I've heard of arthroscopy done for shoulders and knees, but never for hips. Why is that?
Arthroscopies are usually done for the knees and shoulders because of the way the joints are formed - they are easier to access with the small instruments used. However, the procedure is done on other joints, such as the hips, as surgeons learn the best ways to do them and for what reasons.

A small study done recently found that patients with certain types of hip problems did benefit from arthroscopies in helping determine their diagnosis and treatment.