抄録
Objective: Total hip arthroplasty for degenerative arthritis secondary to developmental dysplasia of the hip (DDH) remains a challenging task, and the difficulty of the procedure varies depending on the severity of the modified anatomy of the proximal femur and acetabulum. The most severe anatomical abnormality is a completely dislocated hip. In this study, we report the position of the femoral head in patients presenting with a completely dislocated hip.
Methods: Between 2007 and 2009, we performed 47 consecutive total hip arthroplasties for completely dislocated hips in 41 patients following DDH. Six patients had bilateral completely dislocated hips. On anteroposterior radiographs in the supine position, a line was drawn through the teardrops, and then a perpendicular line was drawn from the greater trochanter to that line. In addition, these lines and teardrops were used as the base. The vertical, horizontal, and direct distances of the proximal tip of the greater trochanter to were measured.
Results: Body height and weight correlated with the horizontal distance (r = 0.33, p = 0.033; r = 0.38, p = 0.013, respectively). However, no significant correlation was observed between the vertical and direct distances and the subject's height and weight. There were significant differences in the vertical and direct distances between patients with bilateral completely dislocated hips and patients with lateral completely dislocated hips (p = 0.044, p = 0.037, respectively).
Conclusion: Total hip arthroplasty for a completely dislocated hip following DDH has some surgical pitfalls. One of the most important problems concerns the subtrochanteric osteotomy. There is currently no methodology for definitively determining the final limb length and the amount of bone that should be resected. In addition, no data are presently available regarding the position of the femoral head in completely dislocated hips. This is the first report about the femur position in completely dislocated hips. A large and detailed series elucidating the position of the femoral head is therefore needed to confirm the safety and efficacy of the surgery performed on these patients.
