Abstract:

BACKGROUND: Acetabular cup orientation using a standard radiograph of the pelvis is quite common method to assess artificial hip replacement nowadays. Non-standardization of pelvic orientation affected accuracy of measurement results, and it is difficult to compare.

OBJECTIVE: To make sure how pelvis tilting affect the anteveration of the cup and to elevate clinical accuracy and compare study comparability.

METHODS: Designed a simulated acetabular cup with serial concentric circles which pass through the same polars and represent anteveration of 0°, 10°, 20°, 30°, 40°. Loaded the simulated acetabular cup at an inclination of 35°, 40°, 45°, 50°, 55° to 6 cadaver pelves. Made the pelves tilt around the frontal axis and sagittal axis with 5° each time in a scope of ± 30°. Take standard radiograph of the pelvis accordingly. Radiograph was photographed and frontal angle of dip was measured.

RESULTS AND CONCLUSION: Pelvic tilt of about 1° causes measuring errors of anteveration 0.61°-0.73°. The anteveration decreased at both acetabular cups when pelvic posterior tilt and at the acetabular cup that near the X-ray source as pelvic lateral tilt. The anteveration rose at both acetabular cups when pelvic anterior tilt and at the acetabular cup that away from the X-ray source as pelvic lateral tilt. During clinical evaluation, pelvic orientation effects on measurement results should be considered