The Hip, Stem cells and Hip Arthroscopy

Stem cells are often a topic in the popular press and reports often give rise to the idea that a cure for damaged cartilage is just around the corner. The reality is rather different and the challenges remain significant. Our aim in joint preservation surgery of the hip is to identify the abnormality of the shape of the hip that is giving rise to joint injury and thereby pain. The main determining factor in terms of how effective the treatment will be is often the degree of damage to the joint that has already occurred. The main issue relates to damage to the articular cartilage of the joint which is the specialized material that gives our joints their special friction free properties. It is damage to this specialized material that leads to the development of osteoarthritis. Once there is too much cartilage damage in the hip joint then the only solution to deal with the pain coming from the joint is with a hip replacement.

There are a number of techniques that are employed to try and get some degree of cartilage regeneration where the joint is generally in good condition and the area of cartilage damage relatively small. Microfracture is probably the simplest way in which cells can be induced to produce a repair material similar to cartilage. Other techniques are to grow cartilage cells and populate a scaffold which can be fixed into place in a defect. The attraction of stem cells in this scenario is that there are fewer steps involved in the process to try and populate the area with cells to initiate repair. To date, however, there is no available evidence to suggest that this is more successful than microfracture. These cartilage repair techniques are still very much in the research phase, particularly in finding their role in the hip.

The main difficulty is that once the specialized articular cartilage (hyaline cartilage) is damaged, it cannot repair itself to material that has the same amazing properties. Most repair processes produce a rather inferior material that does not have the same wear properties and often shows evidence of degeneration over a rather short period of time.

The key factors in the success of hip joint preservation surgery remain the extent of joint damage in the first place and effective surgery to correct the abnormal shape of the joint so that the forces and stresses on the joint surface are returned to as near normal as possible. Our ability to repair cartilage will certainly improve in the future and stem cells will have their role, but there is still a lot of work to do.