Aneurysm of the distal popliteal artery and its relationship to the arcuate popliteal ligament.

IN 1953 Gifford, Hines, and Janes' clearly demonstrated the high incidence of serious complications in patients with untreated aneurysms of the popliteal artery. They pointed out that arteriosclerosis was present in almost all the 100 popliteal aneurysms that they studied and that the aneurysms were not infrequently bilateral or multiple. Popliteal aneurysms are seen predominantly in men more than 50 years of age and are usually asymptomatic until complications occur. These may be local swelling and pain, a prominent venous pattern or edema below the knee, or ischemia with intermittent clau-dication, ischemic neuritis, ulceration, and gangrene. The complications are results of local pressure from or rupture of the aneu-rysm, thrombosis within the aneurysm, or peripheral embolization from the aneurysm. In 1916 Halsted2 and Reid3 experimentally produced circumscribed dilatation of an artery immediately distal to a partially occlud-ing band and related this phenomenon to the dilatation of the subclavian artery observed in certain cases of cervical rib. Similar post-stenotic dilatation has often been observed in other arteries. In the aorta it appears commonly distal to stenosed aortic and pulmonary valves and distal to coarctate segments. The physical phenomena that occur distal to a stenotic segment of artery were described by Holman4 in 1954 as follows: A mass of fluid ejected through a narrow and limited constriction under high velocity strikes against a more slowly moving mass of fluid distal to the stenosis, resulting, first, in the conversion of high kinetic energy into high potential energy or lateral pressure and, second, in the lateral deflection of the rapid stream and even in a complete reversal in the direction of flow, thus producing eddies of alternating high and low pressure whose repeated impacts over prolonged periods against an elastic wall are capable of inducing structural fatigue and distention of that wall, resulting eventually and inevitably in the phenomenon of poststenotic dilatation. To relate the phenomenon of post-stenotic dilatation to the pathogenesis of popliteal aneurysms, a review of the anatomy of the popliteal space is necessary (fig. 1). About two thirds of the way down the thigh, the femoral artery passes posteriorly and inferiorly through the tendinous hiatus of the adductor magnus and enters the popliteal fossa as the popliteal artery. Within the popliteal space the popliteal artery lies in loose fatty tissue and is freely mobile. According to Boyd and co-workers,5 the popli-teal artery then enters a fibrous tunnel derived from the fascia …