Incidence of delayed union one year after peri-acetabular osteotomy based on computed tomography

Background Pubic bone nonunion and delayed union are reported as post-operative complications after peri-acetabular osteotomy (PAO). However, few studies have determined the incidence of delayed union using computed tomography (CT) scans. This study aimed to determine the incidence of delayed union at one year after PAO using X-ray and CT scans. Methods We performed a retrospective review of 150 hips in 132 consecutive patients with acetabular dysplasia who underwent PAO between January 2012 and June 2016 and evaluated 107 hips for which pelvic CT scans taken at one year after PAO were available. Clinical evaluations included age at surgery, weight, body mass index (BMI) and history. Radiographic evaluations were to assess pubic, ischial and iliac delayed union at one year post-operatively. Results Based on X-ray analysis, the incidence of delayed union in the pubic, ischial and iliac bones was 11.2% (12 hips), 5.6%(6 hips) and 0% (0 hips), respectively, and 20.6% (22 hips), 8.4% (9 hips) and 0% (0 hips), respectively, based on CT scans. Conclusion The incidence of delayed union of the pubis and ischium at one year after PAO according to CT scans was higher than that based on X-ray imaging. CT scans are useful in patients with some symptoms at the osteotomy site.