Abstract
Introduction
There is many reports about complications with a resurfacing total hip arthroplasty (RHA). One of the most common complications is the femoral neck fracture. A notch and malalignment were risk factors for this. For an accurate implanting the femoral component in RHA, we performed 3D template and made a patient specific template (PST) using 3D printer and applied this technique for a clinical usage. We report a preliminary early result using this novel technique.
material and method
We performed 10 RHAs in nine patients (7 male, 2 female) from June 2009 to March 2010 due to osteonecrosis in 7 hips and secondary osteoarthritis in 3hips with a mean age of 48 years (40-60). We obtained a volumetric data from pre-operative CT and planned using 3D CAD software. Firstly, size of femoral components were decided from the size planning of cups. We aimed a femoral component angle as ten degrees valgus to the neck axis in AP and parallel in lateral view avoiding a notch. We measured femoral shaft axis and femoral neck axis in AP and lateral view using 3D processing software. PSTs were made using Laser Sintering by 3D printer which had the heat tolerance for sterilization in order to insert the femoral guide wire correctly. We operated in postero-lateral approach for all the patients PST has the base (contact part) fit to poterior inter trochanteric area. It has the arm reached from the base and sleeve hole to insert the guide pin into the femoral head. We measured the femoral component angle in three dimensions using the 3D processing software postoperatively. We compared the difference of this angle and the pre-operative planed angles. We also investigated the operation time, the volume of bleeding during operation and complications.
Results
The mean femoral neck angle is 131.9±7.2°. The mean femoral component angle in AP view is 142.5±5.4°. The mean femoral component angle in lateral view is 0.1±1.2°. The mean calculated difference in AP view is 3.5±2.8°. And the mean calculated difference in lateral view is 0.9±0.7°. The mean operation time was 120±25 minutes. The mean volume of bleeding was 401±325ml. No major complication was noted.
Discussion
By planning three-dimensional, it was possible to make an accurate preoperative planning. Though it is a very preliminary report with a small number of cases, we are encouraged to continue this procedure from this data. An application of PST for implanting femoral component in resurfacing THA brought us an accurate implanting as planned. This technique do not prolong an operation time, cost less and can be done with less invasions compared with a navigation system.
