Department of Orthopaedic Surgery, Université Paris Descartes, Paris, France.
Acta Orthop. 2010 Oct;81(5):563-9. doi: 10.3109/17453674.2010.519163.
Current techniques for measuring in vivo polyethylene wear suffer from a range of problems, resulting in an unacceptable lack of repeatability and/or insufficient accuracy when they are used to measure the low wear rates associated with new, highly crosslinked polyethylene. We describe an improved CT method for measurement of 3D femoral head penetration in PE acetabular cups that has sufficient accuracy and repeatability to allow assessment of the wear potential of modern implants.
The accuracy and repeatability of the CT-scan method was determined by blindly repeating measurements on a precisely calibrated 28-mm prosthetic head and by comparing them with direct metrological measurements on 10 acetabular specimens with in vitro wear from machining, and on 8 explanted acetabular specimens with in vivo wear.
The intra- and interobserver errors in femoral head diameter were 0.036 mm (SD 0.044) and 0.050 mm (SD 0.022), respectively. CT estimated femoral head penetration in both all-poly and metal-backed acetabular components with accuracy ranging from 0.009 to 0.245 mm (mean 0.080; SD 0.067).
We found that the CT method is rapid, is accurate, and has repeatability and ease of availability. Using a slice thickness of 0.0625 mm, this method can detect wear—and also the threshold for the wear rate that causes osteolysis—much earlier than previous methods.
目前用于测量体内聚乙烯磨损的技术存在一系列问题，导致在测量与新的高度交联聚乙烯相关的低磨损率时，可重复性和/或准确性较差。我们描述了一种改进的 CT 方法，用于测量髋臼聚乙烯杯内的 3D 股骨头穿透，该方法具有足够的准确性和可重复性，可用于评估现代植入物的磨损潜力。
通过在经过精确校准的 28 毫米假体头部上进行盲目重复测量，并将其与 10 个髋臼样本的体外磨损进行直接计量测量以及 8 个具有体内磨损的髋臼样本进行比较，确定 CT 扫描方法的准确性和可重复性。
股骨头直径的观察者内和观察者间误差分别为 0.036 毫米（SD 0.044）和 0.050 毫米（SD 0.022）。CT 估计全聚乙烯和金属背衬髋臼组件的股骨头穿透量，准确性范围为 0.009 至 0.245 毫米（平均值为 0.080；SD 0.067）。
我们发现该方法快速、准确，具有可重复性和易于获取性。使用 0.0625 毫米的切片厚度，该方法可以比以前的方法更早地检测到磨损，以及导致骨溶解的磨损率阈值。
