Radiographic Examination at Lateral Decubitus Position for Reducing the Variability of Cup Inclination / 대한정형외과학회잡지

ABSTRACT

PURPOSE: This study analyzed the factors related to a variable inclination angle in patients who have undergone total hip arthroplasty by taking pelvis AP X-rays in the lateral decubitus position with a 45degrees targeted goniometer. MATERIALS AND METHODS: We recruited 100 adults (50 men and 50 women) who were without a history of hip joint disease. The mean age was 30.1 years for the men and 33.7 years for the women. The circumferences of the shoulder and pelvis, the shoulder to pelvis ratio, and the body mass index were checked. We examined the radiographs with using a goniometer, which was targeted to 45degrees for allowing a rod to be across the center of the acetabulum. The cross angle between the rod and the interteardrop line was checked. RESULTS: On the comparison of the gender groups, the shoulder to pelvis ratio was on average 1.18 in men and it was 1.08 in women. The mean cross angle was 45.3degrees in men and 48.1degrees in women. As the ratio was increased, the cross angle decreased. CONCLUSION: For men, there was little pelvic tilt in the lateral decubitus position. But for women, if inserting the acetabular cup with the acetabular orientation at 45degrees is done without considering the pelvic tilt inclination at the lateral decubitus position, then the inclination angle could be lower than expected.