Using guidance from an ultrasound machine, the FNB group will have 20ml of 0.5% bupivacaine (a local anesthetic of long duration) injected into the front of the thigh, at the site of pain. Patients randomized to the SC group will receive an injection of saline (saltwater) so that no neither the patient or the treating physician knows to which group the patient was randomized. All blocks will be performed in the emergency department by an emergency physician trained in the use of ultrasound and ultrasound guided nerve blocks.