Biomechanical study of transsacral-transiliac screw fixation versus lumbopelvic fixation and bilateral triangular fixation for “H”- and “U”-type sacrum fractures with traumatic spondylopelvic dissociation: a finite element analysis study

Abstract

Objective To compare the biomechanical stability of transsacral-transiliac screw fixation and lumbopelvic fixation for “H”- and “U”-type sacrum fractures with traumatic spondylopelvic dissociation. Methods Finite element models of “H”- and “U”-type sacrum fractures with traumatic spondylopelvic dissociation were created in this study. The models mimicked the standing position of a human. Fixation with transsacral-transiliac screw fixation, lumbopelvic fixation, and bilateral triangular fixation were simulated. Biomechanical tests of instability were performed, and the fracture gap displacement, anteflexion, rotation, and stress distribution after fixation were assessed. Results For H-type fractures, the three kinds of fixation ranked by stability were bilateral triangular fixation > lumbopelvic fixation > transsacral-transiliac screw fixation in the vertical and anteflexion directions, bilateral triangular fixation > transsacral-transiliac S1 and S2 screw fixation > lumbopelvic fixation in rotation. The largest displacements in the vertical, anteflexion, and rotational directions were 0.57234 mm, 0.37923 mm, and 0.13076 mm, respectively. For U-type fractures, these kinds of fixation ranked by stability were bilateral triangular fixation > lumbopelvic fixation > transsacral-transiliac S1 and S2 screw fixation > transsacral-transiliac S1 screw fixation in the vertical, anteflexion, and rotational directions. The largest displacements in the vertical, anteflexion, and rotational directions were 0.38296 mm, 0.33976 mm, and 0.05064 mm, respectively. Conclusion All these kinds of fixation met the mechanical criteria for clinical applications. The biomechanical analysis showed better bilateral balance with transsacral-transiliac screw fixation. The maximal displacement for these types of fixation was less than 1 mm. Percutaneous transsacral-transiliac screw fixation can be considered the best option among these kinds of fracture fixation.

Incidence of and Risk Factors for Screw Loosening after Iliosacral Screw Fixation for Posterior Pelvic Ring Injury

“…The modes of fixation for posterior pelvic ring injuries include the screws being inserted only in S1 or in S1 and S2. It has been suggested in biomechanical studies that screw fixation in a double‐layer sacral has higher stability than a single layer, 33,34 and several clinical studies 10,12 obtained the same result, which supported our conclusion that the screw insertion only at the level of S1 had a higher incidence of screw loosening than that inserted at the level of S1 and S2.…”

Effective treatment of highest instability in a subacute fragility fracture of the pelvis (FFP IV) using a cement augmented transsacral screw only

“…Formal indications of either method have been recently suggested but are not yet widely adopted in clinical practice [3] , [4] , [5] . In traumatic H-/U-type fractures, finite element analyses revealed that LPS is superior to transsacral fixation in terms of translational and rotational stability [6] . Thus, from a biomechanical perspective, single-level transsacral fixation may be considered insufficient in H-/U-type FFP.…”

Surgical Management of Unstable U-Shaped Sacral Fractures and Tile C Pelvic Ring Disruptions: Institutional Experience in Light of a Narrative Literature Review

“…Non-displaced U-shaped sacral fractures (AO Spine C0) without neurological deficits can be managed conservatively if the patient suffers from other lesions requiring bed rest. Orthopedic treatment or iliosacral screws can be indicated for slightly displaced Roy-Camille type 1 U-shaped sacral fractures [ 7 , 56 ]. Type 2 and 3 U-shaped sacral fractures (equivalent AO Spine C3) frequently require surgical stabilization.…”