An articulated, adjustable, and lockable alignment arm, and associated extensions and accessories, which are user manipulable to model the size and shape of the fractured limb of a patient in the field. The alignment arm is adjusted for proper orientation by setting it over the injury, and then locking the arm into a selected orientation which models the patient's limb around the area of the injury. Next, first and second arm extenders and protective end pads are used to expand the effective size of the alignment arm to form a custom splint structure. Lastly, the splint structure is secured to the patient's injured limb through the use of flexible cravats. The cravats are self-sterilizing, stored so that their sterility is maintained, and deployed so that only the sterile portion of the cravat comes into contact with a patient's skin.