Do fluoroscopy and postoperative radiographs correlate for periacetabular osteotomy corrections?

Background: The Bernese periacetabular osteotomy (PAO) can relieve pain and restore function in patients with symptomatic acetabular dysplasia. Accurate acetabular correction is fundamental to achieving these clinical goals and presumably enhancing survivorship of the reconstruction. Fluoroscopy is used by some surgeons to assess intraoperative acetabular correction but it is unclear whether the features observed by fluoroscopy accurately reflect those on postoperative radiographs. Questions/Purposes: We therefore determined whether the parameters of acetabular correction of PAO correlated on intraoperative fluoroscopic imaging and postoperative radiography. Methods: We retrospectively reviewed the imaging of 48 patients (50 hips) who underwent PAO. Intraoperative fluoroscopic AP and false profile images were obtained after final PAO correction. The intraoperative deformity correction as measured on the two fluoroscopy views was compared with the correction determined with postoperative standing plain AP pelvis and false profile radiographs using common measurements of acetabular position. Results: Of all radiographic parameters, lateral centeredge angle had the highest correlation between intraoperative fluoroscopy and the postoperative radiograph with an intraclass correlation coefficient (ICC) of 0.80 (0.68-0.88). Similarly, acetabular inclination and anterior center-edge angle also correlated with ICCs of 0.76 (0.61-0.85) and 0.71 (0.54-0.82), respectively. Extrusion index and medial offset distance had lower correlations with ICCs of 0.66 (0.46-0.79) and 0.46 (0.21-0.65), respectively. Conclusions: Intraoperative fluoroscopic assessment of PAO correction correlated with that from the postoperative radiographic assessment. Measurement of lateral centeredge angle shows the highest correlation with the fewest outliers. Acetabular inclination and anterior center-edge angle also correlated; extrusion index and medial offset distance should be used with more caution.