Placement of the acetabular cup in accurate and optimal position is important in total hip arthroplasty (THA) to obtain satisfactory result. On the other hand, inaccurate manual cup placement with conventional cup placement guide was reported. We therefore have been applied the mechanical acetabular alignment guide for accurate cup placement. The purpose of this study was to validate the accuracy of the acetabular alignment guide for total hip arthroplasty. Between 2003 and 2014, 52 primary THAs were performed in 48 patients with using the acetabular alignment guide by one surgeon (HT). There were 42 female and 6 male with a mean age at operation of 71.1 years old (47 to 91). The original diagnosis were osteoarthritis in 43 patients (46 hips), and avascular necrosis of femoral head in 5 patients (6 hips). Used acetabular implants were Stryker® Trident AD HA cup in 24 hips and Wright medical® Acetabular Cup System in 28 hips. After completion of anesthesia, half pins were inserted at the both anterior superior iliac spine vertically and the frame was attached to the pins horizontally in supine position. Then, the patients were placed in lateral decubitus position. Finally, the alignment rod, which indicated the optimal direction of the cup (abduction angle 40°, ante-version angle 20°), was connected to the frame. All operations were done by postero-lateral approach. Assessment of the cup abduction angle and ante-version angle was performed by Lewinnek's method using postoperative AP radiograph in supine position.Purpose
Materials and methods
