在手术后前两年里,骨科植入物相对于骨组织的累积微动情况是可以测量的,测量结果可以预测植入物的机械松动。用于三维微动测量的最精确的X线成像方法是X线立体摄影测量分析法(RSA)。已证实的RSA方法的精确度为在移动方面是在0.05mm和0.5mm之间,在转动方面是在0.15度和1.15度之间。RSA方法用来研究植入方法的改变、覆盖物的增加或新型骨水泥等对假体稳固性的影响。RSA方法的优点是一般采用较少病人数量(25位病人)和较短时间的临床研究(2年)就足以预测很长时间内的植入物机械松动情况。这就促使RSA方法成为假体设计和开发研究中的重要检测工具,从而避免使大量病患处于新方法的潜在危险之中。在本文中,作者解释了RSA方法的基本原理,并列举了RSA的临床研究实例以阐释其临床应用。

Mechanical loosening of orthopaedic implants can be predicted by measuring the progressive micromotion of the implant with respect to the bone in the first two years after surgery.The most accurate Roentgen technique for three-dimensional assessment of micromotion is Roentgen Stereophotogrammetric Analysis(RSA).The reported accuracy of RSA ranges between 0.05 and 0.5 mm for translations and between 0.15 and 1.15 deg for rotations.RSA is used to study the effect on prosthetic fixation due to changes in implant design,addition of coatings,or new bone cements.The advantages of RSA are that small patient groups(i.e.25 patients) and short-term(i.e.2 years) clinical studies are in general sufficient to predict the likelihood of long-term(i.e.10 years) mechanical loosening of the prosthesis.This makes RSA an important measurement tool to study new developments in prosthetic design in order to prevent large patient groups from being exposed to potentially inferior designs.In this paper,the basics of the RSA technique will be explained,and some examples of clinical RSA studies will be presented to illustrate the clinical relevance of RSA.