Biomechanical Comparison of Standard Iliosacral Screw Fixation to Transsacral Locked Screw Fixation in a Type C Zone II Pelvic Fracture Model

Abstract

Fixation of unstable zone II sacral fractures using the combination of an iliosacral screw and a locked transsacral screw resists deformation and withstands a greater force to failure as compared to fixation with 2 standard iliosacral screws. This locked transsacral construct may prove advantageous, especially when a percutaneous technique is used for a Type C zone II vertically oriented sacral fracture injury pattern, which can result in residual fracture site separation.

Biomorphometric analysis of ilio‐sacro‐iliacal corridors for an intra‐osseous implant to fix posterior pelvic ring fractures

“…In a biomechanical study an increased fracture fixation strength of a 2‐screw fixation construct was observed, if one screw was placed trans‐sacral and locked with a nut on the opposite ilium . The study design did not clarify the reason for the more rigid fixation being either the counterlocking nuts or the engagement of additional cortices on the contralateral fracture side by the longer screw.…”

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves

“…Compared with the oblique sacroiliac screw fixation described by Matta and Saucedo [20], additional fracture pattern like central sacral fractures (Denis Zone III) and bilateral posterior pelvic lesions can be addressed through a unilateral approach, whereas alternative sacroiliac screw fixation from both sides was accompanied with an increased risk of screw misplacement [9,12]. Furthermore, in biomechanical studies, increased fixation strength for transsacral screw placement was reported owing to the screw placement in three additional cortices on the contralateral side instead of placing the screw tip in the weaker cancellous bone of the sacral ala and S1 vertebral body [18,33,39]. This seems particularly important in the increasing number of insufficiency fractures of the pelvic ring caused by osteoporotic bone quality [14].…”

“…Furthermore, increased fixation strength was reported for longer screws in biomechanical studies [18,33]. The drawback of transsacral screw fixation is the difficult placement owing to the individual variable three-dimensional anatomic shape of the sacrum (sacral dysmorphism), with several neurovascular structures in close proximity to the osseous boundary (S1 corridor: L4 and L5 nerve route and internal iliac vessels above and in front of the sacral alar region; S1 nerve route and the residual nerve pairs in the spinal canal below and posterior; S2 corridor: S1 foramen with its nerve route above and S2 foramen with its nerve route below) [3,7,34].…”

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

“…The setup and some of the loads applied in this study were chosen similar to those reported in published studies [24,33,39,43]. In addition, a stepwise increase in loads [12,40] was chosen to simulate the cyclic loading environment resulting from different levels of weightbearing (toe-touch, walking with a walker, full weightbearing) because they would be expected in the heterogeneous elderly population with fragility fractures of the pelvis with very different levels of balance, compliance, and pain.…”

“…Unlike other studies [24,40], we added anterior fixation with a retrograde transpubic screw [14] in all specimens. In the clinical context of an osteoporotic lateral compression fracture, the use of additional anterior fixation might be controversial; in the case of our cadaver model, the function of this anterior implant was to standardize and account for the missing soft tissues that usually stabilize the anterior pelvic ring.…”