is a hereditary bone disorder, where the acetabulum
of the pelvis
joint is deformed. For the joint to function properly, it is neccessary for the acetabelum to cover a large part of the femoral head. Fortunately, the disorder can be corrected by performing an osteotomy
where the acetabelum
is cut free from the pelvis and reattached in a more appropriate location.
Based on my limited knowledge of medical conditions, and lots of pretty pictures, this means that the cup your leg-bone sits in is too shallow, which requires them to cut up your hip-bone and rotate it to properly hold the leg-bone.