Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9353924 | Journal of Orthopaedic Research | 2005 | 7 Pages |
Abstract
We developed, validated and assessed inter- and intraobserver reliability of a CT-scan based measurement tool to evaluate morphological characteristics of the bone-cement-stem complex of hip implants in cadaver femurs. Two different models were investigated: the stem-cavity model using a double tapered polished femoral-stem that is removed after cement curing and the plastic-replica model using a stereolithographic stem replica that is left in place during CT-scanning. Software was developed to segment and analyze connective CT-images and identify the contours of bone, cement, and stem based on their respective gray values. Volume parameters (whole specimen, cement, stem, air contents of bone and cement), concentricity parameters (distances between centroids of stem and cement, cement and bone, stem and bone), contact surfaces (bone/air and cement/bone) and bone cement mantle thickness parameters were calculated. A three-dimensional protocol was developed to evaluate the minimal mantle thickness out of the CT-plane. The average accuracy for surfaces within CT-images was 7.47Â mm2 (1.80%), for bone and cement mantle thickness it was 0.51Â mm (9.39%), for distances between centroids it was 0.38Â mm (18.5%) and contours: 0.27Â mm (2.57%). The intra- and interobserver reliability of air content in bone and cement was sub-optimal (intraclass-correlation coefficient (ICC) as low as 0.54 with an average ICC of 0.85). All other variables were reliable (ICCÂ >Â 0.81, average ICC: 0.96). This in vitro technique can assess characteristics of cement mantles produced by different cementing techniques, stem types or centralizers.
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Authors
Thierry Scheerlinck, Johan de Mey, Rudi Deklerck,