Fig. 3

A representative 3D pelvis model and the distribution of 3D displacement of the femoral head centers of the DDH (Crowe I-III) and the healthy controls groups. The distributions (a, b and c) and the standard deviational ellipses (d, e, and f) of 3D displacement of the femoral head centers were shown from the AP, ML, and SI directions. The Crowe classification did not correspond to the degree of the femoral head 3D displacement in patients with DDH. Markers ‘+’ (green),’◊’ (blue),’○’ (yellow), and’□’ (read) represented normal, Crowe type I DDH group, Crowe type II DDH group, and Crowe type III DDH group, respectively