University of Twente Student Theses


CT-based migration analysis of tibial components in total knee arthroplasty

Laat, N.N. de (2022) CT-based migration analysis of tibial components in total knee arthroplasty.

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Abstract:Introduction: Early implant migration is considered a predictive factor of aseptic loosening in total knee arthroplasty (TKA). Relatively large initial migration, and/or continuous migration, is indicative for an increased risk of aseptic loosening. The gold standard to measure migration is currently roentgen stereophotogrammetric analysis (RSA). However, RSA is complex in common practice due to the use of a calibration cage, trained radiology personnel and insertion of bone markers. To overcome these disadvantages, a computed tomography (CT) based method has been proposed as alternative. This CT-based migration analysis (CTBMA) measures the displacement of orthopedic implants relative to the host bone over time in CT images. Objective: Comparison of migration measurement in tibial components in TKA between CTBMA and model-based RSA. Method: In a prospective study, tibial component migration was measured between one year (YR1) and five years (YR5) postoperative after primary TKA with CTBMA and model-based RSA. For CTBMA, the tibia (bone) and tibial component were segmented in the CT image of YR1. The underlying voxel intensities of these volumes were matched on the CT image of YR5 using image registration. The resulting rigid transformation of both volumes were used to calculate the relative displacement of the tibial component to the tibia. This resulted in translations along and rotation around X-axis (transverse), Y-axis (longitudinal) and Z-axis (sagittal). Total translations (TT) and total rotations (TR) were calculated with root sum square. Bland-Altman plots were constructed to determine the mean difference and limits of agreement (mean ± 1.96 SD) between CTBMA and RSA. Results: Seventeen patients were included for the comparison of CTBMA and RSA. The mean difference was -0.07 mm [-0.46 mm to 0.33 mm] and -0.12° [-0.88° to 0.64°] for TT and TR, respectively. The limits of agreement did not exceed ± 0.5 mm for translations. For rotations the limits of agreement were: X-axis [-0.98° to 0.94°], Y-axis [-0.89° to 0.85°] and Z-axis [-0.67° to 0.51°]. Discussion: We showed that CTBMA is feasible for tibial components in TKA in clinical practice and that the method agrees sufficiently with RSA. Similarly to RSA, it is important to determine the clinical precision of CTBMA, which was not done in the current study, but is advised to do in future research. Overall, CTBMA seems a promising marker-free alternative to RSA for evaluation of tibial component migration in TKA in hospitals with a similar CT scanner.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:50 technical science in general
Programme:Technical Medicine MSc (60033)
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