Acetabular orientation in triple pelvic osteotomy: is intraoperative fluoroscopy reliable?

In pelvic osteotomies, unfavorable balancing of the anterior and posterior acetabular wall can affect the longevity of the natural joint. This raises the question, whether intraoperative fluoroscopy is sufficiently accurate. The objective was to assess the correlation between acetabular parameters [lateral center edge angle (LCEA), acetabular index (AI), anterior wall index (AWI), posterior wall index (PWI)] acquired on intraoperative fluoroscopic images and postoperative pelvic radiographs and to analyze intra- and interobserver reliability of these parameters.

A retrospective examination was conducted on 206 consecutive cases (176 patients) after triple pelvic osteotomy (TPO). Every patient received a pre- and postoperative pelvic radiograph in supine position in exactly the same technique. A highly standardized surgical sequence allowed consistent intraoperative fluoroscopic imaging. LCAE, AI, PWI and AWI were measured by an experienced orthopedic surgeon and an orthopedic surgeon in training. Statistics comprised a priori power analysis, Bland-Altman analysis and intraclass correlation coefficient (ICC).

A total of 165 cases were included. ICC between the parameters of the fluoroscopic images and postoperative radiographs was for LCEA: 0.935, AI: 0.936, AWI: 0.725 and PWI: 0.878. Intraobserver ICC for all parameters ranged from 0.953 to 0.989, interobserver ICC from 0.798 to 0.968, respectively.

In the surgical treatment of hip dysplasia by means of TPO, intraoperative fluoroscopic imaging has proven to be reliable and accurate. Intraobserver correlation was excellent for all parameters. The correlation between the intraoperative fluoroscopic images and postoperative radiographs ranged from good to excellent, with the lowest values for the acetabular wall indices (AWI and PWI).