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A brief background of combat injuries

By Peter Pollack and Carolyn Rogers

Given the current tensions in the Middle East, treatment of combat injuries has become an increasingly important aspect of orthopaedic surgery—a fact reflected in the programming for the 2007 AAOS Annual Meeting, which featured two symposia and a media briefing addressing the topic.

Both military and civilian personnel participated in the sessions. Among the speakers were Capt. Dana C. Covey, MD; Roy K. Aaron, MD; Lt.Col. Romney Anderson, MD; Jason H. Calhoun, MD; Thomas A. Einhorn, MD; Lt. Cmdr. H. Michael Frisch, MD; Col. James R. Ficke, MD; Col. Roman Hayda, MD, MC; L. Scott Levin, MD, FACS; Cmdr. Michael T. Mazurek, MD; Col. Elisha T. Powell IV, MD; Maj. David Rozelle, Edward Schwarz, PhD; and Joseph C. Wenke, PhD.

Advances in medical care and improvements in both body and vehicle armor have combined to increase a wounded soldier’s odds of survival, which have risen from 76.4 percent during the Vietnam War to 90.4 percent in Iraq. Yet this survival rate comes at a price. Many survivors have sustained traumatic orthopaedic injuries: approximately 70 percent of war wounds are musculoskeletal injuries, and 55 percent are extremity wounds. Fractures account for 26 percent of combat injuries, and 82 percent of all fractures are open fractures.

A different type of injury
Although much of the knowledge gained through civilian orthopaedics can be applied to combat situations, much of it cannot. Combat injuries often involve high-velocity shells, which are likely to result in injuries that are very different from those seen in civilian trauma centers, which are due to lower velocity bullets. Additionally, injuries from explosives are much more common.

“Blast wounds and high-velocity missile wounds are very complex,” explained Col. Hayda, who pointed out that civilian physicians need to be aware of these issues, particularly in the event of a terrorist attack. Because they are cheap, relatively easy to make, and have a devastating effect, explosives are attractive weapons for terrorists; about 80 percent of injuries from terrorist attacks are due to explosive blasts.

In battlefield injuries, tissue loss and a high degree of contamination are extremely common. Contamination and soft-tissue injuries caused by improvised explosive devices (IEDs) require a more aggressive treatment approach than most gunshot wounds do. Regardless of magnitude, explosive injuries—which result in a much greater loss of muscle and bone—are qualitatively different from gunshot wounds.

The fact that these injuries are sustained in an austere and dangerous environment, with limited treatment resources available, only adds to the challenge. Modern injuries are successfully treated using a specific protocol of treatments that ranges from surgical débridement and leaving all wounds open to early fracture stabilization, administration of broad-spectrum antibiotics, and rapid evacuation to higher levels of care.

BALAD, Iraq – U.S. Air Force Col. Elisha Powell, commander, 332nd Expeditionary Medical Group theater hospital, and Col. Jack Ingari operate on a 101st Airborne Division Soldier after an IED attack Dec. 3. Both are orthopedic surgeons at the hospital at Balad Air Base, which treats approximately 400 patients per month —both U.S. and Iraqi forces, as well as local nationals. (U.S. Army photo by Sgt. Dallas Walker)

The physics of an explosion
In an explosion, air pressure rises precipitously outward in a shock wave because of the rapid conver sion of liquids and/or solids into gas. As the shock wave passes, the pressure quickly drops to less than normal, then rises and stabilizes again. The period of low pressure results in a reverse “wind” that can suck debris backward into the blast area, resulting in additional injury.

According to Dr. Hayda, in an open air blast, the force of an explosion dissipates very quickly on a geometric scale, concentrating the most serious effects nearest the center of the explosion. In comparison, a blast in an enclosed space such as a building will result in resonating shock waves that can complicate both injury and triage. Lower-energy explosions tend to result in more debris damage, while higher-energy explosions are likely to result in greater initial shock damage. Due to the complex series of factors that may play out in an explosion, orthopaedists who treat such injuries must exercise care and not take them at face value.

Blast injuries can be categorized into four levels. The primary blast injury is caused by stress, shock, and shear waves. At this level, any air-bearing organs such as lungs or the colon can be compressed quickly, resulting in severe tissue damage. Primary blast injuries can also result in traumatic amputation.

Secondary blast injuries are due to debris moving through the area of the blast. Tertiary blast injury is caused when a person is thrown into something such as a wall. Finally, quaternary blast injuries consist of multidimensional injuries caused by other factors related to the blast, such as burns from a resulting fireball.

Combat injury issues through the years
According to Dr. Calhoun, amputation was a primary means of controlling infection during the U.S. Civil War because antiseptic techniques of the era were crude or nonexistent. Gangrene was a common complication, and many soldiers didn’t survive an amputation.

In World War I, delayed primary closure had replaced amputation in many cases, and mortality rates from extremity wounds decreased, even though the battlegrounds in that war were breeding grounds for infection.

By World War II, surgical débridement had become more common, and large-scale production of penicillin reduced mortality rates further. Still, many physicians considered amputation to be a first-choice alternative to infection, and stories abounded of injured soldiers being quietly advised by their nurses to “ask for the shot” [of penicillin] when presented with a choice of infection treatment options.

During the conflicts in Korea and Vietnam, soldiers could be more easily evacuated to more capable and sanitary facilities far behind the battlefield, a trend that continues today. A soldier who sustains a severe injury in Afghanistan or Iraq could be in a hospital in the San Antonio (Texas) Military Medical Center within 48 hours, according to Dr. Hayda.

Airman 1st Class Louis P. Grassi (front left), Maj. Armando L. Rosales (rear left), Tech. Sgt. Ronald Whitman (front right) and Tech. Sgt. Michael Zimmer (rear right)—all of the 506th Expeditionary Medical Squadron—transfer an injured Soldier from an Army medical evacuation helicopter for surgical stabilization.

Infection remains a factor
Yet even with advances in transportation and sanitation, infection remains a primary issue. Dr. Calhoun recommended that surgical antimicrobial prophylaxis be initiated just before an operation begins and continued for no longer than 24 hours. He pointed out that multidrug-resistant organisms are cause for concern, as is Acinetobacter baumannii, although the latter may be more of a marker than an issue of its own.

In the future, Dr. Calhoun would like to see more studies done on the choice and timing of introducing antibiotic agents in battlefield injuries. He opined that clinical research on combat wounds may show that antibiotics introduced at the time of injury (incision) are effective and predicted that more work will be done in the area of genetics, which will help physicians to identify and treat resistant strains of bacteria.

Despite all of the advances in medical technology, soldiers continue to return from the battlefield with injuries that cannot be adequately repaired. Still, the state of the art continues to improve, and there is a strong bond between orthopaedic surgeons working with combat-wounded individuals and those in civilian environments.

Combat conditions rarely lend themselves to clinical study, so despite the difference between the types of trauma commonly encountered, research being done in civilian fields is often carried over into the military. Much as the space program has contributed technology to the lives of those on earth, the extreme environments of the battlefield contribute to the field of orthopaedics in a way that clinical studies cannot. Although war is an unfortunate truth of modern life, both civilian and military orthopaedic surgeons are working hard to take the lessons learned and turn them into a better future.

Mar/Apr 2007 AAOS Now
http://www.aaos.org/news/bulletin/marapr07/research2.asp