Comparison of 2.5D and 3D Quantification of Femoral Head Coverage in Normal Control Subjects and Patients with Hip Dysplasia

Hui Cheng; Li Liu; Weimin Yu; Hong Zhang; Dianzhong Luo; Guoyan Zheng

doi:10.1371/journal.pone.0143498

Comparison of 2.5D and 3D Quantification of Femoral Head Coverage in Normal Control Subjects and Patients with Hip Dysplasia

PLoS One. 2015 Nov 24;10(11):e0143498. doi: 10.1371/journal.pone.0143498. eCollection 2015.

Authors

Hui Cheng^{1

2}, Li Liu², Weimin Yu², Hong Zhang¹, Dianzhong Luo¹, Guoyan Zheng²

Affiliations

¹ Division of Joint Surgery, Dept. Orthopaedic Surgery, The First Affiliated Hospital of PLA General Hospital, Beijing, China.
² Institute for Surgical Technology and Biomechanics, University of Bern, CH-3014, Bern, Switzerland.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Case-Control Studies
Femur Head / diagnostic imaging*
Hip Dislocation / diagnostic imaging*
Hip Dislocation / pathology*
Humans
Imaging, Three-Dimensional*
Observer Variation
Reproducibility of Results
Tomography, X-Ray Computed / methods*

Grants and funding

This work was partially supported by Sino-Swiss Science and Technology Cooperation Program, EG 11-032014 (GZ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.