surrounding knee cartilage and bone, allowing surgeons to treat larger areas, says Dr. Williams.

Autologous Chondrocyte Implantation (ACI)

This two-stage procedure restores hyaline cartilage.

How it works: Surgeons first arthroscopically remove a small piece of healthy cartilage from the patient’s knee and culture it, producing millions of new cartilage cells. In a second, open surgery six to eight weeks later surgeons fit and seal a collagen patch over damaged cartilage, then inject cultured cells. As cells mature, they fill in lost tissue with hyaline-like cartilage.  Matrix ACI is a less invasive, second-generation procedure that allows surgeons to skip the patch step and has a shorter recovery. It’s approved for use in Europe and under study in the United States.

Who might benefit: People ages 15 to 50 with a single cartilage defect no larger than 10 centimeters (nearly 4 inches) square. ACI can also be used to treat OA.

Expert opinion: It can effectively form hyaline-like cartilage, but is expensive and has a high re-operation rate and an extended recovery, Dr. Williams says.

Autologous Cartilage Tissue Implants

Autologous cartilage tissue implants use a combination of cell therapy and tissue engineering techniques. The first of these second-generation methods could be approved in the United States in a few years.  

How they work: Bio-engineered implants made with the patient’s cartilage cells are grown outside the body. Methods vary, but a common approach is culturing cartilage cells and seeding them onto a biodegradable scaffold, where they grow and produce cartilage before the implant is placed in the joint.

Who might benefit: People ages 18 to 55 who have a large cartilage defect in the knee.

Expert opinion: Dr. Williams notes his study of an experimental implant showed it significantly outperformed microfracture at two years.

Stem Cells

Mesenchymal stem cells (MSCs) from bone marrow can become cartilage cells, and have much promise as a treatment for regenerating bone. Stem cells and bone marrow trick the body into healing more completely and efficiently, says Dr. Cole.

Many stem cell procedures are available internationally, but the FDA currently limits how they are used in the United States.

How it works: Researchers are studying many stem cell techniques. One involves injecting or implanting the patient’s bone marrow concentrate, a rich source of stem cells and growth factors, into damaged areas.

Who might benefit: Some researchers think stem cells have the best long-term potential for repairing OA-related cartilage damage.

Expert opinion: “It’s significantly less expensive [than other methods] and shows promising results in both animal and human models,” say Dr. Scopp.

Platelet-Rich Plasma (PRP)

Several studies found PRP is safe and effective for cartilage tears and relief of OA-related knee pain. PRP is widely available in the United States.

How it works: A doctor draws the patient’s blood, separates out platelets, concentrates them and injects the growth-factor rich solution into damaged areas, where they reduce inflammation and promote tissue repair.

Who might benefit: Younger people with acute and chronic sports injuries as well as those with localized areas of OA.

Expert opinion: PRP isn’t covered by insurance, so patients pay the entire cost, which ranges from $500 to $5,000 per treatment, says Dr. Scopp.