Guidelines for standardization of radiostereometry (RSA) of implants

TLDR

Standardization of radiostereometric (RSA) investigations is needed to enable comparison of outcomes across research groups. The paper seeks to standardize RSA validation by developing protocols for accuracy and precision assessment and providing a checklist for standardized output, forming the basis of a detailed ISO‑ and European‑standard protocol. Six research centers agreed on RSA terminology, description, radiographic setup, and techniques, and addressed practical issues such as joint loading, follow‑up intervals, radiation dose, and patient exclusion, culminating in a standardized checklist. Consensus established minimum requirements for marker stability, coordinate systems, and prosthetic micromotion description, added data‑interpretation notes, and proposed a protocol that will facilitate RSA inclusion in implant testing and reduce the risk of widespread implantation of inferior prostheses.

Abstract

There is a need for standardization of radiostereometric (RSA) investigations to facilitate comparison of outcome reported from different research groups. In this document, 6 research centers have agreed upon standards for terminology, description and use of RSA arrangement including radiographic set-up and techniques. Consensus regarding minimum requirements for marker stability and scatter, choice of coordinate systems, and preferred way of describing prosthetic micromotion is of special interest. Some notes on data interpretation are also presented. Validation of RSA should be standardized by preparation of protocols for assessment of accuracy and precision. Practical issues related to loading of the joint by weight bearing or other conditions, follow-up intervals, length of follow-up, radiation dose, and the exclusion of patients due to technical errors are considered. Finally, we present a checklist of standardized output that should be included in any clinical RSA paper.This document will form the basis of a detailed standardization protocol under supervision of ISO and the European Standards Working Group on Joint Replacement Implants (CEN/TC 285/WG4). This protocol will facilitate inclusion of RSA in a standard protocol for implant testing before it is released for general use. Such a protocol—also including other recognized clinical outcome parameters—will reduce the risk of implanting potentially inferior prostheses on a large scale.