The smooth white tissue that covers the ends of bones where they come together to form joints is called articular cartilage. It makes our joints easier to move, and allows the bones to glide over each other with very little friction. Cartilage can get damaged by injury or normal wear and tear. Because it does not heal itself well, there are many surgical techniques to stimulate growth of new cartilage and to relieve pain and allow better function. They may also help delay or prevent the onset of arthritis.
Most of these procedures are done arthroscopically with three small puncture incisions around your joint using an arthroscope. Other procedures require the surgeon to have more direct access to the affected area and longer, more open incisions are required. Other times, tears need to be repaired.
The most common procedures for cartilage restoration are:
- Microfracture – damaged cartilage is removed; an awl is used to make holes in the subchondral bones beneath the cartilage; healing response brings new, healthy cartilage cells
- Drilling – like microfracture, stimulates the production of new healthy cartilage. Multiple holes are made through the injured area in the subchondral bone with a surgical drill or wire. The subchondral bone is penetrated to create a healing response. Drilling can be done with an arthroscope.
- Abrasion Arthroplasty – is similar to drilling, but instead of drills or wires, speed burns are used to remove the damaged cartilage and reach the subchondral bone. Abrasion arthroplasty is also done with an arthroscope.
- Autologous Chondrocyte Implantation – is a two-step procedure where new cartilage cells are grown and then implanted in the cartilage defect. First, healthy cartilage is removed with an arthroscope from a non-weight-bearing area of the bone. The tissue that contains healthy cartilage cells is sent to the laboratory to be cultured and increase in number over a three to five week period. Then, in an open surgical procedure called an arthrotomy, the newly grown cells are implanted. The defective area of cartilage is prepared with a layer of bone-lining tissue and sealed with fibrin glue. Then the newly grown cartilage cells are injected into the defect under the new lining tissue.
- Osteochondral Autograft Transplantation – is a procedure used for smaller cartilage defects. Cartilage is transferred from one part of a joint to another. Healthy cartilage tissue, a graft, is taken from an area of the bone that does not carry weight using an arthroscope. The graft is a cylindrical plug of cartilage and subchondral bone. It is then matched to the surface area of the defect and impacted into place, leaving a smooth cartilage in the joint. Sometimes multiple plugs are used, a procedure called a mosaicplasty.
- Osteochondral Allograft Transplantation – if the cartilage defect is too large for an autograft, an open surgical procedure called an allograft may be considered. An allograft is a tissue graft taken from a cadaver donor and is a block of cartilage and bone sterilized and prepared in the laboratory. An allograft is usually larger than an autograft and can be shaped to fit the exact contour of the defect.
After surgery, the joint will be protected while the cartilage heals. Rehabilitation through physical therapy is needed after these procedures to help restore mobility to the affected joint.