High precision and accuracy of model‐based RSA for analysis of wrist arthroplasty

Abstract

Radiostereometric analysis (RSA) is a method for measuring micromotion in joint arthroplasties. RSA has never been used in total wrist arthroplasties. We evaluated: (i) the precision of model-based RSA in total wrist arthroplasties measured in a phantom model and in patients; (ii) the number of bone markers necessary to ensure the precision; and (iii) the accuracy of model-based RSA in a phantom model. Reverse engineered models of radial and carpal/metacarpal components of two wrist arthroplasties (ReMotion® and Motec®) were obtained by laser scanning. Precision and accuracy of each arthroplasty were analyzed with regards to translation and rotation along the three coordinate axes. Precision was analyzed in 10 phantom and 30 clinical double examinations for each arthroplasty, and was expressed by a repeatability coefficient. The precision of different numbers and configurations of bone markers in the phantom model were compared. Accuracy was tested in a phantom model where the implants were attached to a micrometer, and was defined as the mean difference between measured and true migration. In the phantom model the precision for translations ranged from 0.03 to 0.14 mm and for rotations from 0.18 to 1.52°. In patients the precision for translations ranged from 0.06 to 0.18 mm, and for rotations from 0.32 to 2.18°. Less than four bone markers resulted in inferior precision. Accuracy ranged from -0.06 to 0.04 mm, and from -0.38 to -0.01°. Y-rotations could not be obtained from the Motec® due to rotational symmetry about the longitudinal axis. We conclude that model-based RSA in total wrist arthroplasties is precise, accurate, and feasible to use for clinical evaluation of micromotion in wrist arthroplasties. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999: 1-12, 2018.

A randomized controlled trial comparing two modern total wrist arthroplasties

“…Perioperatively, six to ten 1 mm tantalum beads were implanted in the radius and capitate (ReMotion) and the third metacarpal (Motec) using a hand-operated spring-loaded piston (RSA Biomedical, Sweden). RSA radiographs were obtained as described by Holm-Glad et al 17 two to four days, three, six, 12, and 24 months postoperatively, or prior to revision of loose implants. The first examination served as reference.…”

“…Precision for translations in TWA is equal to total hip arthroplasty (THA) and total knee arthroplasty (TKA), whereas precision for rotations is equal or less. 17…”

Accuracy of radiographic measurements of fracture-induced deformity in the distal radius

“…Low condition numbers indicate well-dispersed markers where close and/or co-aligned markers increase the condition number. 18 Condition numbers <300 is recommended. 19 …”

A Perspective on Biotribology in Arthroplasty: From In Vitro toward the Accurate In Silico Wear Prediction

“…MRI calculation methods can vary by analyzing the images at different slice intervals (or interval gaps) along the length of the body [15]. The RSA is used in the orthopedic field to measure the translations/migration of joint replacement components with respect to the host bone in vivo [16][17][18]. This kind of application is able to detect early stages of particle disease before osteolysis is apparent on radiographs.…”

“…Obviously, the precision and accuracy of the method should be determined from time to time when a new anatomical area or a new prosthetic design is considered. In particular, precision is equal to repeatability and defined as the agreement between two test results under the same conditions; the accuracy, instead, is the "trueness" of a measurement, and it is defined as the closeness of agreement between a test result and a known value [17][18][19]. In particular, Seehaus and colleagues [20] suggest that RSA is an alternative method for in vivo measurement of implant migration; they found an accuracy that ranged from −0.048 to 0.037 mm, and −0.057 • to 0.078 • or translation and rotation respectively.…”