Dr Tan Chyn Hong, orthopaedic surgeon at Mount Elizabeth Novena Hospital, explains the treatments available to repair or regenerate damaged cartilage.
Cartilage is essentially a white shiny material that helps cushion and cover the area where the bones meet the joints. It serves as a lubricating surface as well as a shock absorber. Cartilage damage can be seen as a hole or crater on the otherwise smooth surface of the joint. If left untreated, the joint can become stiff, swollen and painful. It may even progress to a stage that requires a total joint replacement with metal and plastic components.
Cartilage regeneration is a procedure that attempts to restore damaged cartilage by harnessing the body's cells to regrow or replace lost cartilage.
Most of these treatments can be done by arthroscopy (more commonly known as keyhole surgery), providing benefits of less pain, less bleeding, and faster recovery. However, some injuries will still require a traditional open incision technique where a bigger cut is made to expose the cartilage damage.
For the less severely damaged cartilage, all that is needed is a 'clean up' procedure. During this procedure, a video camera is inserted through a small incision and saline is introduced to wash out the joint. Washout expels any loose debris. Debridement involves removing the damaged cartilage, and this is often performed concurrently with the washout.
Microfracture is a surgical procedure to treat areas of damaged cartilage. It is done to stimulate the growth of new cartilage in patients with a small area of damaged cartilage. The procedure is often performed inside the knee joint, but may also be used to treat other joints such as, the hip, ankle, and shoulder.
For injuries smaller than 2cm2, microfracture is the recommended procedure. It involves puncturing small holes in the hard interface between the cartilage and the underlying bone to create channels for the bone marrow cells to surface and fill the crater. The small holes form a blood clot rich in stem cells and eventually remodels into fibrocartilage. Fibrocartilage is a tough, dense and elastic material that helps fill in the torn part of the cartilage, hence repairing the lesion.
ACI is most often recommended for younger patients who have single defects larger than 2cm2. This is a 2-step procedure that takes several weeks to complete. The first procedure involves extracting healthy cartilage cells from a non-weight bearing area of the knee through minimally invasive surgery. The cells are then cloned and grown in the laboratory for 6 – 8 weeks. Thereafter, a surgical procedure is done to implant the newly grown cells into the damaged area.
This is a 2-step procedure that repairs the articular cartilage damage by using the patient's own cultured cartilage cells. The first step is similar to that in ACI where healthy cartilage cells are extracted from a non-weight bearing area of the knee. The cells are then cultivated on a membrane. Several weeks later, the membrane is placed into the defect. This helps the cartilage regenerate.
Articular cartilage is the smooth, white tissue that covers the ends of bones where they come together to form joints. The presence of cartilage in the joints helps in movement and allows bones to glide over each other with little friction. Daily wear and tear or an injury may result in damage to the articular cartilage.
In this 1-step procedure, the surgeon harvests a 'plug' of healthy tissue and bone from an unaffected, non-weight bearing area of the patient's own joint. The new graft is transferred to replace the damage area. When multiple 'plugs' are used, the result is like a mosaic pattern, hence the term mosaicplasty.
Stem cells, or more accurately mesenchymal stem cells (MSC) have been used in a research setting to repair and regenerate cartilage damage. MSCs are found in multiple human adult tissues including bone marrow and adipose tissues. They have the ability to differentiate into bone, cartilage, muscle, and adipose tissue. Human clinical trials have been published showing promising results but long term studies are needed before it can be utilised routinely in the normal clinical setting.
After the cartilage repair procedure, there is usually a period (6 – 8 weeks) during which the patient is required to use crutches. This is to reduce pressure on the healing cartilage. The time taken for complete recovery could be up to 3 – 6 months.