Cartilage replacement is a surgical procedure performed in an attempt to replace worn out cartilage with a new cartilaginous covering. It is usually performed to treat patients with small areas of cartilage damage usually caused by sports or traumatic injuries. It is not indicated for patients who have advanced arthritis of knee. Articular or ‘hyaline’ cartilage is the tissue that covers the surfaces of the knee joint which allows ‘smooth’ interaction between the two bones of the knee joint. It has minimal capacity to repair itself because there is no direct blood supply to hyaline cartilage.
Cartilage replacement is performed in an attempt to relieve pain, restore more normal function, and hopefully delay or prevent the onset of arthritis. The goal of cartilage replacement procedures is to stimulate growth of new hyaline cartilage. Various procedures used in cartilage replacement include:
- Microfracture: Microfracture involves creating numerous tiny holes in the injured joint surface using a special tool, called an ‘awl’. The holes are made in the bone underlying the cartilage (subchondral bone). This stimulates a healing response designed to encourage the formation of a new cartilaginous layer covering the exposed bone.
- Subchondral Drilling: This procedure is similar to microfracture where multiple holes are created in the injured joint area using a surgical drill or wires.
- Abrasion Condroplasty: This procedure is similar to drilling but involves use of high speed (1500-2500rpm) shaving devices to remove the damaged cartilage.
- Autologous Chondrocyte Implantation (ACI) – This is a two-step procedure, where healthy cartilage cells are removed from non-weight bearing areas of the joint, cultured in the laboratory and then implanted into the cartilage defect during the second procedure. During this procedure, a patch may be harvested from the periosteum, a layer of thick tissue that covers the bone and is sewn over the damaged area using fibrin glue. The new cartilage cells are then injected under the periosteum, into the cartilage defect to allow the growth of new cartilage. This procedure has recently been restricted by the National Institute for Clinical Excellence (NICE).
- Osteochondral Autograft Transplantation System (OATS): In this procedure, plugs of cartilage and bone are taken from a non-weight bearing area of the knee in the same individual and transferred to the damaged areas of the joint. This method can be used to treat small – moderate cartilage defects.
- Following cartilage replacement surgery, your surgeon may well recommend physiotherapy to help restore mobility to the affected joint.