Numerical Simulation of Asymmetrically Altered Growth as Initiation Mechanism of Scoliosis

The causes of idiopathic scoliosis are still uncertain; buckling is mentioned often, but never proven. The authors hypothesize another option: unilateral postponement of growth of MM Rotatores or of ligamentum flavum and intertransverse ligament. In this paper, both buckling and the two new theories of scoliotic initiation are studied using a new finite element model that simulates the mechanical behavior of the human spine. This model was validated by the stiffness data of Panjabi et al. (J. Biomech. 9:185–192, 1976). After a small correction of the prestrain of some ligaments and the MM Rotatores the model appeared to be valid. The postponement in growth was translated in the numerical model in an asymmetrical stiffness. The spine was loaded axially and the resulting deformation was analyzed for the presence of the coupling of lateral deviation and axial rotation that is characteristic for scoliosis. Only unilateral postponement of growth of ligamentum flavum and intertransverse ligament appeared to initiate scoliosis. Buckling did not initiate scoliosis

Nationwide Experience of Cardio- and Cerebrovascular Complications During Infrainguinal Endovascular Intervention for Peripheral Arterial Disease and Acute Limb Ischaemia

ObjectivesEndovascular treatment for peripheral arterial disease (PAD) is increasingly used and also continuously applied to more severe vascular pathology. Only few studies report on systemic complications during these procedures, but it is important to address these risks. We report the results of a recent national audit on cardio- and cerebrovascular complications after endovascular procedures for PAD.MethodsData from the Swedish Vascular Registry (Swedvasc) were retrieved on all infrainguinal endovascular procedures performed between May 2008 and December 2011. A total of 9187 cases were analysed regarding the prevalence of myocardial infarction and major stroke within 30 days post-intervention.A literature review in PubMed and Cochrane databases was conducted.ResultsThe risk of myocardial infarction was 0.3% in intermittent claudication, 1.2% in critical limb ischaemia and 1% in acute limb ischaemia. Corresponding risk of major stroke was 0.4%, 0.3% and 1.4%. Thrombolytic therapy was associated with a threefold risk of major stroke.Only a few studies relevant to the subject were found during the literature review.ConclusionsIn this population-based study we found a low risk of cardiac complications, but catheter-administered thrombolytic therapy entailed a non-negligible risk of major stroke