ABSTRACT
In aortoiliac occlusive disease, atherosclerotic plaques can occlude the distal aortic bifurcation and proximal bilateral iliac artery and thus cause ischemia in the lower extremity. This is typically treated by restoring patency with balloon expandable stents. Stents are typically deployed in a "kissing stent" configuration into the bilateral iliac arteries and into the distal aortic bifurcation lumen to restore antegrade arterial flow. However, these stents typically become re-occluded by plaques. To understand the reasons for this and look for solutions, we simulated flow dynamics in the aortic bifurcation in the presence and absence of stents using computational fluid dynamics. Results demonstrated that the kissing stent configuration was associated with high levels of vorticity and flow constriction. These prothrombotic variables were alleviated in an alternative, aortoiliac fenestrated (AIFEN), tapered, and balloon-expandable stent design. Our findings suggest that stent design can be tailored to improve flow fields for aortoiliac stenting.
ABSTRACT
BACKGROUND: Adjacent-level disease after anterior cervical discectomy and fusion (ACDF) occurs in a significant proportion of patients and frequently requires revision operation. Methods using traditional plates typically require removal of the plate with anecdotally increased operative-time and morbidity. We review our experience in treating symptomatic adjacent-segment disease using both traditional plate removal and modular-plate system which allows for add-on plate components rather than removal of the entire plate. METHODS: Authors compared 64 patients with revision surgery using modular-plate system for adjacent-segment disease compared to 2-cohorts: 1) patients with traditional plate-removal; and 2) patients with no prior plate. Clinical data included demographics, original surgery, presentation, current surgery, use of modular system, need for preoperative computed-topography, operative-time, blood loss, hospital stay, complications, length of dysphagia, neck disability index and time-until-fusion. RESULTS: Modular cervical plate system was utilized to prevent exposure and removal of the entire plate. The terminal portion of the plate was exposed and the distal module was removed. Following the discectomy/arthrodesis, a module-plate extension was added onto the previous plate for extension of the prior instrumentation. Preoperative planning computed-topography was required in 26% of plate-removal and 17% of modular-plate cases. Revision surgery with no prior plate had reduced operative-time (77.0±18.1 min) when compared with plate removal (103.8±46.2 min; P<0.01). Blood-loss was lower for modular-plate system (38.3±20.4 mL) and no prior plate (38.4±12.6 mL) versus plate removal (78.2±65.9 mL, P<0.01). Hospital stay was similar for all groups. No complications were experienced with modular-plate revision but plate removal and revision after no prior plate carried 7.7% and 10.5% complication rates, respectively. There was a trend towards lower dysphagia and neck disability index with modular-plate revision. CONCLUSIONS: Use of modular cervical plate system allows for extension of a plate and reduces morbidity when treating adjacent-segment disease.
