The reliability and variation of acetabular component anteversion measurements from cross-table lateral radiographs

Although cross-table lateral (CL) radiographs are frequently used to assess acetabular component anteversion, the reliability of this method has not been established. We compared serial CL radiographs with computed tomography (CT) scans for 98 total hip arthroplasty patients (119 hips) undergoing surveillance of primary or revision total hip arthroplasty. Acetabular anteversion averaged 26.1° (range, -2° to 48.3°) on CL imaging and 28.8° (range, -7° to 54°) on CT scan. There was a strong correlation between anteversion determined from CT scans and serial CL images. However, variation on serial CL studies exceeded 10° for 20% of patients. Although CL imaging provides acceptable assessment of general component position, it has limited use for precise analysis in research, outcome reporting, or determination of cause of implant failure.