Unintentional and Musculoskeletal Injuries: Greatest Health Threat to Military Personnel

A study of injury hospitalizations in the military has shown that although injuries declined considerably from 1980 to 1994 in all three branches of the service, injuries and musculoskeletal conditions still adversely affected the health of service members and troop readiness more than any other single diagnosis. The report particularly recommended the military use its hospital databases to conduct injury surveillance, research, and prevention, particularly the prevention of sports injuries and falls, which are both major causes of reduced troop readiness. The study, along with five other reports on injuries in the military by researchers at the Johns Hopkins School of Public Health and their colleagues, appeared in a special injury supplement in the April 2000 issue of the American Journal of Preventive Medicine.

Since 1989 the key medical database elements have been standardized among all three services, and each military hospital discharge report includes a unique personal identifier number, which allows researchers to measure the true incidence of injuries. Since up to 20 percent of injury admissions to hospitals in the civilian world may be repeat admissions for the same problem, civilian databases not using a unique identifier for each patient cannot supply reliable information on injury incidence.

The study found that the major causes of hospitalization included injuries from sports, motor vehicle crashes, falls, and jumps but that, among all groups of disorders, musculoskeletal conditions resulted in more soldiers missing time from work than any other health condition. In the Army, for instance, the combined categories of injuries and musculoskeletal disorders accounted for slightly more than 30 percent of all hospitalizations in 1992.

The report was based on work initially conducted from 1994 to 1996 as part of the activities of the Armed Forces Epidemiological Board (AFEB) Injury Prevention and Control Work Group, which was to determine the magnitude of the problem of injuries in the military. In addition to analyzing injury data, the AFEB work group evaluated the strengths and weaknesses of the hospital databases used by each service branch and made recommendations as to how the databases could be better used to reduce the burden of injuries to the military.

"Military hospital discharge databases provide tremendous potential for injury surveillance in addition to surveillance for other medical problems," said lead author Gordon Smith, MD, MPH, associate professor, Health Policy and Management, the Johns Hopkins School of Public Health, "but to date, the full potential of the data for injury prevention has only recently been recognized."

In 1992 (used as the base year for analysis since, at the time of the work group meetings, data for 1992 were the most recent data available), the 17,718 injury hospitalizations in all three services accounted for 10.9, 11.6, and 7.9 percent of all hospitalizations in the Army, Navy, and Air Force, respectively. The leading cause of hospitalization in the Army in 1992 was musculoskeletal conditions; while in the Navy mental disorders had the highest rate, with musculoskeletal conditions second; and in the Air Force digestive conditions were the leading cause of hospitalization. Hospitalizations for musculoskeletal conditions accounted for 12.3 to 19.7 percent of all hospitalizations in the three services in 1992.

The ten leading types of injury for the Army -- which accounted for 41 percent of all injury hospitalizations -- included ankle fractures, intracranial injury, fracture of face bones, sprains and strains of the knee, dislocation of the knee, fracture of radius/ulna, fracture of one or more fingers, and open wounds of fingers.

For available years, hospitalizations for injuries in all three services were more common among males than females, while hospitalizations for musculoskeletal conditions were more common among females. Among Army personnel, men were more frequently hospitalized than women for athletic injuries and for fighting; women more frequently for complications of medical or surgical procedures and for ingesting poisons. Overall, for acute injuries and musculoskeletal conditions combined, rates were higher in women in all three services.

Overall, injuries were the third leading cause of hospitalization in the Army and Air Force and also the third leading cause in the Navy if pregnancy-related conditions were excluded. Hospitalization rates for injury apparently declined for all services from 1980 to 1992. In 1992, injury hospitalization rates per 1000 person-years were 15.6 for the Army, 8.3 for the Navy, and 7.7 for the Air Force. From 1981 to 1992 (years for which data for all services was available), injury hospitalization rates decreased 38 percent in the Army, 62 percent in the Navy, and 56 percent in the Air Force. These differences between the services have continued, for reasons that are still being studied.

Reported rates of hospitalization for injuries and musculoskeletal and connective tissue disorder were also substantially higher in the Army than in the other two services, but whether because of differences in risk exposure or discrepancies in reporting cases was not determined. In any case, musculoskeletal conditions accounted for more time off from work than any other group of disorders and, in contrast to the declining trends for injuries, rates for musculoskeletal conditions in the Army increased 75 percent from 1980 to 1992, while declining 32 percent in the Navy and 20 percent in the Air Force. The researchers said more work is ongoing to determine the reasons why musculoskeletal conditions are increasing only in the Army.

Most of the 18,050 hospitalizations for musculoskeletal conditions among Army personnel in 1992 were due to recurrent or chronic effects of injuries, such as lumbar and intervertebral disc disorders and internal knee derangement. Internal derangement of the knee was the leading cause of hospitalization in this group for the Army.

The researchers cautioned that although comparisons of injury rates among the different services may identify significant differences in injury risk and suggest new prevention strategies, there are important differences in exposure to various risks among the services, as well as variations in policies and reporting practices.

Among other recommendations, the scientists urged studies of why rates of musculoskeletal conditions have increased significantly in the Army, of the factors that account for the declining rates of hospitalized injuries in all three services (are more injuries being treated in outpatient clinics?), and of family violence and workplace violence. "If previous research in the civilian world is to be used as an example, we can expect major reductions in injuries and significant improvements in troop readiness both in peacetime and combat situations."

Support for this study was provided by grants from the Centers for Disease Control and Prevention, the U.S. Army Medical Research and Materiel Command, the National Institute of Alcohol Abuse and Alcoholism, and the University of Auckland Injury Prevention Research Center.

The same April 2000 issue of the American Journal of Preventive Medicine also contains five other related articles on injuries in the military by researchers from the Johns Hopkins School of Public Health and colleagues:

• Sports and Physical Training Injury Hospitalizations in the Army. T.D. Lauder et al.
• The Use of Existing Military Administrative and Health Databases for Injury Surveillance and Research. Andrew E. Lincoln et al.
• Viewpoint: A Comparison of Cause-of-Injury Coding in U.S. Military and Civilian Hospitals. Paul J. Amoroso et al.
• Self-Reported Risk-Taking Behaviors and Hospitalization for Motor Vehicle Injury Among Active Duty Army Personnel. Nicole S. Bell et al.
• Quantitative Assessment of Cause-of-Injury Coding in U.S. Military Hospitals: NATO Standardization Agreement (STANAG) 2050. Paul J. Amoroso et al.