Considering the proximity of the major vascular structures to the back of the knee, vascular complications of total knee arthroplasty are relatively rare. A patient who developed acute vascular insufficiency immediately following a total knee arthroplasty is reported. This stimulated a survey of arterial complications encountered by members of the British Association for the Surgery of the Knee. The majority of surgeons still use a tourniquet but will modify their practice if there is anxiety about vascular status. The mechanism of injury to the vascular system is either direct trauma or thrombosis. The outcome following treatment after direct injury is extremely good. The outcome after thrombosis is extremely poor. There is no recorded case of thrombosis occurring when a tourniquet was not used. Whether all knee arthroplasties should be done without a tourniquet is discussed. Early intervention is vital if a vascular injury is suspected.