What is RSA?

“Since its introduction in 1974 (2686344), roentgen stereophotogrammetric analysis (RSA) has been widely used to assess migration and micromotion of orthopaedic implants. It is a highly accurate method of quantifying three-dimensional motion between an implant and the host bone.

Several studies have found implant migration to be predictive of long-term implant survival and, for most devices, measurement over 2 years might therefore provide a surrogate outcome measure with relatively low numbers of subjects, e.g. from 15 to 25 patients in each group in randomized studies (1544960), (7983118), (7744919). A smaller number of subjects can be used in these studies as a consequence of the high accuracy of the measurement technique. Because of this, RSA is an important technique in early clinical trials for screening new joint replacement prostheses. “