Difference Between 2 Measurement Methods of Version Angles of the Acetabular Component

We evaluated the relationship and the difference between measurements of version angles (VAs) of the acetabular components in total hip arthroplasty taken using 2 different methods. One VA was measured on an anteroposterior radiograph of the hip joint (VAP) and the other on a cross-table lateral radiograph (VCL) in 97 hips after surgery (clinical data) and 6 sawbone pelvic models (model data). There was a positive correlation between VAP and VCL for both data. Mean and standard deviation of the differences (VCL − VAP) between the 2 measurements were 5° ± 4.2° in clinical data and −0.01° ± 0.32° in model data. These differences on clinical data should be taken into consideration when comparing VAs in the literature using different measuring methods.