To review, this is a 27 year-old male status post multiple gunshot wounds, one of which is to the right forearm.
Questions and Answers:
1) What is the Injury?
As you can see in the above image, this patient has suffered a nondisplaced fracture of the radial aspect of the radius, likely caused by the bullet. Although it is difficult to tell the trajectory of the bullet without paper clips placed on the skin as markers, the important arterial structures do not appear to be involved in this CT slice. If the radial or ular artery were to be involved, there would be a 50% chance of concurrent nerve involvement.
2) If this patient hadn't needed a CT to evaluate his other injuries, how else could you have assessed the structures in this limb?
Gunshot wounds to extremities can damage bony, vascular,and nervous structures. For bony evaluation, AP and lateral x-rays that include both the joint above and below the entrance and exit wounds should be obtained. A paperclip, monitor lead, or other radiographic marker should be placed at entrance and exit wounds. In terms of vascular evaluation, normal pulses have been found in 20% of cases with angiographically demonstrable lesion. Penetrating injuries to the extremity should be evaluated further using arterial pressure indices, which are 95% sensitive and 97% specific for clinically significant vascular injuries of the extremity.
Nerve evaluation should include evaluation of the sensory and motor function of the median, radial, and ulnar nerves. The median nerve provides sensation for the volar aspect of the hand from the thumb up to halfway across the ring finger and innervates thumb opposition and flexor carpi radialis as well as some finger flexion. The radial nerve provides sensation to the dorsal aspect of the wrist and hand, most prominently on the radial aspect, and innervates the extensors of the fingers and wrist. The ulnar nerve provides sensation to the volar aspect of the hand of the pinky and most ulnar half of the ring finger and innervates the abduction and adduction muscles of the fingers as well as flexor carpi ulnaris and some finger flexion.
The most specific and rapid hand evaluation would include sensation of each 3 nerve distributions as well as an "okay sign" under abductive force (median nerve), a "stop sign" under flexion force (radial nerve ), and a "peace sign" against adductive force (ulnar nerve).
In patients that have nonoperative small fractures without vascular involvement, compartment syndrome is unlikely. However patients with comminuted fractures or significant arterial injuries should be evaluated for elevated compartment pressures and placed under close observation.
3) What are the next steps in management and treatment for this injury?
This injury should be irrigated copiously and packed in the emergency department with a prescription for oral antibiotics (a 5 day course of first-generation cephalosporin). Although a gunshot wound causing a fracture is technically an "open fracture," oral antibiotics have been shown to be equal in efficacy as intravenous antibiotics and empiric administration of cefazolin is not recommended in this injury pattern.
Borman KR, Snyder WH 3rd, Weigelt JA. Civilian arterial trauma of the upper extremity. An 11 year experience in 267 patients. Am J Surg. 1984 Dec;148(6):796-9.
Dicpinigaitis PA et al. Gunshot wounds to the extremities. Bulletin NYU. 2006;64:3-4.
Knapp TP et al. Comparison of intravenous and oral antibiotic therapy in the treatment of fractures caused by low-velocity gunshots. A prospective, randomized study of infection rates. J Bone Joint Surg Am 1996;78(8):1167-1171
Lynch K, Johansen K. Can Dopper pressure measurement replace "exclusion" arteriography in the diagnosis of occult extremity arterial trauma? Ann Surg. 1991 Dec;214(6)737-41.
Tosti R, Rehman S. Surgical management principles of gunshot-related fractures. Ortho Clinic N Am 2013;44(4):529-540.