Department of Clinical Sciences, Biomaterial- and Biomechanical Laboratory, Lund University, Sweden.
Acta Orthop. 2011 Feb;82(1):35-41. doi: 10.3109/17453674.2011.552777. Epub 2011 Feb 1.
We evaluated the accuracy and repeatability of a 3D method for polyethylene acetabular cup wear measurements using computed tomography (CT). We propose that the method be used for clinical in vivo assessment of wear in acetabular cups.
Ultra-high molecular weight polyethylene cups with a titanium mesh molded on the outside were subjected to wear using a hip simulator. Before and after wear, they were (1) imaged with a CT scanner using a phantom model device, (2) measured using a coordinate measurement machine (CMM), and (3) weighed. CMM was used as the reference method for measurement of femoral head penetration into the cup and for comparison with CT, and gravimetric measurements were used as a reference for both CT and CMM. Femoral head penetration and wear vector angle were studied. The head diameters were also measured with both CMM and CT. The repeatability of the method proposed was evaluated with two repeated measurements using different positions of the phantom in the CT scanner.
The accuracy of the 3D CT method for evaluation of linear wear was 0.51 mm and the repeatability was 0.39 mm. Repeatability for wear vector angle was 17°.
This study of metal-meshed hip-simulated acetabular cups shows that CT has the capacity for reliable measurement of linear wear of acetabular cups at a clinically relevant level of accuracy.
我们评估了使用计算机断层扫描（CT）进行聚乙烯髋臼杯磨损测量的三维方法的准确性和可重复性。我们建议该方法用于髋臼杯磨损的临床体内评估。
在髋关节模拟器上对带有钛网模制在外表面的超高分子量聚乙烯杯进行磨损。在磨损前后，（1）使用带有仿体模型设备的 CT 扫描仪对其进行成像，（2）使用坐标测量机（CMM）进行测量，以及（3）称重。CMM 被用作测量股骨头穿透杯的参考方法，并与 CT 进行比较，而重量测量被用作 CT 和 CMM 的参考。研究了股骨头穿透和磨损矢量角度。还使用 CMM 和 CT 测量了头直径。使用 CT 扫描仪中不同的仿体位置进行了两次重复测量，以评估该方法的可重复性。
用于评估线性磨损的三维 CT 方法的准确性为 0.51mm，可重复性为 0.39mm。磨损矢量角度的可重复性为 17°。
这项对金属网髋关节模拟髋臼杯的研究表明，CT 具有在临床相关的精度水平可靠测量髋臼杯线性磨损的能力。
