The History and Future of Radiostereometric Analysis

Abstract

Roentgen stereophotogrammetry allows one to localize the position of an object in space using roentgen rays. For orthopaedic purposes it was developed 35 years ago by Göran Selvik, and since that time many investigators have refined the radiostereometric calculations and evaluative software. Many uses and mathematical algorithms have been developed, and advancements in computer programs and digital radiography continue to expand its capabilities. Despite these advances, improvements in the technical accuracy and type of kinematic analyses possible have been relatively modest. However, radiostereometric analysis is now easier and less time consuming to use, with a resolution in clinical practice almost equal to what could only previously be obtained under ideal laboratory conditions. The ability to measure skeletal and implant movements with high resolution in vivo images was an important progressive step for the orthopaedic community. Radiostereometric analysis has helped develop new fields in clinical orthopaedic research and continues to improve advancements in orthopaedic health care.

Accuracy of Model-based RSA Contour Reduction in a Typical Clinical Application

“…Marker-based RSA is considered the gold standard for measurement of implant migration, and it has been used as a standard of comparison for other radiographic methods, such as the Sutherland, Wetherell, and Sulzer methods or EBRA (Ein-Bild-Röntgen-Analyse, single-image roentgen analysis) [2,6]. Possible disadvantages of the marker-based RSA method, such as prosthesis marker occlusion or increasing cost of additional implant marking, could be compensated by the new model-based method [10,14,26]. The model-based method we used was validated in another clinical investigation of TKA implant migration [9].…”

“…Pose estimation techniques are the digital equivalent of casting shadows, by which the location of objects is determined by the projection of a silhouette to the image plane or planes. The placement of tantalum implant markers required with marker-based techniques therefore is no longer necessary; thus, the associated risks (initiation of cement cracking), technical problems (implant marker obfuscation), and cost (recertification cost) are eliminated [10,14]. The MBRSA method can be distinguished from other shape-based methods [4,8] in that it does not require specific implant geometries or shapes such as spherical femoral head and/or acetabular components.…”

Differentially Loaded Radiostereometric Analysis to Monitor Fracture Stiffness: A Feasibility Study

“…It has been used predominantly in studies monitoring prosthesis migration and is considered the gold standard method [21,22,31,36,40,42,43,46]. The method requires small tantalum markers to be inserted intraoperatively and two simultaneous radiographs taken over a calibration cage at selected times postoperatively.…”

“…Radiostereometric analysis (RSA) is considered the most accurate radiographic method for measuring skeletal or implant movements in vivo [21]. It has been used predominantly in studies monitoring prosthesis migration and is considered the gold standard method [21,22,31,36,40,42,43,46].…”

Does Cup-cage Reconstruction With Oversized Cups Provide Initial Stability in THA for Osteoporotic Acetabular Fractures?

“…However, plain radiographs cannot detect the suggested acceptable thresholds of 1.76 mm proximal migration and 2.53°sagittal rotation that may predict late aseptic loosening [19]. By contrast, radiostereometric analysis (RSA) is the most sensitive in vivo technique to assess prosthesis migration [9] and was the technique used to establish these thresholds [19]. Therefore, the primary aim of this study was to determine the early migration of the acetabular component in THA performed for acute osteoporotic acetabular fractures in our institution using RSA.…”