Ultrasound-Based Interferometric Hip Implant Monitoring

Abstract

Early detection of aseptic or septic loosening of hip endoprostheses is clinically crucial but still relies primarily on projection radiography, which lacks sensitivity for sub-millimetre interlayers at the bone–implant interface. Recent work by Lützelberger et al. demonstrated that ultrasound interferometry enables quantification of the width of this interface by analysing frequency-domain interference patterns of reflections from the soft-tissue gap. However, several open theoretical questions remained, particularly regarding the fundamental detection limits for small gap widths and the optimal choice of excitation frequency. This work provides a mathematical analysis of (i) the minimal resolvable gap width based on the Gabor limit, bandwidth constraints, and the signal-to-noise ratio (SNR) and (ii) the optimal operating frequency considering attenuation in soft tissue and the limited thickness of the cortical bone layer. The results show that an excitation frequency around 3 MHz represents an optimum here. Furthermore, closed-form expressions for the minimum detectable width are derived, predicting detection thresholds in the range of 156–212 µm for different SNR conditions – consistent with previously reported experimental results. These findings provide theoretical justification for system design choices in interferometric ultrasound for implant-integration monitoring.

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Titel Ultrasound-Based Interferometric Hip Implant Monitoring
Medien Proceedings, iCCC2026 - iCampus Cottbus Conference 2026, Cottbus, 2026
Herausgeber AMA Service GmbH
ISBN 978-3-910600-10-2
Verfasser M.Eng. Jan Lützelberger, Prof. Dr. Klaus Stefan Drese
Seiten 115-118
Veröffentlichungsdatum 07.05.2026
Projekttitel UltraHip
Zitation Lützelberger, Jan; Drese, Klaus Stefan (2026): Ultrasound-Based Interferometric Hip Implant Monitoring. Proceedings, iCCC2026 - iCampus Cottbus Conference 2026, Cottbus, 2026, 115-118. DOI: 10.5162/iCCC2026/7.3