Combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability

Abstract

<jats:p>Lumbosacropelvic pseudarthrosis after long spinal fusions for treatment of adult degenerative scoliosis remains a challenging condition. Moreover, although pelvic fixation with iliac screws is widely used in deformity surgery to provide a biomechanically strong distal anchor for long thoracolumbar constructs, there are very few options available after failed pelvic fixation with iliac screws. The authors conducted a retrospective review of the surgical charts and imaging findings of patients subjected to revision surgery for lumbosacropelvic pseudarthrosis from August 2011 to August 2012. This review identified 5 patients in whom a salvage technique combining both S-1 and S-2 sacral alar-iliac (SAI) screws had been performed. In this technical note, the authors present a detailed anatomical discussion and an appraisal of the sequential intraoperative steps of this new technique involving a combination of S-1 and S-2 SAI screws. The discussion is illustrated with a surgical case in which this technique was used to treat a patient with pseudarthrosis that had developed after fixation with classic iliac screws. In conclusion, although S-2 SAI screws have previously been reported as an interesting alternative to classic iliac wing screws, this report is the first on the use of combined S-1 and S-2 SAI screws for pelvic fixation as a salvage technique for lumbosacropelvic instability. According to the reported experience, this technique provides a biomechanically robust construct for definitive pelvic fixation during revision surgeries in the challenging scenarios of pseudarthrosis and instability of the lumbosacropelvic region.</jats:p>

Sacroiliac joint variation associated with diffuse idiopathic skeletal hyperostosis

“…Further, numerous studies have reported that surgical treatment for traumatic spine fracture accompanying DISH often requires multi-level fusion to avoid postoperative ASD [21][22][23]. To maintain postoperative sagittal alignment, pelvic screw insertion, as a strong anchor of spinal fixation, became an indispensable technique not only in patients with DISH, but also in many clinical scenarios such as adult degenerative scoliosis, flat-back syndrome and kyphosis [24]. S2-Alar-Iliac (S2-AI) instrumentation has spread rapidly as a pelvic anchoring method for penetrating the SI joint.…”

Comparative tomographic study of the S2-alar-iliac screw versus the iliac screw

“…Spinopelvic rigid fixation is often necessary for the treatment of complex spinal pathologies [1]. The options described in the literature refer to the Galveston technique, developed by Allen BL, Jr., and Ferguson RL, which involves the longitudinal insertion of a bar between the two cortices of the iliac bone, or to more modern techniques, such as the use of the iliac screw (IS) and the S2-alar-iliac screw (S2AI) [2][3][4].…”

“…However, studies on the ideal technical positioning of both techniques are limited [10][11][12]. In addition, no reports have categorically determined the best positioning of the implant or performed a comparison between these techniques [1][2][3].…”

The three-dimensional printed template guided technique for S2AI screw placement and a comparison with freehand technique

“…Whether the S2AI screws can penetrate the ideal iliac plane smoothly mainly depends on the iliac width, which is described as the narrowest width of pathway within the iliar teardrop (NW). Previous studies de ned the standard S2AI screws ranges from 70 to 100 mm in length and 5.0 to 7.5 mm in diameter [17,10]. A study from Wang showed that the iliac canal width ranged from 17.4 to 32.4 mm in males and 13.5 to 20.3 mm in females in Chinese population.…”