The Cartilage Center

Conditions, Evaluation & Treatment Options

Overview of cartilage and injuries

right knee diagramThere are two types of cartilage in the knee. The meniscus is a cartilage "cushion" between the femur and tibia, one on either side, providing support and suspension and protecting the articular cartilage. Articular cartilage is the Teflon-like coating on the ends of the bones, forming a durable low-friction gliding surface.

Since articular cartilage lacks a blood supply, it is nourished by joint fluid. Once injured, it has limited ability to heal.

Symptoms related to a cartilage injury are variable, and typically only symptomatic conditions require treatment. Symptoms often attributed to a cartilage injury include pain, swelling, clicking or locking, and occasionally a sense of "giving way". These symptoms often interfere with sports participation, and when more severe can even limit activities of daily living.

Some patients with articular cartilage injuries have other related problems affecting the joint. The factors that need to be considered during evaluation and the treatment decision process include: mal-alignment, ligament deficiencies, meniscus deficiencies, and the extent of any related osteoarthritis condition. These issues must be thoroughly identified and properly managed to optimize the environment for articular cartilage repair or transplantation.

Treatments for articular cartilage injuries have advanced over the past two decades, helping patients overcome symptoms, restore function and quality of life, and slowing progression of pre-mature degenerative joint disease. There are several options available, and the best option depends upon the size, depth, and location of the lesion (defect/injured area).

Currently, the most suitable candidates are the young (15 and 55 years) and active. Though the knee is most commonly treated, other joints including the ankle, shoulder, elbow, and hip have been treated as well.

Cartilage injury treatment options


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Microfracture is currently the most commonly performed cartilage repair procedure. Microfracture is a marrow stimulation technique that is used for patients with limited areas of cartilage damage. It involves using chondral picks or drills to make the subchondral bone bleed, and this stimulates "fibrocartilage" to fill in the defect.

It is successful in 75 to 80% of patients who have small, well-contained lesions; a more recent onset of symptoms; and are less than 40 years old.

The post-surgery recovery requires 6 to 8 weeks of partial weight bearing; use of a continuous motion machine; and delay of return to work/sports impact activities for 6 months.

Osteochondral autograft transfer system (OATS)

Osteochondral autograft transfer (OATS) is the transferring of a plug of cartilage and bone into a defect. The donor plug is harvested with a special instrument from a joint surface – typically from a non-weight bearing area of the knee – and transplanted into the defect. The donor plug has been shown to over time to incorporate and cover the edges of the cut area with viable cartilage cells.

The OATS technique was developed in the early 1990’s, and it has seen excellent results for some cartilage surfaces. However, the OATS technique is limited by the size and number of the donor plugs, as well as the size of the defect.

Allograft (cadaver graft) cartilage transplants

Allograft (cadaver graft) cartilage transplants have been utilized with success, especially for large lesions that have associated bone loss. This includes a condition called "osteochondritis dissecans" or OCD, which causes the loss of blood supply to the subchondral bone; and this can put at risk the overlying cartilage. OCD is often seen in patients in their teens or twenties. The fresh osteochondral allografts are acquired through tissue banks, and to match a patient’s size and defect, this can take 6 months or possibly longer. Since the cartilage cells are useable for 4 weeks after the graft becomes available, timing is an issue. To date, most grafts last well up to 10 to 15 years, but then begin to degenerate and fail. High impact sports should be delayed 6-12 months after implantation.

Autologous chondrocyte implantation (ACI)

Autologous chondrocyte implantation (ACI) use a person’s own cultured cartilage cell transplants that were pioneered by Dr. Lars Peterson in Sweden the mid-1980s. Cartilage cells are harvested during a knee arthroscopy, and then sent to Genzyme Biosurgery, which grow the cartilage cells. A sufficient number of cells accumulate over 4 weeks. Then the cells can be stored until a second surgery can be performed.

An open incision is made over the cartilage defect, and 12 million of the cultured cells are injected. A periosteal flap or a biologic matrix is used to cover the defect. The new cells are incorporated and resemble articular cartilage, but the cartilage slowly matures. High impact sports can be resumed 12 to 18 months after surgery, including high-level amateur and professional levels. Improvements are noted in 80 to 85% of patients, and this depends on the location, the biologic environment, and the duration of symptoms.

Joint resurfacing and unicompartmental joint replacements

Joint resurfacing and unicompartmental joint replacements may be used if cartilage repair is not successful. These techniques are often used when there are cartilage defects on both sides of a joint (bipolar lesions) and isolated to one section. Joint resurfacing uses lower profile prosthetic components that spare the meniscus and ligaments and also preserves more bone than a conventional joint replacement.

Am I a candidate for cartilage repair or transplantation?

Cartilage repair and transplantation is a treatment option for young, active and pre-arthritic people experiencing signs of cartilage defects in the knee and other joints. In many cases, alignment, ligament, and/or meniscus problems need to be treated at the same time to optimize the result. Joint resurfacing is a good option for osteoarthritis isolated to a single compartment or as a salvage treatment for failed cartilage repair.