Bursting Fracture of Balloon-Expandable Stent and Pseudoaneurysm Formation in the Left Common Iliac Artery and Endovascular Treatment With Graft Stent

Purpose: To report successful endovascular treatment of a previously implanted balloon-expandable stent bursting fracture with concomitant large pseudoaneurysm formation in the left common iliac artery (LCIA). Case Report: A 72-year-old man had been previously treated with balloon-expandable stents for severe stenotic lesion in the LCIA and left external iliac artery. Seven years later, the patient complained pain in both lower legs and back. Angiography demonstrated a 3.5-cm-sized pseudoaneurysm in the LCIA with embedded metal fragments around the lesion. An endovascular treatment was selected using a limb extension graft for endovascular aortic aneurysm repair. The device was successfully deployed, and no endoleak was observed. At 1-month follow-up, computed tomography scan confirmed patency of the implanted stent graft devices in the LCIA and the absence of any endoleak. Conclusion: Endovascular approach using a limb extension graft stent for endovascular aortic aneurysm repair can be used for treating stent fracture-related pseudoaneurysm in the common iliac artery.

C1 Lateral Mass Displacement and Transverse Atlantal Ligament Failure in Jefferson's Fracture: A Biomechanical Study of the “Rule of Spence”

BACKGROUND Jefferson's fracture, first described in 1927, represents a bursting fracture of the C1 ring with lateral displacement of the lateral masses. It has been determined that if the total lateral mass displacement (LMD) exceeds 6.9 mm, there is high likelihood of transverse atlantal ligament (TAL) rupture, and if LMD is less than 5.7 mm TAL injury is unlikely. Several recent radiographic studies have questioned the accuracy and validity of the “rule of Spence” and it lacks biomechanical support. OBJECTIVE To determine the amount of LMD necessary for TAL failure using modern biomechanical techniques. METHODS Using a universal material testing machine, cadaveric TALs were stretched laterally until failure. A high-resolution, high-speed camera was utilized to measure the displacement of the lateral masses upon TAL failure. RESULTS Eleven cadaveric specimens were tested (n = 11). The average LMD upon TAL failure was 3.2 mm (±1.2 mm). The average force required to cause failure of the TAL was 242 N (±82 N). From our data analysis, if LMD exceeds 3.8 mm, there is high probability of TAL failure. CONCLUSION Our findings suggest that although the rule of Spence is a conceptually valid measure of TAL integrity, TAL failure occurs at a significantly lower value than previously reported (P < .001). Based on our literature review and findings, LMD is not a reliable independent indicator for TAL failure and should be used as an adjunctive tool to magnetic resonance imaging rather an absolute rule.

Posterior C1 Stabilization Using Superior Lateral Mass as an Entry Point in a Case With Vertebral Artery Anomaly: Technical Case Report

BACKGROUND AND IMPORTANCE: This is the first report of using the superior lateral mass as an alternative starting point for C1 posterior screw placement, demonstrating the importance of recognizing vertebral artery (VA) anomaly in deciding the surgical strategy for C1 screw placement. CLINICAL PRESENTATION: A 56-year-old man presented with severe neck pain after a fall. Imaging demonstrated an unstable bursting fracture at C4, C1-2 instability, and a subluxation at C2-3. Computed tomography angiography indicated that the persistent first intersegmental artery was located on the left side. The patient underwent anterior-posterior cervical fixation and fusion. Posterior C1 fixation was done with polyaxial screw rod construct using C1 superior lateral mass on the left side and C1 inferior lateral mass on the right side. The patient had no immediate postoperative deficits. At the 8-month follow-up examination, the patient was neurologically intact with a solid cervical fusion. CONCLUSION: The third segment of the VA is heterogeneous; therefore, preoperative radiologic studies should be performed to identify any anatomical variations. Using preoperative 3-dimensional computed tomography angiography, we can precisely identify an anomalous VA, thereby significantly reducing the risk of VA injury. To avoid significant morbidities associated with VA injury, a more optimal entry point for C1 fixation can be selected if a persistent first intersegmental artery or fenestrated VA is detected.