Shaver S M, Brown T D, Hillis S L, Callaghan J J
The University of Iowa, Iowa City 52242-1008, USA.
J Bone Joint Surg Am. 1997 May;79(5):690-700. doi: 10.2106/00004623-199705000-00008.
A novel digital edge-detection computer technique was developed to measure polyethylene wear after total hip arthroplasty. The new method objectively infers the margins of the component by evaluating gradients of gray-scale intensity on digitized images of the radiographs. Compared with previous methods for measurement of wear, digital edge detection substantially reduces observer subjectivity. The technique was validated directly by measuring wear artificially produced by spherical-front milling of polyethylene liners in a benchtop series. Under such conditions, digital edge detection proved 6.4 times more accurate and 7.1 times more reproducible than manual measurement with conventional circular templates. In addition, clinical application of the new digital imaging technique was illustrated in a series of forty-three patients in whom a metal-backed acetabular cup had been inserted with cement. A random-coefficients prediction algorithm was invoked to estimate long-term wear (mean late rate of wear for the cohort, 0.087 millimeter per year at a mean of 118 months after the operation) on the basis of measurements of short-term wear (mean early rate of wear for the cohort, 0.154 millimeter per year at a mean of twenty-four months).
开发了一种新型数字边缘检测计算机技术，用于测量全髋关节置换术后聚乙烯磨损情况。该新方法通过评估X线片数字化图像上的灰度强度梯度，客观推断假体组件的边缘。与先前的磨损测量方法相比，数字边缘检测大大降低了观察者的主观性。通过在台式系列中测量聚乙烯内衬球形前铣削人工产生的磨损，直接验证了该技术。在这种情况下，数字边缘检测的准确性比使用传统圆形模板的手动测量高6.4倍，可重复性高7.1倍。此外，在一系列43例使用骨水泥植入金属背衬髋臼杯的患者中展示了这种新型数字成像技术的临床应用。调用随机系数预测算法，根据短期磨损测量值（该队列的平均早期磨损率为每年0.154毫米，平均在术后24个月）来估计长期磨损（该队列的平均晚期磨损率为每年0.087毫米，平均在术后118个月）。
