The MACI operation

In this procedure a small sample of tissue is taken from a healthy part of the knee articular cartilage, cartilage cells (chondrocytes) are collected from this sample and multiplied in a laboratory over a period of weeks to increase the number of cells. The cells are then seeded on a synthetic membrane made from collagen and the membrane is then implanted into the defect to repair it.

Operation 1:

Fig 1. – Arthroscopy (keyhole surgery) to take a sample of cartilage (biopsy) from the non-weight bearing part of the joint surfaces.

This biopsy will contain the cartilage producing cells known as the chondrocytes.
This biopsy is sent to a laboratory where the cells are grown over a period of 3-4 weeks generating about 15-20 million cells. These cells are then placed on a membrane ready for implantation.

Operation 2:

Fig 2. 6 – 8 weeks after the initial arthroscopy. This involves and open operation with a vertical incision on the inner or the outer side of the knee to expose the area of damaged cartilage.

Fig 3. The damaged area of cartilage is cut away and prepared for implantation of the new graft.

Fig 4. The membrane with seeded new chondrocytes is then cut to size and fibrin glue is placed in the base of the prepared area.

Fig 5. The membrane with the chondrocytes is glued in place over the defective area using fibrin glue, which later incorporates into the membrane and growing layer of cells without causing damage.

Full details of the procedure are contained in the information booklet produced by GENZYME UK. (www.maci.com)