Assessing the Accuracy Factors in the Determination of Postoperative Acetabular Cup Orientation Using Hybrid 2D–3D Registration

Abstract

Single standard anteroposterior radiograph-based methods for measuring cup orientation following total hip arthroplasty (THA) are subject to substantial errors if the individual pelvic orientation with respect to X-ray plate is not taken into consideration. Previously, we proposed to use a hybrid 2D-3D registration scheme to determine the postoperative acetabular cup orientation and developed an object-oriented cross-program called "HipMatch." However, its accuracy and robustness have not been fully investigated. To assess the potential factors that may affect the accuracy and robustness of the hybrid 2D-3D registration scheme in determining the postoperative acetabular cup orientation, a comprehensive validation study using a cadaver pelvis was performed. Nine X-ray radiographs taken from different pelvic positions relative to the X-ray plate and two computed tomography volumes of the pelvis with one acquired before the cup implantation and the other acquired after the cup implantation were used in the validation study. Potential factors that may affect the accuracy and robustness of the hybrid 2D-3D registration scheme were experimentally determined. Our experimental results demonstrate that (1) the plain radiograph-based method is not accurate; (2) the hybrid 2D-3D registration scheme helps to improve the estimation accuracy; (3) the hybrid 2D-3D registration scheme can robustly and accurately estimate the cup orientation even when a big portion of the radiograph is occluded; and (4) image resolution has minor effect on the estimation accuracy. The hybrid 2D-3D registration scheme is an accurate and robust method to measure exact cup orientation in THA. It holds the promise to be a valuable tool for clinical routine usage for providing evidence-based information.

Computer assisted determination of acetabular cup orientation using 2D–3D image registration

“…The results of the experiments that were conducted on datasets of ten cadavers (20 hips) demonstrated that the present technique was apparently more accurate than the radiographic measurement method. The substantial error range (from 0.2 • to 15.2 • ) as found in measuring anteversion using the radiographic measurement method [11] in this study is coincident with other recently published findings that the radiographic measurement of anteversion is unreliable [8][9][10][13][14][15]24,25]. The advantages of the present technique over other methods for post-operative calculation of acetabular cup orientation are apparent.…”

“…The advantages of the present technique over other methods for post-operative calculation of acetabular cup orientation are apparent. Several studies [8][9][10][13][14][15]24,25], including the one presented in this paper, have shown that the radiographic measurement methods, though easy to use, cannot produce accurate results due to the wide variability in individual pelvic orientation relative to X-ray plate during image acquisition. Post-operative CT-based method, which is regarded as the most reliable method for measuring post-operative cup orientation [8][9][10][13][14][15]34,35], cannot be used in clinical routine due to the additional expense and radiation doses to the patient associated with its acquisition.…”

“…It was suggested by Wan et al [37] that the common measurements used for reporting compute navigation and CT scan values should be the radiographic coronal plane because of the reason that surgeons were familiar with the measurement numbers of the radiographic coronal plane of plain radiographs. However, the reality is that most of the available studies on computer navigation based or CT scan-based measurements are done with respect to the anterior pelvic plane without considering the pelvic tilt [8][9][10]15,[18][19][20][21][22]24,25,33,34,36], although the influence of the pelvic tilt on anteversion and inclination of the acetabular cup has drawn more and more attentions [37][38][39][40][41][42]. The present method, which allows for computing the pelvic tilt and rotation with respect to the X-ray imaging plane/plate by performing a 2D-3D registration between a CT scan of the patient and a post-operative X-ray radiograph, can be used as a tool to convert the results measured with respect to the anterior pelvic plane to those measured with respect to the radiographic coronal plane.…”

“…Based on this new formulation, we developed an object-oriented program and conducted a preliminary evaluation [24]. Accuracy factors in the determination of post-operative cup orientation using the developed program was also assessed using experiments conducted on one cadaver pelvis [25]. In this paper, we focus on describing the details of the hybrid 2D-3D registration scheme and on evaluating the influence of different registration strategies on the determination accuracy by performing a comprehensive study on ten cadavers (20 hips).…”

Computer‐aided pelvic reduction frame for anatomical closed reduction of unstable pelvic fractures

“…Because projecting the 3D pelvic geometry onto a 2D plane may not reflect the accurate position of the pelvis, particularly the complex posterior rings, researchers have tried to develop more advanced methods for determining the 3D position using 2D imaging tools. Previous image registration and processing methods have used pre‐operative 3D CT reconstruction and intra‐operative radiography, particularly in spinal and arthroplastic surgery‐related research . Hufner et al performed image registration based on the regular shape of the external fixture, which could improve the accuracy of the registration and spatial orientation.…”