Evaluation of automated radiostereometric image registration in total knee arthroplasty utilizing a synthetic‐based and a CT‐based volumetric model

Abstract

Radiostereometic analysis (RSA) is an accurate method for rigid body pose (position and orientation) in three-dimensional space. Traditionally, RSA is based on insertion of periprosthetic tantalum markers and manual implant contour selection which limit clinically application. We propose an automated image registration technique utilizing digitally reconstructed radiographs (DRR) of computed tomography (CT) volumetric bone models (autorsa-bone) as a substitute for tantalum markers.Furthermore, an automated synthetic volumetric representation of total knee arthroplasty implant models (autorsa-volume) to improve previous silhouetteprojection methods (autorsa-surface). As reference, we investigated the accuracy of implanted tantalum markers (marker) or a conventional manually contour-based method (mbrsa) for the femur and tibia. The data are presented as mean (standard deviation). The autorsa-bone method displayed similar accuracy of −0.013 (0.075) mm compared to the gold standard method (marker) of −0.013 (0.085). The autorsavolume with 0.034 (0.106) mm did not markedly improve the autorsa-surface with 0.002 (0.129) mm, and none of these reached the mbrsa method of −0.009 (0.094) mm. In conclusion, marker-free RSA is feasible with similar accuracy as gold standard utilizing DRR and CT obtained volumetric bone models. Furthermore, utilizing synthetic generated volumetric implant models could not improve the silhouettebased method. However, with a slight loss of accuracy the autorsa methods provide a feasible automated alternative to the semi-automated method.

Dose reduction does not impact the precision of CT-based RSA in tibial implants: a diagnostic accuracy study on precision in a porcine cadaver

“…Furthermore, our results indicate that the precision achieved through the low-dose protocol surpasses that of RSA when assessing tibial implants [ 10 ]. The results in the Table also indicate that the lower precision in out-of-plane motions that RSA studies may be subject to is hardly relevant to CT-RSA [ 21 - 22 ].…”

Dynamic radiostereometry can objectively quantify the kinematic laxity patterns and rotation instability of the knee during a pivot‐shift test

“…The bone models were registered automatically to the bone structures in all dRSA images using the AutoRSA software and a two‐stage registration process (Figure 4) (AutoRSA Research Group, Orthopaedic Research Unit, Aarhus, Denmark) [10]. Briefly, the software utilises digitally reconstructed radiographs to estimate the model pose according to the dRSA images using a normalised gradient correlation approach [10, 41, 42, 50]. Approximately 45 dRSA images were analysed for each pivot‐shift test.…”

“…the dRSA images using a normalised gradient correlation approach [10,41,42,50]. Approximately 45 dRSA images were analysed for each pivotshift test.…”

Medial congruent polyethylene design show different tibiofemoral kinematics and enhanced congruency compared to a standard symmetrical cruciate retaining design for total knee arthroplasty—an in vivo randomized controlled study of gait using dynamic radiostereometry

“…The optimal model pose was found by minimizing the difference between the virtually generated projection image and the actual stereoradiographs using a normalized gradient correlation approach [5, 19]. The mathematical optimization algorithms, including the accuracy, have been described in more detail [7, 41]. The manufacturer supplied three‐dimensional triangular implant surface models containing approximately 5,000 vertices each.…”