Iliosacral Screw Osteosynthesis

Abstract

Fragility fractures of the anterior pelvic ring are very often combined with fractures of the posterior pelvic ring. The large majority of the posterior fractures is situated in the sacral ala. Non-operative therapy may be cumbersome in patients with a combination of an anterior with a posterior pelvic ring fracture. Any surgical therapy should be as less invasive as possible. Iliosacral screw fixation is a minimal invasive technique. Variations of the upper sacral anatomy make optimal iliosacral screw placement challenging. The vestibule or isthmus is the narrowest part of the bony corridor from the lateral ilium to the S1 sacral body. It always points towards anterior and superior. The whole bone area for iliosacral screw placement has the form of a diabolo with the vestibule being its narrowest passage. Biomechanical studies showed that iliosacral screw fixation can achieve reliable stability, when combined with stable fixation of the anterior pelvic ring. The strength of cortical and trabecular bone is reduced in elderly persons, which influences the stiffness of iliosacral screw fixation. Long screws with their thread in the S1 sacral body are recommended. Transsacral implants, reaching from one sacroiliac joint to the other, provide higher stability than bilateral iliosacral screws in bilateral sacral fractures. High-quality fluoroscopic images of the injured pelvic side must be obtained before starting the surgical intervention. The patient can be placed in the supine or prone position. Iliosacral screw osteosynthesis is an adequate fixation technique for providing stability at the fracture site and reducing pain. With thorough preoperative planning and high-quality intraoperative imaging, iliosacral screw fixation is as safe in elderly patients as in younger adults. In case of bilateral lesions or complex fracture morphology, an adjunct osteosynthesis of the posterior pelvic ring is recommended.