Abstract
Hip dysplasia is characterized by insufficient femoral head coverage (FHC). Quantification of FHC is of importance as the underlying goal of the surgery to treat hip dysplasia is to restore a normal acetabular morphology and thereby to improve FHC. Unlike a pure 2D X-ray radiograph-based measurement method or a pure 3D CT-based measurement method, previously we presented a 2.5D method to quantify FHC from a single anteriorposterior (AP) pelvic radiograph. In this study, we first quantified and compared 3D FHC between a normal control group and a patient group using a CT-based measurement method. Taking the CT-based 3D measurements of FHC as the gold standard, we further quantified the bias, precision and correlation between the 2.5D measurements and the 3D measurements on both the control group and the patient group. Based on digitally reconstructed radiographs (DRRs), we investigated the influence of the pelvic tilt on the 2.5D measurements of FHC. The intraclass correlation coefficients (ICCs) for absolute agreement was used to quantify interobserver reliability and intraobserver reproducibility of the 2.5D measurement technique. The Pearson correlation coefficient, r, was used to determine the strength of the linear association between the 2.5D and the 3D measurements. Student’s t-test was used to determine whether the differences between different measurements were statistically significant. Our experimental results demonstrated that both the interobserver reliability and the intraobserver reproducibility of the 2.5D measurement technique were very good (ICCs > 0.8). Regression analysis indicated that the correlation was very strong between the 2.5D and the 3D measurements (r = 0.89, p < 0.001). Student’s t-test showed that there were no statistically significant differences between the 2.5D and the 3D measurements of FHC on the patient group (p > 0.05). The results of this study provided convincing evidence demonstrating the validity of the 2.5D measurements of FHC from a single AP pelvic radiograph and proved that it could serve as a surrogate for 3D CT-based measurements. Thus it may be possible to use this method to avoid a CT scan for the purpose of estimating 3D FHC in diagnosis and post-operative treatment evaluation of patients with hip dysplasia.
Highlights
Hip dysplasia is characterized by insufficient femoral head coverage (FHC) [1]
It has an inferior accuracy in comparison to three-dimensional (3D) techniques based on Computed Tomography (CT), it is used routinely because of its simplicity, availability, and minimal expense associated with its acquisition
In the first experiment we found that the 3D measurements of FHC varied from 57.9% to 80.2% on the normal control subjects
Summary
Hip dysplasia is characterized by insufficient femoral head coverage (FHC) [1]. Due to smaller weight-bearing surface and increased contact stresses, hip dysplasia has been implicated as a main cause of hip osteoarthritis (OA) [2, 3]. One of the most important goals of the surgical treatment of patients with hip dysplasia is to improve FHC and thereby to restore a normal acetabular morphology [5]. Two-dimensional (2D) anteriorposterior (AP) pelvic radiograph is the standard imaging means that is widely used in evaluating dysplastic hips. It has an inferior accuracy in comparison to three-dimensional (3D) techniques based on Computed Tomography (CT), it is used routinely because of its simplicity, availability, and minimal expense associated with its acquisition. Different standard geometric parameters were presented to quantify hip dysplasia, such as extrusion index [7], lateral center-edge angle (LCE) [8], anterior center edge angle (ACE) [9], and others [10]. Though easy to measure from an AP pelvic X-ray radiograph, all these parameters are indirect indicators for assessing FHC and their accurate interpretations are subjected to substantial errors if the individual pelvis orientation with respect to X-ray plate is not taken into consideration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
