DIFFERENCES IN RADIOGRAPHIC MEASUREMENTS ON STANDING VERSUS SUPINE PELVIC RADIOGRAPHS

摘要

Background: Accurate pelvic radiographic measurements is of clear clinical importance, as these measurements can drive the indications for surgery, the surgical approach utilized, and/or the degree of correction during hip preservation surgery. Currently, there are a large number of measurements available and reported on the literature when referencing anterior-posterior (AP) pelvic radiographs. However, there is no standardization of whether these pelvic radiographs are obtained in the standing or supine position. Hypothesis/Purpose: Standing vs. Supine radiographs, obtained in the same patient, will result in different value for standard radiographic measurements used in making hip pathology diagnoses. Methods: All new patients who presented for evaluation of hip pain between September 2016 and July 2018 were retrospectively reviewed. Inclusion criteria included age 18-50, no prior hip surgery/injury, and both standing and supine AP pelvis radiographs dated within 2 years of each other. Measurements were obtained on 26 radiographs (52 hips), blinded to patient demographics and standing versus supine radiograph. Measurements included minimum joint space, lateral center edge angle (LCEA), acetabular depth, acetabular inclination, T?nnis Grade, crossover sign, posterior wall sign, ischial spine sign. Results: Standing films resulted in significantly lower LCEA and acetabular depth measurements, and higher acetabular inclination. Supine measurements for crossover sign were 5.69 times more likely to be positive than standing measurements. Similarly, supine measurements for ischial spine were 7.93 times more likely to be positive (see Table 1). Conclusion: Based on our study, supine films are almost 6 times more likely to give a positive crossover sign and almost 8 times more likely to give a positive ischial spine sign than a standing film in the same patient. Additionally, LCEA, acetabular depth will be lower and acetabular inclination will be higher on standing films. As such, our recommendation is to obtain standing AP pelvis radiographs to obtain the most accurate pelvic radiographic measurements in hip preservation patients. Tables: Table 1. Radiographic measurements on standing and supine AP pelvis radiographs. Measurement LSmean Standing LSmean Supine p-value Min joint space 3.84 (0.18) 4.00 (0.18) 0.29 LCEA-ischium 23.45 (1.22) 24.94 (1.22) 0.007 LCEA- teardrops 24.09 (1.29) 25.35 (1.29) 0.01 Acetabular depth 9.40 (0.55) 10.94 (0.55) &0.001 Acetabular inclination 11.44 (0.78) 10.41 (0.78) 0.02 Measurement Odds Ratio for Modality 95% CI p-value T?nnis Grade 0.47 (0.26) 0.16, 1.40 0.18 X-over 5.69 (2.89) 2.10, 15.42 &0.001 Posterior Wall 2.55 (1.30) 0.94, 6.92 0.07 Ischial Spine 7.93 (6.73) 1.51, 41.80 0.01