Anatomic and Radiographic Considerations for Placement of Transiliac Screws in Lumbopelvic Fixations

Abstract

Lumbopelvic fixation in spinal and pelvic surgery relies on rods or screws as an iliac anchor. Secure placement of screws with maximum diameter and length for the greatest pullout strength requires knowledge of the iliac structure and of intraoperative fluoroscopic landmarks for secure placement. Therefore, the authors evaluated the intrailiac length, inner width, and cortical thickness of three different transiliac screw anchor paths aimed toward the anterior inferior iliac spine and initiated at the iliac tubercle, posterior superior iliac spine, or posterior inferior iliac spine. Measurements were made using two- and three-dimensional computed tomographic reformations in 40 consecutive trauma patients (27 measurements in 21 males, 16 to 75 years old; 28 measurements in 19 females, 16 to 78 years old). In addition, fresh and dry human cadaveric specimens were marked with metal wires at the previously determined optimal screw path to determine fluoroscopic landmarks for easiest and best controlled transiliac screw placement. The posterior superior iliac spine-anterior inferior iliac spine path had the largest bony canal lengths, with 141 mm in male and 129 mm in female patients. Two stereotypic iliac constrictions allowed placement of 8-mm implants in male and 6- to 7-mm implants in female patients. Cortical thickness at that optimal extraarticular path was 5.2 mm in the male and 4.7 mm in the female patients. Transiliac screws can be placed during operation under fluoroscopic control using standard lateral and obturator oblique-outlet views, the latter presenting a stereotypical teardrop figure above the acetabulum.

Biomechanical advantages of dual over single iliac screws in lumbo-iliac fixation construct

“…In this study, the superior and inferior iliac regions rich in cancellous bone were named as the upper and lower iliac columns, respectively, and were regarded as the important anchoring areas for iliac screw fixation [6,9,10]. Previous imaging and anatomical research have confirmed that the height and width of the lower column is sufficient for inserting two 8 mm diameter screws till the level of GSN [9,12].…”

“…Anatomic and radiographic studies have confirmed that there are two columns in the upper and lower areas of the ilium where the cancellous bone is found in abundance [6,[9][10][11][12]. The upper iliac column stands from the posterior superior iliac spine (PSIS) to the highest portion of the iliac crest; the lower column is located in the area from PSIS to the anterior inferior iliac spine (AIIS).…”

“…The upper iliac column stands from the posterior superior iliac spine (PSIS) to the highest portion of the iliac crest; the lower column is located in the area from PSIS to the anterior inferior iliac spine (AIIS). These two columns contain a linear bony area which can provide sufficient anchoring for the placement of iliac screws [6,[9][10][11][12]. Importantly, at the level of great sciatic notch (GSN) of the lower iliac column, there is a narrow, cortex-rich point which can provide a rigid purchase for the iliac screws [9,12].…”

Resultado a largo plazo de las fusiones largas espinopelvicas en escoliosis: importancia de la edad, la capacidad de marcha y el tipo de fijación ilíaca

“…Based on anatomical and biomechanical studies that demonstrate the existence of an extensive anatomical area of the posteroanterior iliac spine that permits solid anchoring of iliac screws 17,19,20 and of the biomechanical improvements in the use of more than one iliac screw, 19,20 it has been proposed that the use of more than one iliac screw bilaterally improves stability and the ability to correct spinal deformities. 19,21,22 In a previous study that presents incidence of implant failures similar to ours, 14 the incidence of failures of implants using one or two bilateral iliac screws for long fusions in patients with scoliosis of neurological etiology was evaluated, determining that the use of two bilateral iliac screws significantly reduced the number of instrumentation failures.…”

A novel “pelvic ring augmentation construct” for lumbo-pelvic reconstruction in tumour surgery

“…Lumbo-pelvic reconstruction is a challenging problem despite the advances in tumour reconstructive surgery [1][2][3][4][5][6][7][8]. The anatomy of this region, poor quality bone and non-availability of stable anchoring sites frequently place enormous loads at this junction [9].…”