The articular cartilage (lining of the knee joint) can be damaged by either an acute injury or repetitive wear and tear. Articular cartilage has very poor potential to repair itself once it has been damaged. There are a number of surgical options available to treat areas of cartilage damage. The most commonly carried out procedure is a chondroplasty.
This term covers a number of simple techniques aimed at reshaping and smoothing-off of any areas of damage to the articular cartilage. Chondroplasty involves removing loose flaps of cartilage (this can cause a sensation of catching and pain in the knee). Micro-instruments are inserted into the knee and used to take away any loose fragments of articular cartilage and stabilise the remaining tissue. This procedure is reserved for small, shallow cartilage defects.
This procedure is reserved for more significant areas of joint surface damage where the lesion is full thickness and down to the underlying bone. Microfracture leads to the formation of new joint surface cartilage. The damaged area is debrided and then the underlying bone is punctured with a micro-instrument or pick. This allows bleeding from the bone. The resulting blood clot fills the cartilage defect. The blood clot contains specialised cells which have the potential to transform into new cartilage. To allow the microfracture to work, patients are required to use crutches for 6 weeks following surgery and then have a gradual return to sport depending on the size and position of the lesion.
Cartilage transplantation or MACI
MACI stands for Matrix-induced Autologous Chondrocyte Implantation. The technique involves an initial arthroscopy or key-hole procedure during which a very small amount of the patient's articular cartilage is taken from a specific area within the knee. The retrieved cartilage is then grown in a laboratory to produce millions of cartilage cells which are attached to a "matrix" made of collagen. A second procedure is then carried out to expose the damaged area and the new cartilage cells are re-implanted. A careful post-operative rehabilitation programme is then followed to ensure the best result ( see below ).
Rehabilitation protocol for MACI surgery