Periacetabular osteotomy: validation of intraoperative fluoroscopic monitoring of acetabular orientation

During periacetabular osteotomy (PAO) the acetabulum is reorientated and the correction monitored by one or more anteroposterior pelvic radiographs. Obtaining these images is time consuming and requires additional technical and personal resources. Such disadvantages could be overcome with the use of fluoroscopy. However, information obtained from fluoroscopy should have the same quality when compared to standard pelvic radiography. Our purpose was to define a suitable fluoroscopy setup and compare the information obtained from the fluoroscopic images to that obtained from a traditional anteroposterior pelvic radiograph. In a consecutive series of 22 patients the acetabular fragment was monitored by a defined intraoperative fluoroscopy setup in addition to a pelvic radiograph. The images were analyzed in random order utilizing common parameters to judge the quality of acetabular orientation. Agreement between the two images was assessed using kappa statistics and compared to the intra-observer reliability obtained from an independent experienced hip surgeon reading the same set of pelvic radiographs on two occasions. In 5 patients the radiation exposure during both fluoroscopy and standard AP pelvic radiography was measured and compared. Agreement of angular measurements of acetabular coverage and version as well as qualitative parameters of acetabular orientation and position between fluoroscopy and pelvic radiographs was at least equal to the intra-observer agreement of an independent experienced hip surgeon reviewing the pelvic radiographs alone. Significantly less radiation exposure was recorded with the use of fluoroscopy when compared to traditional pelvic radiography. We conclude that the use of intraoperative pelvic radiographs during PAO procedures can be replaced by fluoroscopy without quality impairment