Manual postoperative CT calculation of anteversion and inclination of the acetabular cup can be inaccurate and depends on the observer's experience. The aim of this study is to describe and present a validation of a new CT-image-based dedicate software (EGIT) for calculation of the acetabular component placement. The software principle is based on a three-dimensional reconstruction of a patient's bones from anatomical data collected postoperatively on the patient's CT scan. 15 Patient to be operated for THR were enrolled in this study. All patients were evaluated with post operative CT-scan. Measurement of Cup positioning were performed with two different methods: a manual method, performed by an expert radiologist, and a software CT image based method. Statistical analysis was performed with Intraclass Correlation Coefficent to asses interobserver and intraobserver reliability. A paired T-test was used to detect differences between manual and software methods. The Intraclass Correlation Coefficient was excellent for both the intraobserver and interobserver reliability. As expected the ICC is higher in the interobserver case. A mean cup anteversion of 14.2 (S.D. ±6.9), mean inclination of 44.2 (S.D.± 5.8) are detected with EGIT by the expert surgeon; Mean Cup anteversion of 13.6 (S.D. ± 5.11), mean inclination of 43.3 (S.D.± 5.1) are detected with manual method by expert radiologist. No statistical difference have been found (P> 0.05). The EGIT software seems to be an easy, accurate and reproducible method to calculate acetabular cup positioning using standard post-operative CT scan in THA.
