Radiostereometric analysis (RSA) RSA, first developed in Lund, Sweden, is a radiographic technique for accurately assessing implant position relative to host bone. RSA is the gold standard for measuring implant stability in the short-term and predicting implant survivorship in the long-term. It has been implemented for several decades and its safety is well documented. RSA is 10 times more accurate than conventional radiography in analyzing implant migration patterns. Patterns of micromigration exhibited by various prostheses and fixation techniques within the first post-operative year has been shown to predict long-term component fixation to bone.