Osteochondral Allografts for Focal Cartilage Defects

A focal cartilage defect is a localized area of cartilage damage that affects a specific portion of the joint surface. Unlike widespread arthritis, which involves degeneration throughout the joint, a focal defect is limited to one area. The surrounding cartilage may remain healthy while the injured section becomes damaged or completely worn away.

These defects can vary in size and depth. Some involve only the cartilage surface, while others extend into the underlying bone. Because cartilage has little blood supply, these injuries often do not heal naturally and may worsen over time if left untreated.

Focal cartilage defects can develop from many injuries and conditions. Many occur after a traumatic event that damages the cartilage surface.

Common causes include:

• Sports injuries
• Twisting injuries to the knee
• Direct impact to the joint
• Knee dislocations
• Ligament injuries such as ACL tears
• Meniscus injuries
• Fractures involving the joint surface

Repetitive stress can also contribute to cartilage breakdown over time, especially in athletes who run, jump, cut, or pivot.

Regardless of the cause, cartilage damage can expose the underlying bone, resulting in pain, swelling, catching sensations, and reduced joint function.

An osteochondral allograft is a cartilage restoration procedure that uses healthy donor tissue to replace damaged cartilage and underlying bone within a joint.

The term “osteo” refers to bone, while “chondral” refers to cartilage. An osteochondral allograft therefore contains both healthy cartilage and a small layer of supporting bone.

The donor tissue is carefully matched to the size and shape of the patient’s defect. Once implanted, the graft fills the damaged area with living cartilage and healthy bone, helping restore the joint surface’s normal contour and function.

Unlike some cartilage repair procedures that stimulate the body to form replacement cartilage, osteochondral allografts transplant actual cartilage tissue. This allows surgeons to restore large defects with tissue that closely resembles the patient’s original cartilage.

The goal of an osteochondral allograft is to replace damaged tissue with healthy cartilage and bone.

The graft serves several important functions:

1. First, it restores a smooth joint surface, allowing the bones to move more naturally and reducing friction within the joint.
2. Second, it replaces damaged underlying bone when bone loss is present. This is especially important in larger injuries where both cartilage and bone are affected.
3. Third, it helps distribute forces evenly across the joint. By restoring normal joint mechanics, the procedure may reduce pain and help protect surrounding cartilage from further damage.

Finally, an osteochondral allograft can help preserve the joint and may delay or prevent the need for joint replacement in younger, active patients.

The procedure is commonly performed in the knee but may also be used in other joints, including the ankle and shoulder.

During surgery, Dr. Waterman first identifies and evaluates the damaged area. The surgeon carefully removes the unhealthy cartilage and bone, creating a stable recipient site.

Next, the surgeon prepares a matching graft from donor tissue. The graft is shaped to fit the defect as accurately as possible.

Once prepared, the graft is inserted into the damaged area and secured into position. In many cases, the graft fits tightly enough that additional fixation is not necessary, although screws or other fixation devices may occasionally be used.