Computed tomography measurement of acetabular cup anteversion and retroversion in total hip arthroplasty.

In a clinical study conducted between March 1983 and July 1987, computed tomography of the hip was employed with specially designed software in 20 patients after 23 total hip arthroplasties (THAs). Three patients had bilateral THAs. Computed tomography was performed in the routine manner, except that the image was reconstructed utilizing software that eliminated the metallic artifacts. The angle of the acetabular cup is determined on a display console. The cursor is turned on, one pole of the cup is marked, and when the second moving cursor is positioned on the opposite pole, the angle is shown and measured on the console. This technique has been indispensable for accurate measurement of the angle of inclination of the acetabular cup and in treatment planning in patients with a dislocating total hip prosthesis.