Table 1 Inclusion and exclusion criteria

Age over 18

Age under 18

Treatment by MIS ISS for sacral fractures

 MIS ISS placement guided by fluoroscopy was included retrospectively

 MIS ISS placement guided by navigation was included prospectively

Treatment for other musculoskeletal problems than the sacral fracture in the same surgery (e.g. spinal instrumentation or symphysis plating)

Present implants in the area of the posterior pelvic ring before surgery

Complete set of data including pre- and postoperative CT scan and complete perioperative documentation of radiation use

Incomplete set of data

Written consent to participate

Missing consent to participate