Pelvic ring fractures internal fixation: iliosacral screws versus sacroiliac hinge fixation.

INTRODUCTION Pelvic ring fractures are severe injuries whose functional results depend on the quality of reduction. Numerous internal fixation alternatives have been described, but the biomechanical studies comparing them remain rare. HYPOTHESIS This study compared the biomechanical behavior of iliosacral screws (ISS) with sacroiliac hinge type fixation (SIF) following unstable pelvic ring fractures fixation. MATERIALS AND METHODS A lesion simulating sacroiliac disruption and pubic disruption was created on 14 cadaver pelves. After randomization, the fractures were internally fixed using an anterior plate associated with either an ISS or an SIF. The specimens were then submitted to forces applied vertically at the coxofemoral joints. Relative movements in vertical translation and in rotation between the iliac wing and the sacrum, as well as the stiffness and the forces at failure of the assemblies were measured and compared. RESULTS The mean age of the bodies was 66 years (+/-8). No significant difference was demonstrated between the groups in terms of residual motion and stiffness in both vertical and rotational displacement. The results showed a slight residual mobility in rotation of the hemipelvis. The SIFs presented greater, although non significant resistance to failure. No fixation, however, restituted stiffness comparable to a healthy pelvis. DISCUSSION The results of this study show that a Tile C.1.2-type injury to the pelvic ring can be treated as effectively with ISS or SIF when combined anterior and posterior fixations are performed. SIF therefore seems reliable and its continued use is justified. The long-term clinical outcomes should nevertheless be evaluated, notably on the younger population, more often affected by this type of injury.