Background: We investigated the reliability of measurement of the alignment and position of the prosthetic components after total hip arthroplasty (THA) using three-dimensional computed tomography (CT)-based postoperative evaluation software.
Methods: We evaluated the postoperative CT data from 20 hips in 20 patients, using postoperative evaluation software. The alignment and three-dimensional positioning of the cup and stem were assessed by eight orthopedic surgeons for repeatability (intraobserver reliability) and reproducibility (interobserver reliability) of postoperative evaluation software using intra-class correlation coefficients (ICC). The radiographic inclination (RI) and radiographic anteversion (RA) of the cup, and anteversion, varus-valgus angle and flexion-extension angles of the stem were measured for alignment. The implant positioning was measured along three axes, X-axis (transverse), Y-axis (sagittal), and Z-axis (longitudinal).
Results: The intra- and inter-observer ICC of alignment measurement were very good for both cup and stem (0.86–1.00). The intra-observer and inter-observer ICC of cup positioning were very good in X-axis and Y-axis (0.91–0.94) and good in Z-axis (0.68–0.80). The intra-observer and inter-observer ICC of implant positioning were very good for the stem (0.98–0.99) for all axes.
Conclusion: CT-based postoperative evaluation software was able to evaluate the position of total hip implants with high reproducibility.

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Posted 20 Jul, 2020
Posted 20 Jul, 2020
Background: We investigated the reliability of measurement of the alignment and position of the prosthetic components after total hip arthroplasty (THA) using three-dimensional computed tomography (CT)-based postoperative evaluation software.
Methods: We evaluated the postoperative CT data from 20 hips in 20 patients, using postoperative evaluation software. The alignment and three-dimensional positioning of the cup and stem were assessed by eight orthopedic surgeons for repeatability (intraobserver reliability) and reproducibility (interobserver reliability) of postoperative evaluation software using intra-class correlation coefficients (ICC). The radiographic inclination (RI) and radiographic anteversion (RA) of the cup, and anteversion, varus-valgus angle and flexion-extension angles of the stem were measured for alignment. The implant positioning was measured along three axes, X-axis (transverse), Y-axis (sagittal), and Z-axis (longitudinal).
Results: The intra- and inter-observer ICC of alignment measurement were very good for both cup and stem (0.86–1.00). The intra-observer and inter-observer ICC of cup positioning were very good in X-axis and Y-axis (0.91–0.94) and good in Z-axis (0.68–0.80). The intra-observer and inter-observer ICC of implant positioning were very good for the stem (0.98–0.99) for all axes.
Conclusion: CT-based postoperative evaluation software was able to evaluate the position of total hip implants with high reproducibility.

Figure 1

Figure 2

Figure 3

Figure 4
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