Safety and Accuracy of Ct-Based Navigation for Rotational Acetabular Osteotomy

Background: Although there are several clinical reports of the accuracy and safety of navigation for total hip arthroplasty, there have been few clinical reports on navigation for rotational acetabular osteotomy (RAO). The purpose of this study was to evaluate clinically the safety and accuracy of CT-based navigation for RAO. Method: We retrospectively reviewed consecutive 36 hips of 29 cases with symptomatic hip dysplasia who underwent RAO using the CTbased navigation between July 1999 and September 2009. Results: All patients were female. The average age at operation was 31years with a range of 17 to 48 years. Radiographic measurements showed the level of the osteotomy from the articular surface ranged from 15 mm to 20 mm with an average of 16 mm ± 1.3 mm (SD). No fragmentation or crack of the acetabulum due to intra-articular osteotome perforation was identified. The average center-edge angle improved significantly from 1° on preoperative radiographs to 34° on the immediate postoperative radiographs (p ＜ 0.001). All patients were followed-up for a minimum of five years with an average follow-up term of eight years (range, 5 to 15 years). There were no complications such as infection, nonunion, avascular necrosis or neuro-vascular injuries. The Merle d’Aubigne and Postel hip score improved from 13.7 preoperatively to 16.9 at the latest follow-up. Radiographically, progression of the joint space narrowing was found in one hip. The remaining cases showed no progression of osteoarthritis. No hip was converted to total hip arthroplasty. Conclusion: CT-based navigation for RAO is safe and accurate with substantial clinical improvement in patients with hip dysplasia.