Cement Augmentation in Sacroiliac Screw Fixation Offers Modest Biomechanical Advantages in a Cadaver Model

Abstract

Background Sacroiliac screw fixation in elderly patients with pelvic fractures is prone to failure owing to impaired bone quality. Cement augmentation has been proposed as a possible solution, because in other anatomic areas this has been shown to reduce screw loosening. However, to our knowledge, this has not been evaluated for sacroiliac screws. Questions/purposes We investigated the potential biomechanical benefit of cement augmentation of sacroiliac screw fixation in a cadaver model of osteoporotic bone, specifically with respect to screw loosening, construct survival, and fracture-site motion. Methods Standardized complete sacral ala fractures with intact posterior ligaments in combination with ipsilateral upper and lower pubic rami fractures were created in osteoporotic cadaver pelves and stabilized by three fixation techniques: sacroiliac (n = 5) with sacroiliac screws in S1 and S2, cemented (n = 5) with addition of cement augmentation, and transsacral (n = 5) with a single transsacral screw in S1. A cyclic loading protocol was applied with torque (1.5 Nm) and increasing axial force (250-750 N). Screw loosening, construct survival, and sacral fracture-site motion were measured by optoelectric motion tracking. A sample-size calculation revealed five samples per group to be required to achieve a power of 0.80 to detect 50% reduction in screw loosening. Results Screw motion in relation to the sacrum during loading with 250 N/1.5 Nm was not different among the three groups (sacroiliac: 1.2 mm, range, 0.6-1.9; cemented: 0.7 mm, range, 0.5-1.3; transsacral: 1.1 mm, range, 0.6-2.3) (p = 0.940). Screw subsidence was less in the cemented group (3.0 mm, range, 1.2-3.7) compared with the sacroiliac (5.7 mm, range, 4.7-10

Three-dimensional-guided navigation percutaneous screw fixation of fragility fractures of the pelvis

“…29 Published data from mechanical studies in cadaveric hip models are varied with cement-augmented sacroiliac screws shown to have similar to significantly higher construct stiffness and pull-out strength compared to uncemented screws. 30,31 In theory, bone union of the fracture surfaces are not jeopardized as they are spared of the cement, 29 but the long-term outcomes are uncertain due to paucity in clinical trials. A recent clinical trial demonstrated improved bone mass and reduced pedicle screw loosening with the use of teriparatide (human recombinant parathyroid hormone) for 6 months after spinal fusion compared to bisphosphonates alone.…”

In-screw polymethylmethacrylate-augmented sacroiliac screw for the treatment of fragility fractures of the pelvis: a prospective, observational study with 1-year follow-up

“…Thus, sacroiliac cement augmentation was introduced. Indeed, biomechanical examination failed to reveal the superiority of this technique in the hemipelvis model [ 33 – 35 ] the investigation of sole screw-sacral model yielded higher stability using augmented screws [ 36 ]. But so far, clinical trials using this technique especially regarding the outcome and pain are still sparse.…”

Safety, Effect and Feasibility of Percutaneous SI-Screw with and without Augmentation—A 15-Year Retrospective Analysis on over 640 Screws

“…However, the biomechanical results on the effect of augmentation are contradictory. Some authors found no difference between the augmentation of sacroiliac-screw and conventional sacroiliac-screw fixation [ 20 , 21 , 22 ]. Others report on improved biomechanical stability due to cement augmentation [ 23 , 24 , 25 ].…”