Purpose: We use a minimally invasive surgical technique (MIS) when performing cementless total hip arthroplasty (THA). Because, it is difficult to put the implant correctly through the small incision, we have used a computed tomography (CT)-based navigation system navigation system since 2005. The current study is a preliminary report of the results.

Materials and Methods : We performed MIS-THA with an antero-lateral approach, in treating 10 osteoarthritis (OA) cases by navigated MIS-THA (Navi group) and compared them with the 10 OA cases treated without navigation (non-Navi group). Follow-up periods ranged from 6–9 months. All of the implants were AMS HA cup with a PerFix stem. The patient’s preoperative CT data in DICOM format was used in the work station for preoperative planning. Appropriate angle and the positions of cup and stem were decided preoperatively on the 3D model of pelvis and femur. The factors evaluated were operation time, blood loss, the inclination and the cup anteversion angle on post operative radiographs and CT images.

Results: The mean operation time and mean amount of blood loss were 110 minutes versus 80 minutes, and 417 ml versus 260 ml in the Navi and the non-Navi groups, respectively. The differences were significant. The differences between the planned and postoperative angles were lower in the Navi group than in the non-Navi group. However, the differences between the groups were not significant. There were no major complications, nerve palsy, or fracture in either group.

Conclusion: Our findings were similar to previous reports. The increase of operation time and the amount of blood loss were caused by lengthy registration and adjustments to the system. Although the navigation system increased implantation accuracy, improvements are necessary to reduce blood loss and operation time.