Treatment of the injury depends on the size, site and depth of the damaged area. Small areas of chondral damage in older patients are not uncommon, and can settle over 6-8 weeks with rest and anti-inflammatory tablets. However, background problems of aching and swelling might persist.
Many acute chondral injuries need to be treated with arthroscopic surgery to either remove or repair the damaged fragment.
In general the only repairable injuries are where there is quite a large chunk of articular cartilage, preferably with a sliver of bone attached (an osteochondral fracture) which can be pinned back in place. There is a good chance of healing in this instance.
In cases where the fragment has to be removed, or where the patients comes long after the injury, you can be faced with pain due to loss of normal articular cartilage covering.
There may be a crater in an important part of the knee with bare bone in the base. It will not heal up with normal joint surface cartilage. It may heal up with fibrocartilage or scar tissue in the base giving some sort of smooth covering. Even if this does happen, there can still be problems, in which case surgery could be needed.
“Microfracture” is the making some small holes in the bone with a sharp pick or small drill. By encouraging bleeding from the bone in the damaged area, a fibrocartilage covering forms. It is thought the blood contains bone marrow stem cells which can help healing. This is not as good as the original articular cartilage but is very effective.
Microfracture is a very useful and simple technique, and can be done as day case keyhole surgery. Depending on the size and site of the microfracture area, crutches might be needed for up to six weeks.
Osteochondral autograft transplantation surgery (OATS)
OATS, also called mosaicplasty, is a technique where we some healthy plugs (cylinders) of bone and articular cartilage from one area of the knee (where it is required less) and put them into the damaged area.
OATS has a role in the treatment of some defects, especially they are deep with bone loss, but generally only in small areas of damage.
Artificial plugs to fill similar areas have been used, but results have been disappointing and research is on-going in this area.
ACI (Autologous chondrocyte implantation)
ACI (Autologous chondrocyte implantation) involves the culture of chondral (articular cartilage) cells removed from your knee, which are then, at a second operation, re-implanted into the defect. Although this sounds like an ideal technique, and has been performed for a number of years, the results have been largely disappointing compared to the high expectations. In many cases biopsies taken after surgery have shown that any new covering is simply scar tissue which has formed in the crater, rather than the desired articular cartilage. Despite the optimism, it is no better than microfracture, requires two operations, and is very expensive.
The reason may be that the cultured cells themselves are simply not healthy enough to create adequate normal joint surface tissue.
What next in joint surface injury?
There is an enormous amount of research going on into treating the damaged joint surface. There is currently no perfect treatment for joint surface injuries, or degenerate damage, and with current technology it is not possible to reliably re-create the normal articular surface.
Stem cells are unspecialised (undifferentiated) cells, which can develop into other cells or tissues. MSCs (mesenchymal stem cells) are stem cells which eventually form cartilage. Much effort is being put into this area, and might be something for the future.
Yorkshire Knee Clinic Surgeons are actively involved in this research.