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Biologic Joint Replacement
It is far less invasive to do a biologic joint replacement than an artificial joint replacement. Unfortunately, many physicians still think cartilage cannot be repaired. They believe if there is bone-on-bone, artificial joint replacement is the only next step. However, cartilage can be stimulated to produce fibrocartilage repair tissues. Even though these tissues may not have the durability or conformity of normal cartilage, the repair tissue can provide excellent pain relief. If the meniscus is missing, we combine this approach with a minimally invasive meniscus replacement. The two procedures together are known as biologic joint replacement.
Certain candidates are ideal for this procedure. They have localized pain, with cartilage loss in one side of the joint. They also have a strong desire to remain active. We have extended these criteria to patients with more global arthritis when their sporting desires are high and their understanding of the goals of the procedures are clear.
Regrowing Articular Cartilage
Many scientists are working on methods to stimulate articular cartilage repair. Most of the procedures are designed for isolated chondral defects-not osteoarthritis. However, innovations in the field support the basic premise that cartilage repair is possible.
The most common procedure is called microfracture. This involves making holes with a surgical awl into the arthritic bone to stimulate fibrocartilage repair. With mosaicplasty, the surgeon takes plugs of cartilage and bone from an unaffected part of the knee and transplants it to the site of cartilage damage.
Autologous cartilage implants (also called Carticel) takes cartilage cells from the knee in a two-step procedure. First, the cartilage is harvested arthroscopically. The harvested cartilage cells are then grown in culture for several weeks. Next, the physician places the cultured cartilage cells back in the knee, covered with a periosteal flap in open surgery. The procedures are designed to treat focal damage to the articular cartilage surface. While they do not grow normal cartilage, the procedures demonstrate that cartilage cells can grow, dispelling the old concept that cartilage could not be repaired.
In 1991, we designed another procedure, known as articular cartilage paste grafting, to regrow normal cartilage. Currently, this is the only arthroscopic cartilage repair procedure indicated for severely arthritic patients. It is not an experimental treatment and is supported by published, peer-reviewed, long-term studies.
Paste grafting is a single-step, arthroscopic, outpatient procedure. We use the patient's own healthy cartilage, bone and stem cells harvested from the intercondylar notch in the nonweight-bearing area of the femur. The tissue is removed and pounded into a paste in the operating room. We use this paste to repair damaged, arthritic areas of the joint.
In recent cell culture studies of the paste, these undifferentiated cells become chondrogenic when placed in the appropriate media and environment. Paste grafting works for several reasons. New blood supply is brought to the dead arthritic area through fracturing of the surface with an awl. The marrow cells released from the fracture holes and the stem cells contained within the mixture of bone and hyaline cartilage paste differentiate into chondrocytes post-implantation. And the paste, when impacted into the fractured surface, provides a matrix for new cartilage regeneration.
An anabolic, cartilage-friendly environment is created by the new fracture, as opposed to the hostile environment of a degrading arthritic knee. In this environment, cartilage and bone precursor cells produce growth factors that aid the repair process. Additional growth factor injections are under evaluation, which we expect will play an integral role in the biologic joint repair process.
Patients who have had paste grafting for arthritic knees experience pain relief and improved function not just in the first two to five years of follow-up, but also in the nine to 12 years of follow-up.1
In unpublished data, Polish researchers Jaroszewski, Kruczynski and Trzeciak conducted a controlled study to investigate and compare the articular cartilage paste grafting technique to a modified microfracture technique. Full-thickness articular cartilage defects (penetrating through the bone underneath the articular cartilage) were created in the knees of 41 rabbits. Cartilage defects were treated with articular cartilage paste grafting, a modified paste graft technique with periosteal coverage or were left untreated postmicrofracture (control group).
The paste graft treatment group without periosteal coverage demonstrated the best results with the fastest defect filling. In addition, there was more advanced articular surface continuity and defect fill. The results of this study are extremely encouraging and support articular cartilage paste grafting for treating severely arthritic cartilage defects.
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