Tuesday, December 4, 2007

In the past 20 years, researchers and surgeons have made advances in repairing and restoring knee cartilage, but no foolproof method exists. Options for cartilage repair include:

Shaving or Debridement: One of the most common treatments for cartilage defects that have not worn to the bone. Using a pencil-thin instrument called an arthroscope inserted into the knee through a small incision, a surgeon shaves and smooths shredded or frayed cartilage. Debridement is often used in combination with the other treatments. Because the technique doesn't fix underlying causes of injury, symptoms may return.

Success rate*: 75 percent

Microfracture or Abrasion: Common for patients with cartilage damage all the way to the bone. Surgeons use arthroscopic tools to scrape the damaged area and create bleeding of the bone. Small holes are then picked into the defect, allowing blood vessels and bone marrow cells to come in contact with the injury. Bone marrow fills the defect, which eventually matures into scar cartilage. Often used as a first-line technique.

Advantages: Surgery is performed arthroscopically. Relatively fast recovery (six to nine months) and cost-effective.

Disadvantages: According to Kai Mithoefer, clinical instructor of orthopedics at Harvard Medical School and author of several landmark studies on cartilage repair, 40 to 70 percent of patients have decreasing knee function after an initial increase, and the surgery has unpredictable results for larger defects.

Success rate: 65 to 80 percent.

Autologous Chondrocyte Implantation (ACI): Cartilage cells are arthoscopically removed from the injured knee and grown outside the body in a tissue culture. After about four weeks, the cells are implanted into the defect. Over time, the cells grow to fill the defect with a new cartilage surface. Generally recommended for defects over 200 millimeters when there is no cartilage wear around the defect.

Advantages: Many researchers say the technique produces normal hyaline cartilage. It's often used after other techniques have failed and has good durability.

Disadvantages: Requires large incisions, a two-stage technique, has a slow recovery (12 to 18 months) and is expensive.

Success rate: 70 to 90 percent.

Osteochondral Autograft Transfer (OATS): Surgeons take a plug of the patient's cartilage from a part of the knee that does not bear weight during walking and transplant it into the injured part of the knee.

Advantages: Normal hyaline cartilage is used, with a relatively short recovery (four to eight months). Relatively cost-effective, and long-term durability is good.

Disadvantages: The surgery is best for fixing smaller defects (less than 4 centimeters). Norman Marcus, a Springfield orthopedic surgeon who performs several types of cartilage repair surgeries, describes this as "robbing Peter to pay Paul."

Success rate: 75 to 95 percent up to 10 years.

Osteochondral Allograft Transplantation: Surgeons take a plug of cartilage from a cadaver.

Advantages: Preferred for deep, large defects.

Disadvantages: Large incision necessary, potential for disease transmission from cadaver tissue, cartilage cells must be transferred quickly from cadavers, long waiting times for tissue, high cost, declining success rate over time and slow recovery (more than 12 months).

Success rate: 95 percent after five years, 71 percent after 10 years, 66 percent after 20 years.

-- Elizabeth Agnvall

SOURCES: Success rates and other details from Kai Mithoefer.

* Surgical success rates generally reflect improvement in pain and activity levels.