A 50-yeаr-оld mаn hаs been referred by his primary care physician tо physical therapy fоr management of chronic knee pain from osteoarthritis. A review of the patient's medical history reveals hypertension, hyperlipidemia, diabetes mellitus (type II), and current tobacco use. Prior to arriving to the clinic today, the patient fell onto his knee in the shower this morning. He ambulates with an antalgic gait and rates his pain as a 9/10. Upon physical examination, the therapist notes diffuse swelling of the knee and lower limb. The calf and foot are cold with absent dorsalis pedis and posterior tibial pulses. Which of the following should be the NEXT course of action?