Review Question - QID 214064

An ABI of 0.81 is abnormal and would warrant a CTA to better evaluate for vascular injury.

The location of this particular fracture is concerning for vascular injury. Patients with a lack of hard signs of vascular injury such as arterial bleeding, absent distal pulses, limb ischemia, and expanding hematoma are often evaluated with an ABI. The ABI is performed by taking the systolic blood pressure at the ankle and dividing it by the systolic pressure of the arm. ABI <0.9 are abnormal and require further evaluation with a CTA. If the ABI >0.9, there is a 100% negative predictive value of arterial injury and serial examinations should be performed.

Seamon et al performed a validation of current practices in the detection of vascular injuries with CTA. They report that the use of a CTA had 100% sensitivity and specificity for clinically relevant vascular injuries. They conclude that CTAs are rapidly available, have a favorable cost profile and should be the study of choice in patients with abnormal ABIs.

Gitajn et al review the likelihood of arterial injury following civilian ballistic injuries. They report that fractures in which the distal fracture line is within the distal third of the femur have an increased risk of arterial injury, odds ratio of 6.72. They conclude that fractures in the distal third of the femur following ballistics injury require careful evaluation for arterial injury.

Figure A is an AP radiograph of the distal femur showing a comminuted distal femur fracture with bullet fragments.

Incorrect Answers:
Answer 2-5: ABI values of 0.9 – 1.3 are considered normal and would not warrant a CTA.