Biomechanical stability of sacroiliac screw osteosynthesis with and without cement augmentation.

BACKGROUND: Percutaneous sacroiliac (SI) screw fixation is the standard operative treatment of traumatic disruptions to the posterior pelvic ring. The technique offers good outcomes and early postoperative mobilization, which is vital in elderly patients with fragility fractures of the pelvis. While a double-screw technique has been shown to provide optimal biomechanical stability compared to a single-screw construct, anatomic variations and patient-specific characteristics may prevent the safe insertion of two SI screws. We aimed to determine whether cement augmentation of a single SI screw would provide biomechanical stability comparable to that of the double-screw technique.
METHODS: Three sacroiliac screw osteosynthesis configurations were tested on 10 human cadaveric pelvis specimens: a single cannulated screw; two cannulated screws; and a single, cement-augmented cannulated screw. Displacement and stiffness of the anterior and posterior pelvic ring after fixation with each technique were measured under axial load. Results where compared using linear regression and paired t-tests.
RESULTS: A single uncemented screw offered significantly worse stability in the anterior pelvis compared to a double-screw technique (P < 0.05) and to a single cement-augmented screw technique (P < 0.05). There was no significant difference in anterior pelvic ring stability between the single cement-augmented screw technique and the double-screw technique (P > 0.05). There was no significant difference in the stability of the posterior pelvic ring between the three techniques (P > 0.05).
CONCLUSIONS: A single cement-augmented cannulated sacroiliac screw provides biomechanical stability similar to that of a non-augmented double-screw technique in the treatment of posterior pelvic ring fractures.