 As a consequence of periacetabular osteotomy the blood flow in acetabulum is decreased. After periacetabular osteotomy has been performed there is fine contact between the osteotomised acetabulum and the rest of the pelvis and the potential for healing is good. However, it has not been investigated how much the blood flow in acetabulum is changed after surgery. The blood flow is considered to be vital for how the pelvis heals after surgery. Most likely, the blood flow is important in relation to which degree osteoarthritis can be prevented after periacetabular osteotomy. 