ABSTRACT
We combine experiments and theory to study the mechanics of overhand knots in slender elastic rods under tension. The equilibrium shape of the knot is governed by an interplay between topology, friction, and bending. We use precision model experiments to quantify the dependence of the mechanical response of the knot as a function of the geometry of the self-contacting region, and for different topologies as measured by their crossing number. An analytical model based on the nonlinear theory of thin elastic rods is then developed to describe how the physical and topological parameters of the knot set the tensile force required for equilibrium. Excellent agreement is found between theory and experiments for overhand knots over a wide range of crossing numbers.
ABSTRACT
PURPOSE: To present the management of a spontaneous pseudo-aneurysm of the deep femoral artery by an endovascular technique. CASE REPORT: An 82-year-old man presented with a painless pulsating mass at the level of the upper right thigh without any previous history of trauma, surgery or puncture of the femoral artery. The mass proved to be a pseudo-aneurysm of the deep femoral artery. Thrombin injection with simultaneous balloon inflation at the neck of the aneurysm did not result in a long-lasting thrombosis. Since both general and epidural anaesthesia were absolutely contra-indicated, and because of severe stenotic lesions of the femoro-popliteal axis, we chose to exclude this aneurysm under local anaesthesia with a balloon-expandable covered Jo-stent in order to maintain patency of the deep femoral artery. Twenty months postoperatively, the aneurysm is still thrombosed while the patency of both the superficial and deep femoral artery is preserved. CONCLUSIONS: This case demonstrates that an endovascular approach can be an excellent treatment for aneurysms of the deep femoral artery, thereby avoiding an open surgical procedure while preserving the patency of the deep femoral artery.
