Journal of Invasive Cardiology

EDITOR’S NOTE: This article by Diaz et al. contains extremely valuable information. The importance of assessing the “dynamic anatomy” of the popliteal artery (and other vessels) was only recently appreciated as a result of developments with endovascular therapy and the increasing use of fracture-prone intraluminal metallic stents. The findings described by the Argentinian group should prove useful to interventionists who are planning to perform a stenting procedure in a given patient. But even more so, they will likely have an impact on current R&D efforts and concepts surrounding stent technology for treatment of infra-inguinal disease — a very significant area in interventional medicine indeed! — Frank J. Criado, MD, Director, Center for Vascular Intervention, Chief, Division of Vascular Surgery, Union Memorial Hospital/MedStar Health, Baltimore, Maryland.

Stenting of the popliteal artery (PA) is a therapeutic option for several diseases affecting this artery, including atherosclerosis, aneurysm, and injury with pseudoaneurysm and/or arteriovenous fistulae formation.^1–6 Because the PA is exposed to movements of the knee joint, self-expandable stents and endovascular stent grafts are commonly used owing to their crush-reversible properties. This condition is advantageous in areas where the body is exposed to external force or movements.⁷ However, fractures of self-expandable stents have been reported, including those used in the PA.^8,9 Vessel compression and movement are thought to promote development of hinge points (HPs), which ultimately lead to stent fractures.⁹ However, it is still not completely clear where HPs occur in the PA.
The purpose of the present retrospective study was to describe the morphologic changes of the PA during knee flexion and their relationship with bone structures using dynamic angiography (DA).

Patients and Methods
In February 2000, a patient who had a stent implanted in her right PA underwent angiography at our institution. Because the patient was unable to extend her right knee due to severe pain, angiography was performed with the knee bent at 100º. Arterial blood flow was severely decreased in the distal end of the stent. The low-flow segment was coincident with the presence of an HP of the PA (Figure 1).
This observation led us to routinely perform conventional angiography (CA) (with the knee in extension) followed by a DA (with the knee in flexion), as an attempt to identify the exact place where the PA has an HP during knee flexion in those patients requiring a therapeutic procedure involving the PA.
Patients. Adult patients who had been referred to our department by their primary physician for angiography of the lower extremities to diagnose arterial disease were included. Only symptomatic legs were studied. DA was not performed in patients with renal failure (serum creatinine >= 1.40 mg/dL), history of allergy or intolerance to the contrast material injected during CA, and/or a segment of the PA that was not visible during CA.