Institute of Sensor and Actuator Technology (ISAT), Coburg University of Applied Sciences and Arts, Am Hofbräuhaus 1b, 96450 Coburg, Germany.
Department of Trauma Surgery and Orthopedics, REGIOMED Clinical Center Coburg, Ketschendorfer Str. 33, 96450 Coburg, Germany.
Sensors (Basel). 2023 Jun 26;23(13):5942. doi: 10.3390/s23135942.
The loosening of an artificial joint is a frequent and critical complication in orthopedics and trauma surgery. Due to a lack of accuracy, conventional diagnostic methods such as projection radiography cannot reliably diagnose loosening in its early stages or detect whether it is associated with the formation of a biofilm at the bone-implant interface. In this work, we present a non-invasive ultrasound-based interferometric measurement procedure for quantifying the thickness of the layer between bone and prosthesis as a correlate to loosening. In principle, it also allows for the material characterization of the interface. A well-known analytical model for the superposition of sound waves reflected in a three-layer system was combined with a new method in data processing to be suitable for medical application at the bone-implant interface. By non-linear fitting of the theoretical prediction of the model to the actual shape of the reflected sound waves in the frequency domain, the thickness of the interlayer can be determined and predictions about its physical properties are possible. With respect to determining the layer's thickness, the presented approach was successfully applied to idealized test systems and a bone-implant system in the range of approx. 200 µm to 2 mm. After further optimization and adaptation, as well as further experimental tests, the procedure offers great potential to significantly improve the diagnosis of prosthesis loosening at an early stage and may also be applicable to detecting the formation of a biofilm.
人工关节松动是矫形和创伤外科中一种常见且严重的并发症。由于缺乏准确性，传统的诊断方法，如投影放射照相术，无法可靠地在早期诊断松动，也无法检测松动是否与骨-植入物界面处生物膜的形成有关。在这项工作中，我们提出了一种基于超声的非侵入性干涉测量程序，用于定量测量骨与假体之间的层厚，作为松动的相关指标。原则上，它还允许对界面的材料特性进行表征。将一个三层系统中反射声波的叠加的已知分析模型与一种新的数据处理方法相结合，使其适用于骨-植入物界面的医学应用。通过对模型的理论预测与实际反射声波形状在频域中的非线性拟合，可以确定层间的厚度，并对其物理性质进行预测。就确定层的厚度而言，所提出的方法已成功应用于理想化的测试系统和骨-植入物系统，范围约为 200 µm 至 2 mm。经过进一步的优化和适应，以及进一步的实验测试，该程序具有很大的潜力，可以显著提高早期假体松动的诊断水平，也可能适用于检测生物膜的形成。
