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The position and orientation of total knee replacement components : a comparison of conventional radiographs, transverse 2D-CT slices and 3D-CT reconstruction
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
ID
1193124
Author(s)
Hirschmann, M. T.; Konala, P.; Amsler, F.; Iranpour, F.; Friederich, N. F.; Cobb, J. P.
The position and orientation of total knee replacement components : a comparison of conventional radiographs, transverse 2D-CT slices and 3D-CT reconstruction
Journal
The Journal of bone and joint surgery. A, American volume
Volume
93B
Number
5
Pages / Article-Number
629-633
Abstract
We studied the intra- and interobserver reliability of measurements of the position of the components after total knee replacement (TKR) using a combination of radiographs and axial two-dimensional (2D) and three-dimensional (3D) reconstructed CT images to identify which method is best for this purpose. A total of 30 knees after primary TKR were assessed by two independent observers (an orthopaedic surgeon and a radiologist) using radiographs and CT scans. Plain radiographs were highly reliable at measuring the tibial slope, but showed wide variability for all other measurements; 2D-CT also showed wide variability. 3D-CT was highly reliable, even when measuring rotation of the femoral components, and significantly better than 2D-CT. Interobserver variability in the measurements on radiographs were good (intraclass correlation coefficient (ICC) 0.65 to 0.82), but rotational measurements on 2D-CT were poor (ICC 0.29). On 3D-CT they were near perfect (ICC 0.89 to 0.99), and significantly more reliable than 2D-CT (p > 0.001). 3D-reconstructed images are sufficiently reliable to enable reporting of the position and orientation of the components. Rotational measurements in particular should be performed on 3D-reconstructed CT images. When faced with a poorly functioning TKR with concerns over component positioning, we recommend 3D-CT as the investigation of choice.
