Articular cartilage is the firm, smooth covering on the ends of bones where they contact other bones to form an articulating joint such as the knee. Together with the thick synovial fluid within the joint, articular cartilage forms a surface that allows low friction movement and assists as a shock absorbing tissue, distributing loads around the joint when walking or running.
Chondrocytes (articular cartilage cells) build articular cartilage by forming a matrix (a complex combination of proteins and water). When articular cartilage is damaged, it does not repair itself effectively like other tissues. Consequently injury can lead to increasing joint pain and reduction in joint movement and can also lead to degenerative change or osteoarthritis (slow degeneration of articular cartilage).
Autologous Chondrocyte Implantation (ACI) is a process whereby articular cartilage cells (chondrocytes) are collected, multiplied in a laboratory to increase cell number and then re-implanted (after approximately 4 weeks) with a special surgical technique into the damaged area of the knee. This would allow cell growth and cartilage repair to occur producing new, durable cartilage.
ACI is suitable for treating cartilage damage caused by direct injury (e.g. sports injuries, car accidents, falls) where the damaged area is surrounded by normal healthy cartilage. Widespread cartilage damage (osteoarthritis) or inflammatory disease ( rheumatoid arthritis) is not suitable for this treatment. Your specialist surgeon will advise you whether ACI is suitable for your condition.
This procedure is indicated for those patients who have an isolated full thickness articular cartilage defect in the knee, which is causing symptoms such as pain and clicking. This injury is generally from an acute injury, but can also occur over time, due to repeated injuries. The knee is generally swollen and pain is located over the site of the cartilage injury. It is not a suitable procedure for established osteoarthritis as yet.
The procedure involves taking a biopsy (sample) of the healthy cartilage from the knee through an arthroscopy (keyhole surgery). The size of the defect will also be assessed at this time. The cartilage biopsy is processed in a laboratory where the cartilage cells will be cultivated in a matrix and this takes approximately four to six weeks. Once the matrix or cartilage is ready, it will then be re-implanted. The re-implantation occurs through an arthrotomy where the joint is opened through a small incision to allow accurate placement of the cartilage graft.
After a thorough clinical assessment of the joint, the patient will generally have plain X-rays and an MRI scan of the knee to help accurately assess the location and size of the cartilage defect. At times, the patient may have previously had an arthroscopy. A range of motion brace will be organised prior to the surgery and this will restrict the joint movement and protect the cartilage graft.
The hospital will contact you on the day prior to your surgery to advise you of your admission time. You will also be instructed not to eat or drink anything from midnight the night before your surgery until the surgery has been completed.
The initial arthroscopy for the biopsy is preformed as a day surgery procedure.
The implantation surgery requires a hospital stay of two to three days.
A special rehabilitation program needs to be followed following the implantation of cells. This involves bracing of the knee and a gradual return to full weight bearing. It is vital that the rehabilitation protocol given by the surgeon is followed closely to maximise the benefit of the operation.
International studies show that with the use of cartilage culture and implantation, about 85% of patients are significantly improved, many returning to full, normal pain free activity. The results of cartilage cell implantation are substantially better than those of previous treatments.
The total cost of the operation depends upon the type of private health insurance the patient has. For the cell implant, there are no out of pocket costs to patients with private health insurance, and for approved compensable patients e.g. Workers compensation.