Cartilage injury repair and regeneration
Articular cartilage is the smooth surface that covers the bones to create the mobile joints. It is a very specialised tissue which has no real capacity to heal itself if injured. Articular cartilage defects can be caused by trauma or can occur spontaneously. Often over time a defect will progress to osteoarthritis where large parts or the majority of the surface become damaged. (pot holes vs a worn out road surface) If you have an isolated defect of the bearing surface it may be suitable for and require treatment to help the defect to heal.
If the piece of cartilage is still attached to a piece of underlying bone there is a chance it can be fixed back into place, this is normally only possible in children and young adults. The most common initial procedure to heal an isolated cartilage defect in adults is called a microfracture. This involves shaping the defect to create a well contained crater and then penetrating the underlying bone to create a plug of blood and early scar tissue. This plug develops into fibrocartilage (scar cartilage) to heal over the defect. This technique is recommended for small defects (less than 2cm2) and has a good short to mid term track record but the results may taper off beyond 10 years. Microfracture has evolved over the years with the use of additional techniques to improve the healing and long term results into "advanced microfracture". Mr Gallacher normally will use a biological scaffold to help the healing of the cartilage defect similar to the techniques used for ACI but without the cultured cells for small defects.
Defects that do not heal following microfracture or large defects where microfracture is not likely to work may be suitable for more advanced surgical procedures. These include osteochondral grafting where a plug of healthy cartilage is moved from another part of the knee (OATS/mosaicplasty) to fill the defect or autologus chondrocyte implantation which is a form of cell regeneration therapy (ACI or MACI).