Computed tomography-based radiostereometric analysis in orthopedic research: practical guidelines

Abstract

Early implant migration is an indicator of the long-term survival/failure of implants. CT-based radio-stereometric analysis (CT-RSA) is a precise method for measuring and visualizing implant migration in vivo using image processing of CT scans. This makes the method widely applicable to orthopedic researcher.Since its development in the early 2000s, CT-RSA has benefited from breakthroughs in CT and computing technology. These advancements have allowed for the acquisition of images with higher resolution at a much lower radiation dose. As a result, the measurement precision of CT-RSA is now comparable to that of the current gold standard technology while still compatible with most ethical considerations regarding radiation exposure.In this review we present bests practices for the successful execution of CT-RSA research projects. These practices are based on experience from projects on the hip, knee, shoulder, lower back, cervical spine, foot, pelvis, and wrist.

Guideline for RSA and CT-RSA implant migration measurements: an update of standardizations and recommendations

“…CT-RSA brings both new possibilities and challenges to prostheses migration measurements. It differs from standard RSA with both strengths and weaknesses, which it is worthwhile to elucidate [35]. As the body of knowledge for CT-RSA is growing rapidly, this method will be addressed in this paper as well.…”

“…However, for reasons of increased demands on certification, implant manufacturers do not attach markers to the prostheses any longer. For model-based RSA, prosthesis markers are not necessary [26,56,57], and for CT-RSA, neither bone nor prosthesis markers are necessary [30,35].…”

“…Recent developments in CT-RSA have shown that CT-RSA has high potential to become an alternative to the classical marker-based RSA as it seems to have similar accuracy and it does not require markers or a calibration box. The main limitation of CT-RSA is the higher radiation dose [35]. In addition, artificial intelligence (AI), which is a very useful tool in image analysis [36], is rapidly developing to measure prosthesis migration in both CT [37] and standard clinical radiographs [38].…”

Comparison between model-based RSA and an AI-based CT-RSA: an accuracy study of 30 patients

“…The use of CT has for long been limited due to high radiation doses. With the advancement of low-dose technology [ 9 ], CT-based migration analysis—also known as CT-RSA [ 10 ]—is, however, now an attractive alternative to RSA, and different software programs are being evaluated. In theory, the CT-based approach enables easier patient follow-up and opens up the possibility for more hospitals to conduct research, as the demand for special RSA equipment and staff disappears.…”

A low-dose biplanar X-ray imager has RSA level precision in total knee arthroplasty

“…RSA currently uses conventional cone-beam radiography. To create registered images in such a system, 2 X-ray heads must be activated and a large reference object must be imaged simultaneously to calculate the X-ray head locations and define a coordinate system [ 1 ], or a higher dose CT-based system [ 12 ]. The requirement of a specific RSA suite with a large calibration object has limited the use of RSA.…”