Popliteal aneurysm: morphology and management.

Since January 1988, 32 patients have presented with 44 popliteal aneurysms (22 thrombosed, 22 non-thrombosed). Patients with thrombosed aneurysms were older (median age 72 versus 66 years), and more likely to have bilateral lesions (P < 0.02) and serious associated cardiovascular disease (P < 0.02). Nineteen aneurysms thrombosed acutely; 12 were treated with intra-arterial thrombolysis, which was at least partially successful in seven. All 12 were subsequently bypassed, as were the other seven which were associated with such severe ischaemia that they required urgent operation. One patient died and two others required major amputation. Other complications included foot-drop (two patients), renal failure (one) and wound infection (two). Two grafts thrombosed and required re-exploration. Elective bypass was carried out in 11 patients without acutely thrombosed aneurysms; there were no significant postoperative problems. Distortion within the aneurysm (P < 0.01), large size (P < 0.01) and distortion of the popliteal artery above or below the lesion (P < 0.02) were all associated with thrombosis. Stenosis within the aneurysm was more likely in patients with multiple lesions (P < 0.01) and distortion with larger aneurysms (P < 0.01). After correcting for distortion, none of the other variables was independently significant. The combination of distortion and diameter > 3 cm was present in 13 of 15 thrombosed aneurysms. Morbidity is high following acute thrombosis of popliteal aneurysm. Distortion of the aneurysm appears to be a more sensitive predictor of thrombosis than size alone. The combination of distortion with a diameter > 3 cm may help to define popliteal aneurysms that should be bypassed electively.