Validation of a three-dimensional low dose CT method for assessing migration and loosening in orthopaedic implants

Abstract

Aseptic loosening is the most common complication following arthroplasty. Early migration and the development of radiolucent lines are believed to be correlated to aseptic loosening. As of late, computed tomography (CT) is considered an alternative to radiostereometry (RSA) and standard X-rays for assessing these two occurrences. The aim of this thesis is to investigate whether a commercially available CT micromotion analysis (CTMA) software can be used to follow early migration and radiolucent lines in orthopaedic implants. Cadaveric and clinical studies were performed to estimate the precision, accuracy, and effective dose of CTMA for different orthopaedic implant components using different CT scanners and CT protocols. Precision and effective dose of CTMA were compared to those of radiostereometry. Also, a clinical proof-of-concept study was performed to investigate if CTMA could measure early migration and development of radiolucent lines over time. The accuracy of CTMA with and without the use of beads was 0.07–0.23 mm and 0.22–0.71°. CTMA with and without the use of beads in the bone had a precision of 0.07–0.31 mm and 0.20–0.54°. CTMA precision did not vary extensively despite the variety of implant types, CT image acquisition equipment, and protocols employed. CTMA achieved a slightly better precision in rotation and a comparable precision in translation to RSA at a slightly higher effective dose. The development of radiolucent lines could be seen in CTMA and followed over time for glenoid components. In conclusion, CTMA is a tool that could be used to follow early migration and radiolucent lines in orthopaedic implants.