Prospective and retrospective analyses of 1,182 consecutive patients undergoing primary total knee arthroplasty (TKA) were performed to determine (1) the incidence of chronic lower extremity ischemia (CLEI); (2) the effect of tourniquet occlusion; and (3) guidelines that will allow TKA to be performed safely. Despite the appropriately advanced age of our patients, the incidence of CLEI was only 2%. All ischemic complications occurred in six patients with CLEI (25%), but none resulted in death or amputation. The ischemic complications consisted of pressure-induced necrosis of toes, heel, or foot, atheroembolism, femoral-popliteal graft occlusion, and asymptomatic popliteal occlusion. Tourniquet compression in the 1,158 patients without CLEI produced no untoward effects. Patients with mild CLEI can have a TKA performed safely with a tourniquet if there is no femoropopliteal calcification. When the ischemia is severe or there is a femoropopliteal aneurysm, arterial reconstruction should precede the TKA. In patients with patent femoral-popliteal bypasses or calcification without ischemia, TKA should be performed without a tourniquet. Ischemic pressure necrosis is an additional mechanism of injury.