Huw David

Joint Surface (cartilage) Injuries

Most joints in the body are surfaced with hyaline cartilage (as distinct from the fibrocartilage of the menisci). This articular cartilage is very smooth and allows one joint surface to glide upon the other with movement. Like any articulation, the surfaces are likely to wear with time and significant degrees of wear and thinning of the cartilage results in arthritic change. As with baldness in men, thinning of the articular cartilage tends to be diffuse and is not usually amenable to surgery to reverse the trend. More localised areas of cartilage loss or damage may be suited to treatment aimed at either repairing the damage or alternatively promoting scar formation over the damaged area. Unfortunately, hyaline cartilage defects do not heal by the creation of new hyaline cartilage.

A focal area over the surface of the femur may become detached following an injury leaving a “divot” of exposed bone. In the acute setting and in those cases where the fragment is still partially attached, surgery to reposition and secure the fragment, as for example using a screw buried beneath the surface of the bone, may be possible. Less severe cases may involve a crack in the surface, but without detachment and are usually monitored over time with scans to ensure that it heals.

Arthroscopic techniques can be used to stimulate the surface of the bone where there is a focal lesion resulting in a small area devoid of hyaline cartilage. Microfracture involves stimulating blood flow to the area by making multiple small superficial holes in the surface of the bone in order to encourage fibrocartilage (scar) formation over the defect. Transplantation of patches of hyaline cartilage from less important areas of the host knee or from a donor and growth of new cartilage in the laboratory that is then re-implanted into the host joint are newer techniques undergoing evaluation.