Radiostereometric analysis using clinical radiographic views: Validation measuring total hip replacement wear

Abstract

Radiostereometric analysis (RSA) is a stereo X-ray technique used in clinical research studies to evaluate micro-motion and wear of orthopaedic implants within bone. While highly accurate and precise, its adoption has been limited due to technical requirements such as the need for implanted marker beads and radiograph view angles determined by a calibration cage. We propose a new technique that separates the calibration procedure from the patient examination, enabling clinical radiograph views to be used for RSA measurements. The concept of a reference plate was adapted to establish the link between calibration procedure and patient examination procedure for cassette radiography, which may not be necessary for digital radiography. A hip wear phantom was used to validate this technique by comparing the error and repeatability of the novel procedure with that of conventional RSA. Femoral head penetration was measured versus the acetabular cup (head/cup) and marker beads in the acetabular liner (head/liner). Conventional RSA had lower inferior-superior average error (p ¼ 0.03 for head/cup) while the modified RSA had lower anterior-posterior average error (p ¼ 0.01). Average error was greater but not significantly so for the medial-lateral (p ¼ 0.06) and 3D (p ¼ 0.97) measurements. The head/liner method had lower average errors (p < 0.0001) for both procedures, but did not affect repeatability, which was similar between techniques. The novel procedure's average error and repeatability was therefore, similar to conventional RSA. This new technique could be applied to any joint with two clinical radiograph view angles pending further validation in subjects. ß

Accuracy of methods to measure femoral head penetration within metal-backed acetabular components

“…The model-based RSA software had higher errors in the anterior axis and resultant 3D measurements. 22 Previously, the accuracy of the RSA method was improved when more markers were used to represent the acetabular component 30,36 but this was not the case in our study. Only one study has compared the accuracy of different acetabular reference segments with and without ellipse algorithms 27 and our study confirmed that there was no significant difference in the accuracy using different representations of the acetabular component (Table 4).…”

Radiostereometric analysis using clinical radiographic views: Validation with model-based radiostereometric analysis for the knee

“…In our previous study under a CR environment, a numerical registration approach was presented. 17 It first measured the calibration radiographs and phantom images individually, then registered both measurements together numerically. It should be emphasized that these different approaches provide equivalent outcomes in RSA.…”

Investigation of imaging magnification in radiostereometric analysis

“…It not only reduces the cost for RSA studies but also provides the opportunity to apply a novel RSA method with clinical radiographic views. 12 Furthermore, it makes RSA more accessible to clinics. This novel RSA method separates the calibration radiographic procedure from the patient radiographic procedure.…”

“…11 The usage of CR in RSA largely reduces the measurement time, but still retains the original format of the RSA method, which was designed for small patient groups and used special X-ray viewing angles that are different from the clinical standards. 12 A new and emerging form of digital projection radiography is flat panel digital radiography (DR). DR directly converts X-ray energy from a thin film transistor (TFT) medium into electrical signals to generate digital images.…”