Application of a CT-3D fluoroscopy matching navigation system to the pelvic and femoral regions.

Objective: The aim of this study was to find the proper location of the fluoroscopic imaging center in order to apply a CT-based 3D fluoroscopy matching navigation system in the pelvic and femoral regions.

Materials and methods: To simulate surgeries around the hip joint, a dry human pelvis and femur were used. A total of 16 fiducial markers, each consisting of a metal ball 1.5 mm in diameter, were fixed to the pelvis and femur. For the pelvis, the pubic symphysis, the acetabular fossa, and a site on the ilium 3 cm above the acetabular roof were selected as fluoroscopic imaging centers. For the proximal femur, the base of the femoral neck, the femoral shaft at the level of the lesser trochanter, and the inferior border of the great trochanter were selected as fluoroscopic imaging centers.

Results: Target registration error (TRE) differed significantly among the selected fluoroscopic imaging centers. The best mean TRE for the pelvis was 0.8 mm (range: 0.2 to 1.6 mm) with the imaging center on the ilium (3 cm above the acetabular roof). The best mean TRE for the proximal femur was 1.1 mm (range: 0.2 to 2.0 mm) with the imaging center on the femoral shaft at the lesser trochanter level.

Conclusion: Fluoroscopic imaging center location had a significant effect on the accuracy of the CT-based 3D fluoroscopy matching navigation system in the pelvic and femoral regions. The proper fluoroscopic imaging centers for CT-3D fluoroscopic matching were, for the pelvis, a site on the ilium 3 cm above the acetabular roof, and for the proximal femur, the femoral shaft at the level of the lesser trochanter.