Introduction: The literature has recently underlined the interest of pelvic and acetabular component orientation measurements in the standing and sitting position. Radiographic follow-up of total hip arthroplasty (THA) is based on standard AP and lateral X-rays. The use of EOS™ 2D imaging system reduces patient's radiation exposure compared to conventional X-rays. However, using this system, the validity and reproducibility of angular measurements, have not been studied yet for the measurement of pelvic and acetabular parameters in patients with THA. Hypothesis: The EOS™ 2D imaging system offers similar advantages to conventional X-rays in the measurement of pelvic and acetabular orientation parameters which are commonly used. Patients and method: Five angular parameters characterizing pelvic tilt and acetabular cup orientation were determined using the same digital measurement Imagika™ software based on two series of standard X-rays and EOS™ 2D images acquired in both standing and sitting positions. Radiographs from 50 patients with unilateral THA were measured three times by two observers. Intra- and interobserver reproducibility using each method was independently studied then paired comparison was performed. Results: The ICC and Spearman rank correlation coefficient demonstrated an excellent EOS/conventional X-ray correlation. According to the parameters, the mean difference between these two imaging modalities ranged from 0.30° to 3.43° (P<. 0.05). The intra- and interobserver variability ranged from. ±. 2.97° to. ±. 6.46° using the EOS™ imaging system and from. ±. 4.26° to. ±. 10.22° using conventional X-rays (P<. 0.05). Discussion: The EOS™ 2D imaging system may replace conventional X-rays in the assessment and monitoring of pelvic and acetabular cup orientation in THA. Level of evidence: Level III. Prospective diagnostic study. © 2011 Elsevier Masson SAS.
Lazennec, J. Y., Rousseau, M. A., Rangel, A., Gorin, M., Belicourt, C., Brusson, A., & Catonné, Y. (2011). Pelvis and total hip arthroplasty acetabular component orientations in sitting and standing positions: Measurements reproductibility with EOS imaging system versus conventional radiographies. Orthopaedics and Traumatology: Surgery and Research, 97(4), 373–380. https://doi.org/10.1016/j.otsr.2011.02.006