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CARTILAGE TRANSPLANT REPAIRS INJURED KNEES FOR THOUSANDS LESS THAN SWEDISH PROCEDURE

Seven-year Study Shows Cartilage Regeneration With Outpatient Surgery

NEW ORLEANS and SAN FRANCISCO, March 17, 1998 — A novel cartilage-transplant technique, performed on an out-patient basis, was shown to repair injured and arthritic knee joints, in a study presented today at the annual meeting of the Orthopaedic Research Society in New Orleans. In contrast to the so-called "Swedish Method," which involves two surgical procedures to remove and later implant a patient's own cartilage cells, the new surgery does not require cells to be grown outside the body, resulting in potential cost savings of more than $50,000 per patient and decreased risk to the patient.

Kevin R. Stone, M.D., orthopaedic surgeon and chairman of The Stone Foundation for Sports Medicine and Arthritis Research at The Stone Clinic in San Francisco, presented the results of a seven-year study showing a patient's own cartilage cells can be transplanted from a healthy, non-weight-bearing area of the knee to the damaged knee joint in a single, outpatient arthroscopic procedure performed under local anesthesia. The new cartilage regenerates into healthy cartilage, the smooth type that covers the ends of the thigh (femur) and shin (tibia) bones that form the knee joint.

The new technique obviates the costly need for growing the patient's cartilage cells in a growth medium outside the body, followed by a second surgery several weeks later to transplant the cells. The two-step surgical procedure and cell-culturing process can cost more than $60,000, with the cost currently not reimbursable by most U.S. health care providers. Used by a growing number of surgeons in the United States and Europe, the new surgery can be performed at an average of one-tenth the cost of the Swedish procedure.

"The study shows that both hyaline-like articular cartilage and fibrocartilage can regenerate well within the knee joint, and there appears to be no prerequisite to grow the cells in tissue culture prior to transplantation," said Dr. Stone.

Since 1991, 89 patients (59 males and 30 females) have undergone the procedure, called Articular Cartilage Autografting. Among the most significant findings was a substantial reduction in the pain felt by 38 of 40 patients with more than one year of follow-up. All patients had follow-up exams, with the longest follow-up of 75 months.

One-Step Cartilage Transplantation

The single-step surgery is aimed at encouraging the patient's body to heal itself. Under local anesthesia, using special surgical tools and an arthroscope (a video-aided instrument to conduct joint surgery through a small opening in the skin), the surgeon takes a small amount of cartilage and porous bone from a healthy location on the femur — the leg bone that extends from the hip to the knee joint.

The cartilage and bone sample is "morselized" into a mortar-like paste that is grafted onto the damaged knee-joint's surface. The mixture contains cartilage matrix and natural growth factors that act to stimulate cartilage regeneration at the defect site. Patients are kept non-weight bearing for four weeks, and are instructed to use a continuous passive-motion machine for six hours each night.

Follow-up studies showed new cartilage had re-grown into the damaged area. "The regenerated cartilage is a mixture of fibrocartilage and hyaline-like cartilage," explained Dr. Stone. "This new cartilage is as good as, or better than, any other histology we have seen from any other study of human knee joints."

Articular Cartilage Injuries Common

Unlike bone or skin, cartilage is normally unable to repair itself. This problem has limited the complete recuperation from serious injuries involving knees, as well as ankles, shoulders and other major joints. Each year, more than 500,000 joint repair procedures and total joint replacements are performed in the United States, including about 95,000 total knee replacements and 41,000 other procedures to repair defects of the knee. One of the most common knee defects — often the result of traumatic sports injuries — involves damage to the articular cartilage within the knee joint.

Full-thickness defects of articular cartilage, involving both cartilage and underlying bone in the knee, may progress to osteoarthritis. When osteoarthritis is severe, the usual treatment is replacement of the arthritic articular surface with an artificial prosthesis, commonly performed in people over 60 years of age. Because prostheses have a limited lifetime, total knee replacement in younger patients is problematic. Promising a delay in the need for total knee replacement for some patients, transplantation of articular cartilage is a potential treatment for damaged cartilage.

This research is supported by The Stone Foundation for Sports Medicine and Arthritis Research, a non-profit organization that conducts research in advanced surgical techniques for orthopaedic sports medicine. These efforts have led to improvements in cartilage replacement and regeneration, cruciate ligament repair and reconstruction, and techniques to prevent osteoarthritic degeneration.

ARTICULAR CARTILAGE AUTOGRAFTING

Fig. 1 — First step of articular cartilage transplantation involves shaving the articular cartilage lesion.

Fig. 2 — Microfracture preparation of the base of a chondral lesion prior to articular cartilage grafting.

ARTICULAR CARTILAGE AUTOGRAFTNG

Fig. 3 — Harvesting of cartilage and cancellous bone from the intercondyle notch.

Fig. 4 — Transplantation of the articular cartilage and cancellous bone graft to the prepared chondral defect.

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