Collier Matthew B, Kraay Matthew J, Rimnac Clare M, Goldberg Victor M
Department of Mechanical and Aerospace Engineering, Orthopaedic Engineering Laboratories, Case Western Reserve University, 10900 Euclid Avenue, Glennan Building 620, Cleveland, OH 44106-7222, USA.
J Bone Joint Surg Am. 2003 Dec;85(12):2410-8. doi: 10.2106/00004623-200312000-00020.
Radiographic measurements of the wear of total hip arthroplasty implants are indirect measurements based on radiographic determinations of the location of the femoral head relative to the acetabular component. Using the simplest case of zero wear, we assessed the reproducibility and accuracy of two software applications designed to quantify wear from clinical radiographs.
After a cobalt-chromium head was glued into the polyethylene liner of a titanium shell, one cross-table lateral radiograph and three anteroposterior pelvic radiographs were made for twelve permutations of acetabular component angulation. The three anteroposterior radiographs differed only with regard to the cephalocaudal positioning of the prosthesis relative to the x-ray tube. To assess method reproducibility, each anteroposterior radiograph was assumed to be both the initial and the latest follow-up radiograph of a wear analysis. To assess method accuracy, each anteroposterior radiograph was paired in a wear analysis with each of the two anteroposterior radiographs made when the component was in the same angulation but at a different cephalocaudal position relative to the tube (one radiograph was the initial follow-up radiograph while the second was the latest follow-up radiograph). The analyses of reproducibility and accuracy were performed both with and without inclusion of the lateral radiograph made with the component in the same angulation.
Both methods fared well in the reproducibility analyses, with mean linear and volumetric wear values of 0.00 to 0.07 mm and 0 to 24 mm(3), respectively. In the accuracy analyses, the mean linear and volumetric wear values derived with the two methods were 0.26 to 0.40 mm and 78 to 126 mm(3), respectively.
Whereas the results of the reproducibility analyses showed that the methods were consistent in determining the relative positions of the head and shell from a given anteroposterior radiograph or pair of anteroposterior and lateral radiographs, the non-zero wear results obtained in the accuracy analyses proved that these positional determinations were often inaccurate. Thus, while contemporary software methods may yield reproducible results, their accuracy is limited by their inability to correctly determine the position of the head relative to the acetabular component.
全髋关节置换植入物磨损的影像学测量是基于股骨头相对于髋臼部件位置的影像学测定的间接测量方法。我们以最简单的零磨损情况为例,评估了两种用于从临床X线片量化磨损的软件应用程序的可重复性和准确性。
将一个钴铬合金股骨头粘入钛合金髋臼杯的聚乙烯内衬后,针对髋臼部件的12种角度排列拍摄了一张交叉台面侧位X线片和三张前后位骨盆X线片。三张前后位X线片仅在假体相对于X线球管的头足位定位方面有所不同。为了评估方法的可重复性,每张前后位X线片都被假定为磨损分析的初始和最新随访X线片。为了评估方法的准确性,在磨损分析中,将每张前后位X线片与当部件处于相同角度但相对于球管的头足位位置不同时拍摄的另外两张前后位X线片中的每一张进行配对(一张X线片是初始随访X线片,另一张是最新随访X线片)。在包含和不包含部件处于相同角度时拍摄的侧位X线片的情况下,均进行了可重复性和准确性分析。
两种方法在可重复性分析中表现良好,平均线性磨损值和体积磨损值分别为0.00至0.07毫米和0至24立方毫米。在准确性分析中,两种方法得出的平均线性磨损值和体积磨损值分别为0.26至0.40毫米和78至126立方毫米。
虽然可重复性分析的结果表明,这些方法在从给定的前后位X线片或一对前后位和侧位X线片中确定股骨头和髋臼杯的相对位置时是一致的,但准确性分析中获得的非零磨损结果证明,这些位置确定往往不准确。因此,虽然当代软件方法可能会产生可重复的结果,但其准确性受到其无法正确确定股骨头相对于髋臼部件位置的限制。