Computed tomographic analysis of bone support for three acetabular cup designs.

The initial stability and long-term survivorship of cementless acetabular components is partially dependent on bone-prosthesis contact patterns. This study addresses the question: What are the differences in contact patterns for hemispheric, dual geometry, and spiked designs? Quantitative and qualitative assessment of contact patterns was achieved using a novel, nondestructive computed tomography-based analysis. Eighteen cadaveric hemipelvis specimens were randomly assigned to receive one of three cup designs. The mean amount of cup contact was 48.6% in the hemisphere group, 31.9% in the dual geometry group, and 35.1 percent in the spiked group. The hemispheric design showed more contact and a more uniform contact pattern than the dual geometry design. The dual geometry design featured a tight fit at the rim of the implant. In the spiked group, the amount of bone-prosthesis contact was affected by the distance that the spikes advanced into the pelvic bone. This nondestructive imaging technique has potential future uses in in vitro and in vivo studies.