Abstract
The purpose of this study was to determine contact patterns in cementless acetabular cups using a novel computed tomography (CT) scan analysis technique. Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive one of three cup designs. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone pros-thesis contact.
The purpose of this study was to determine contact patterns in cementless acetabular cups using computed tomography (CT) scan analysis.
Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive a hemispherical cup, a dual geometry cup, or a spiked cup. After radiographic templating, an experienced orthopaedic team prepared the specimens and implanted the acetabular cups. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. Contact was defined as a bone-prosthesis distance of 0.5 mm or less.
The mean amount of cup contact was 40.4% (SD=8.2%) in the hemisphere group, 24.7% (SD=2.3%) in the dual geometry group, and 29.7% (SD=9.5%) in the spiked group. Colour mapping of the bone-prosthesis gap was used to identify contact/non-contact regions along the acetabular contour for all cup designs.
Preliminary work with this CT analysis technique demonstrates differences in the amount and distribution of contact in the acetabular cup designs. Future work will involve development of an imaging phantom to clarify error, use of the technique with different cup designs and reaming techniques, and comparison of this technique with conventional CT scan techniques.
This study outlines a novel CT analysis technique for quantitatively determining bone-prosthesis contact for cementless acetabular cups.
The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone prosthesis contact.
Funding: Smith and Nephew
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
