A New Method To Measure Acetabular Prostheses Anteversion From Anteroposterior Radiographs

Objective: To design a new and simplified method for total hip arthroplasty in the measurement of anteversion angle from anteroposterior radiographs and evaluate the accuracy.Method: The simulated anteroposterior radiographs at various acetabular prostheses anteversion were projected.Anteversion of the acetabular prostheses was measured by three examiners using ourself-designed method on anteroposterior radiographs,and the accuracy of the method was evaluated by comparing the measurements with standard anteversions.A examiner compared the measurements with standard anteversions using ourselfdesigned method and four reported different methods(Lewinneck,Hassan,Liaw,Pradhan)and evaluated the accuracy of five methods.Acetabular prostheses anteversion were studied in 27 patients with 27 hip joint shooting computed tomography(CT)and X-ray films with total hip arthroplasty in the third hospital of hebei medical university.CT measurement was regarded as the gold standard,and the accuracy of measurements with the CT measurements and the X-ray film measurements using ourself-designed method by a examiner were compared to evaluate the accuracy of the measurements using ours method on X-ray films.The simulated pelvic radiographs and acetabular radiographs were projected and the measurement divergence between hip-centered and symphysis-centered was compared using ourself-designed method by a examiner.Result:1.The error of the three measurement results and standard anteversion are respectively(0.04±0.57),(0.07±0.47),(0.11±0.55).Measurements by ourself-designed method were not significantly statistical different from standard anteversion(P>0.05).2.A examiner compared ourself-designed method with four reported different methods(Lewinneck,Hassan,Liaw,Pradhan)and certified that Lewinneck,Liaw and ourself-designed method were accurate,the others are not accurate.The error of the measurements and standard anteversion of two methods(Lewinneck,Liaw)respectively(-0.09± 0.42),(0.21±0.60),the measurements with the standard anteversion compared no significant difference(P>0.05).The error of the measurements and standard anteversion of two methods(Hassan,Pradhan)respectively(1.14± 0.87)and(1.48±1.24),the measurements with the standard anteversion compared with significant differences(P<0.05).3.Measurements using ourself-designed method on X-ray films were not significantly statistical different from CT measurements(P>0.05).4.The measurements of hip-centered images using ourself-designed method was larger symphysis-centered images.They did not have simple linear correlation,the divergence of them in 3.16-5.88 degree range.We thought the standard anteversion did not be equal to the measurements in the symphysis-centered images by adding a simple number.Conclusion: Ourself-designed method to measure acetabular prostheses anteversion is accurate.Comparsion with the four reported different methods(Lewinneck,Hassan,Liaw,Pradhan),the measurements of ourself-designed method is accurate,smaller measurement error,simpler measurement process and ours method provides a choice for clinical work to measurement acetabular prostheses anteversion.