Laser Projector Method for Measuring Postoperative Acetabular Anteversion After Total Hip Replacement
Wei-Cheng Chen, Tai-Yin Wu, Kuan-Yu Chi, Pei-Wei Weng, Yu-min Huang, Feng-Huei Lin, Chen-Kun Liaw
Introduction For patients undergoing total hip replacement (THR), measuring the postoperative acetabular anteversion precisely plays a pivotal role in the prognosis because anteversion of acetabulum cup determines the range of motion and stability after the THR. To date, the documented techniques for the accurate assessment encompass methods of two-dimensional (2D) and three-dimensional (3D). Our team has developed several 2D methods for precisely measuring acetabular anteversion after the THR,
... namely the trigonometric, the protractor, and the computerized ellipse method. Despite multiple commercially available assessing tools, most mandate computerized equipment with corresponding software that is frequently in shortage in remote areas and developing countries. Therefore, we attempted to invent a laser projector that is able to measure the acetabular anteversion directly on the traditional plain film and to examine its validity and consistency by comparison with the Elliversion software.Methods We invented a portable laser projector incorporating the ellipse method for the measurement of postoperative acetabular anteversion. We retrospectively collected 50 postoperative pelvis radiographs including acetabulum from our institution. One investigator first measured the anteversion of included radiographs through Elliversion software as the control group. Subsequently, two operators independently used the laser projector for measurements in two separate periods with 1-day intervals as the experimental group. Our analysis was comprised of intra- and inter-group comparisons, which investigated the consistency and validity, respectively, by using two-sample student's t-test. P-value < 0.05 suggests statistical significance. Results There was no significant difference in measuring the anteversion through laser projectors between two operators (MD, -0.12; 95% CI, -0.52 to 0.27; p=0.54). The estimated effect in the anteversion measurement between the Elliversion and laser projector was also comparable (MD, -0.17; 95% CI, -0.38 to 0.04; p=0.12).Conclusions Our study reported the consistency and validity of this laser projector as there is no significant difference in both intra- and inter-observer reliability, demonstrating real-time, intuitive, and convenient product design comparing to Elliversion. Most importantly, we look forward to helping elevate clinical acumen when doctors provide care to patients after THR, especially in remote areas.