Aplastic Posterior Tibial Artery in the Presence of Trimalleolar Ankle Fracture Dislocation Resulting in Below-the-Knee Amputation.

We present an interesting, but unfortunate, case of an 86-year-old female who sustained a trimalleolar ankle fracture dislocation that resulted in below-the-knee amputation after open reduction and internal fixation of the fracture. To the best of our knowledge, this is the first case report describing popliteal variants that ultimately resulted in critical limb ischemia and below-the-knee amputation after foot and ankle trauma. The anatomic variation altered the expected outcome from a relatively straightforward surgical case. We introduce the previously described lower extremity Allen test and describe how it can be a useful adjunct in the initial physical examination of lower extremity trauma. The ability to identify abnormal distal perfusion to the foot could provide enough insight to warrant evaluating the patient with angiography or computed tomography angiography.