The S2-Alar-Iliac Screw for Pelvic Trauma

Abstract

Percutaneous sacro-iliac screw osteosynthesis is considered to be standard of care for most posterior pelvic ring fractures. However, special situations require alternative strategies for sufficient stabilization. In these cases, stabilization can often be achieved using posterior instrumentation e.g. using SIPS-screws (spina-iliaca-posterior-superior screws). However, this often leads to implant-related aggravation of the sometimes already critical soft tissue conditions after pelvic trauma. S2-Ala-Ilium screws (S2AI screws) are a suitable alternative. The starting point lies medial of the posterior superior iliac spine below the iliac level. It is almost in line with a potential spinal instrumentation and therefore usually causes fewer soft tissue problems. Although this technique has been widely used in spinal surgery in recent years, its use in orthopaedic traumatology is largely unknown. The possibilities but also the limitations of this technique for the treatment of injuries to the pelvis are illustrated by this retrospective case series.

Internal fixation for fragility fracture of pelvis in a patient with ankylosing spondylitis

“…Recently, there have been several reports on a technique of complete fixation in the pelvis for sacral fractures in FFP, avoiding spinopelvic fixation. These techniques are suitable for elderly patients, combining the S1 pedicle screw with the S2-alar-iliac screw or iliac screw for strong fixation in the pelvis [9] , [10] . However, there has been no report of its application to patients with AS.…”

Biomechanical Comparison of Five Fixation Techniques for Unstable Fragility Fractures of the Pelvic Ring

“…Lumbopelvic fixation in combination with a transiliac-transsacral screw resulted in the least amount of motion [23]. However, the used S1/S2 ala-ilium screws technique in this study was restricted to sacral fixation, without including the lumbar spine, as described elsewhere [12]. The S1/S2 ala-ilium screws were significantly superior in terms of cycles to failure, corresponding failure load, and initial axial stiffness compared to the posterior SI screw alone and to the SI screw plus supra-acetabular external fixator.…”

“…Gardner et al [28] demonstrated in their biomechanical study simulating a symphyseal and unilateral sacroiliac joint disruption in synthetic pelvises that a standard two-bar external fixation did not apply any compression across the sacroiliac joint. In a clinical study, the minimally invasive S2 ala-ilium screw fixation has been described as a successful treatment option for pelvic trauma [12]. This technique might be a successful treatment option for FFP type IIc.…”

“…Predrilling was performed with a 3.5 mm drill bit using a customised PMMA guide. In group 5-with no implementation of SI screw fixation-predrilling for the S1 pedicle screw insertion in the first sacral vertebral body was performed with a 5.0 mm drill bit, while predrilling for the S2 ala-ilium screw in the second sacral vertebral ala was performed with a 6.0 mm drill bit [12,13]. Fixation was achieved by inserting a 7.2 × 35 mm S1 pedicle screw and an 8.2 × 100 mm S2 ala-ilium screw, both made of titanium and connected with a 5.5 mm titanium rod (Silony Medical Europe GmbH, Bremen, Germany).…”

Biomechanical investigation of S2 alar‐iliac screw and S1 pedicle screw fixation in the treatment of Denis type II sacral fractures

“…Although the S2AI screw technique has been widely used in spinal surgery, its applicability to pelvic fractures is largely unknown. Only a small number of clinical studies 14–17 have applied S2AI screws to pelvic fractures, and there have been no reports of related biomechanical studies. For sacral fractures with stable lumbosacral joints (Isler type I), the purpose of surgery is only to resolve the pelvic instability, and thus the lumbar spine does not need to be fixed 2 .…”