Optimal Pelvic Inlet and Outlet Radiograph Angles in Korean Patients / 대한정형외과학회잡지

ABSTRACT

PURPOSE: Until now, pelvic injuries have been evaluated with 45degrees inlet and 45degrees outlet radiographs. Following these customary guidelines may not produce the best plane to evaluate pelvic injury due to variability of pelvic anatomy. Recent data based on the American population suggested 25degrees and 60degrees as the optimal angle for each inlet and outlet views, respectively. We hypothesized that inlet and outlet radiographic views to examine the clinically relevant landmarks vary from routine 45degrees inlet and outlet views and aimed to find optimal angles for Korean patients. MATERIALS AND METHODS: One hundred consecutive patients, aged between 30 to 60 years (50 male and 50 female patients), without pelvic ring disruption or fractures who had undergone routine axial pelvic computed tomography scans were retrospectively identified. The optimal inlet and outlet angles required to profile the clinically relevant pelvic anatomy were quantified for each patient. RESULTS: The optimal inlet angle to profile the anterior body of S1 and S2 required an average caudal tilt of 24.2degrees and 27.9degrees, respectively. The average outlet angle perpendicular to the body of S1 was 54.8degrees and perpendicular to S2 was 52.3degrees. The optimal angles were the same for male and female patients and were independent of patient age. CONCLUSION: Screening inlet and screening outlet radiographs made at 25degrees and 55degrees, respectively, are recommended for viewing clinically relevant osseous pelvic anatomy in Koreans.