The purpose of this study is to compare the precision of computer-assisted navigation for hip screw implantation to conventional fixation without navigation.

Standard treatment for sacroiliac dislocations and sacroiliac fractures is placement of two screws through the iliosacral joint into the sacral ala or the body of the S1 vertebra. Correct positioning is technically demanding. Screw displacement may reduce the strength of fixation and lead to neurological complications.

Secondary objectives of the study are to compare the fluoroscopy time, complications and surgery duration between the treatments.

Inclusion Criteria:

• Radiologically confirmed sacroiliac dislocation or sacroiliac fracture
• Sacroiliac arthritis
• Age 18 years and more
• Written informed consent by patient or his/her legal representative

Exclusion Criteria:

• Poor life expectancy (<3months)
• Fracture of pathologic origin
• History of substance abuse (recreational drugs, alcohol)within 12 months prior to screening
• Prisoner
• Currently involved in another study that precludes or complicates participation
• Disease or condition that would preclude accurate evaluation (e.g., significant psychiatric disease)