Ilchmann T
Department of Orthopedics, Lund University Hospital, Sweden.
Acta Orthop Scand Suppl. 1997 Oct;276:1-26. doi: 10.1080/17453674.1997.11744768.
Methods are needed for accurate measurement of acetabular cup migration and wear after hip replacement. The EBRA (Ein Bild Röntgen Analyse) method was recently introduced as computerized method for radiographic assessment of acetabular cup migration. In this study, various standard methods for measuring migration were evaluated and compared to radiostereometry (RSA), which has proved to be highly accurate. A subroutine for wear measurement was developed and added to the EBRA method. Of the standard methods, Nunn's method was the best for migration measurement and Livermore's the best for wear measurement. Measurements with EBRA were better than the standard methods. Pelvic tilt seemed to be the main source of error in measurements. The effect of pelvic tilt was evaluated experimentally. EBRA detected and excluded tilted radiographs, the errors of measurement being smaller with EBRA than with standard methods. The precision of the input procedure, repeated radiographic examination, the intra- and interobserver errors were assessed. Apart from the digital input of the data, EBRA was better than the standard methods. Normal values concerning acetabular cup migration and wear should be obtained from long-term surviving hip replacements, without radiographic signs of loosening. No method of measurement detected evidence of changes in the wear-rate and in migration over time. EBRA showed cold-flow in some cups, but did not provide additional information in the long-term. Nunn's method for migration measurements and Livermore's method for wear are recommended in clinical practice. EBRA is more accurate and should be used for studies of new implant designs that have passed the preclinical and, preferably, radiostereometric analysis. RSA is unsurpassed and is recommended for early clinical follow-up in a limited number of patients.
需要有方法来准确测量髋关节置换术后髋臼杯的移位和磨损情况。EBRA（单幅X线分析）方法最近作为一种用于髋臼杯移位的放射学评估的计算机化方法被引入。在本研究中，对各种测量移位的标准方法进行了评估，并与已被证明高度准确的放射立体测量法（RSA）进行了比较。开发了一个磨损测量子程序并添加到EBRA方法中。在标准方法中，Nunn法在移位测量方面最佳，Livermore法在磨损测量方面最佳。EBRA测量比标准方法更好。骨盆倾斜似乎是测量误差的主要来源。通过实验评估了骨盆倾斜的影响。EBRA能检测并排除倾斜的X线片，EBRA测量的误差比标准方法小。评估了输入程序的精度、重复放射学检查、观察者内和观察者间误差。除了数据的数字输入外，EBRA比标准方法更好。髋臼杯移位和磨损的正常值应从长期存活且无松动放射学迹象的髋关节置换术中获取。没有测量方法能检测到磨损率和移位随时间变化的证据。EBRA在一些髋臼杯中显示出冷流，但从长期来看并未提供额外信息。临床实践中推荐使用Nunn法进行移位测量，Livermore法进行磨损测量。EBRA更准确，应在新植入物设计通过临床前和（最好）放射立体测量分析后用于相关研究。RSA无与伦比，推荐用于少数患者的早期临床随访。
