Full-field measurement of micromotion around a cementless femoral stem using micro-CT imaging and radiopaque markers

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• 作者：V. Malfroy Camine^a ; H.A. Rü ; diger^b ; ^c ; D.P. Pioletti^a ; A. Terrier^a ; ^{alexandre.terrier@epfl.ch}
• 关键词：Primary stability ; Micromotion ; Femoral stem ; Micro-CT ; Total hip replacement
• 刊名：Journal of Biomechanics
• 出版年：2016
• 出版时间：8 December 2016
• 年：2016
• 卷：49
• 期：16
• 页码：4002-4008
• 全文大小：1377 K
• 卷排序：49

文摘

A good primary stability of cementless femoral stems is essential for the long-term success of total hip arthroplasty. Experimental measurement of implant micromotion with linear variable differential transformers is commonly used to assess implant primary stability in pre-clinical testing. But these measurements are often limited to a few distinct points at the interface. New techniques based on micro-computed tomography (micro-CT) have recently been introduced, such as Digital Volume Correlation (DVC) or markers-based approaches. DVC is however limited to measurement around non-metallic implants due to metal-induced imaging artifacts, and markers-based techniques are confined to a small portion of the implant. In this paper, we present a technique based on micro-CT imaging and radiopaque markers to provide the first full-field micromotion measurement at the entire bone–implant interface of a cementless femoral stem implanted in a cadaveric femur. Micromotion was measured during compression and torsion. Over 300 simultaneous measurement points were obtained. Micromotion amplitude ranged from 0 to 24 µm in compression and from 0 to 49 µm in torsion. Peak micromotion was distal in compression and proximal in torsion. The technique bias was 5.1 µm and its repeatability standard deviation was 4 µm. The method was thus highly reliable and compared well with results obtained with linear variable differential transformers (LVDTs) reported in the literature. These results indicate that this micro-CT based technique is perfectly relevant to observe local variations in primary stability around metallic implants. Possible applications include pre-clinical testing of implants and validation of patient-specific models for pre-operative planning.