Cup positioning in THA: current status and pitfalls. A systematic evaluation of the literature

Abstract

The correct determination of cup orientation in THA regarding the intraoperative as well as the postoperative assessment due to the pelvic tilt and rotation with inexact incorporation of the pelvis is uncertain. The anterior pelvic plane (APP) seems to be the most reliable reference frame and computer-assisted navigation systems seem to provide the best tool for correct implantation to date. For the intraoperative assessment of the APP, the exact determination of the bony landmarks is mandatory. For the standard plain radiography, standardized positioning of the patient and approximation of pelvic tilt by a lateral view are mandatory. An additional CT must be carried out for certain indications. More emphasis has to be given to the individuality of pelvic tilt and range of motion.

Statistically Deformable 2D/3D Registration for Estimating Post-operative Cup Orientation from a Single Standard AP X-ray Radiograph

“…Previously, several studies 2,4,22,31,33 have suggested that CT-based methods seem to be the most reliable method for noninvasive post-operative assessment of the acetabular cup orientation with experienced and trained observers. Nevertheless, intra-and inter-observer variability is still present.…”

“…Previous studies 42,64 reported that the errors in measuring the cup anteversions with the radiographic measurement method could be as high as 20°. On the other side, post-operative CT-based methods, which are regarded as the most reliable methods for measuring post-operative cup orientation, 2,4,22,31,33 are not widely be used in clinical routine because they require not only the additional expense but also the additional radiation doses to the patient. The recently introduced CT-based 2D/3D rigid image registration methods 8,20,28,42,64,65 have shown reasonably accurate results in calculation of post-operative cup orientation.…”

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

“…A gonadal shielding during diagnostic X-ray procedure is an effective way of reducing radiation dose to patient's reproductive organs to decrease the risk of genetic effects in future generations 26 . However, the utilization of the gonadal shielding also causes the occlusion of a big portion of the Xray radiograph, which poses a challenge to the intensity-based 2D-3D registration.…”

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

“…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. As long as there is a CT study of the patient during treatment, the present technique can be used to accurately and reliably measure the post-operative cup orientation and the pelvic tilt and rotation.…”