Autologous Chondrocyte Implantation (ACI) is a technique that aims to repair damaged cartilage in a joint. The knee joint is most commonly treated with this technique. Cartilage Cells (chondrocytes) are taken from the knee and multiplied in culture to increase the number of cells. When there are enough cells available, these cells are implanted back into the knee to repair the area of cartilage damage.


The first procedure is usually an arthroscopy, (key-hole surgery) to collect cartilage, which is then sent to the laboratory for the cartilage cells (chondrocytes) to be prepared. (see cell culture ) Some blood is taken from you, and from this sample serum is prepared. The serum contains nutrients and growth factors, which helps the cells to grow.


Stage II involves a more major operation.Knee - defects of cartilage onlyThe joint is opened through an incision at the front of the knee. The cartilage defect is debrided (tidied up) and all loose bits of tissue are removed. A patch of periosteum is usually taken through a separate incision on the shin. The periosteum is the outer lining of the bone and is used to make a patch that is fixed to the defect. Very fine stitches are used to hold the periosteum to the defect and tissue "glue" may be used to make the patch watertight.


The knee cap has a joint that forms part of the knee and has to be carefully assessed for alignment. If condrocyte implantation is undertaken with bad alignment then the new cartilage will wear as fast as the old. Various techniques are used depending on what is needed. The patellar tendon may need to be moved, or the medial patello-femoral ligament reconstructed. A new method of reconstructing the medial ligament developed at Oswestry appears to be very effective.


Good exposure is key to success in the ankle and either the bone on the inside or the outside of the ankle is divided to allow access. Bone loss is common and is debrided and plugged with a piece of your own bone. A layer of periosteum or chondrogide is then used to repair the defect. Another option preferred by some surgeons at Oswestry is to treat the defect by keyhole surgery. After careful debridemet of cartilage and bone as necessary, air is put in the joint. Chondrocytes are added to a collagen membrane and inserted with a fibrin sealant.


An anterior approach to the hip allows the femoral head to be dislocated carefully. Similar steps to the knee then are used either to remove unstable cartilage and debride the base of the cartilage base. If there is an area of avascular necrosis or dead bone then this is best drilled out and plugged in the OsPlug procedure. Again a membrane is stitched over, tested for cell leakage and cells inserted. The hip is reduced into the socket and the muscle sutured back in place.