The Etiology of Injuries in US Army Initial Entry Training.

Background: US Army initial entry training (IET) trainees engage in intense physical activities for 10 or more weeks prior to their assignment to operational units. Many trainees succumb to injury during IET. Injuries to the lower extremities and back have historically been the most common, and thus have been the focus of routine health surveillance.

Objectives: The primary goal of this analysis was to verify the training-related injuries of greatest concern and to update the clinical diagnostic codes (ICD-10-CM) used in surveillance. The investigation also aimed to develop a sense of the financial magnitude of these injuries.

Methods: The distribution of all IET injuries was determined using a comprehensive injury taxonomy. Injuries were categorized based on causal energy source (mechanical, thermal, radiant, nuclear, chemical, or electrical). Mechanical energy transfers included acute trauma and cumulative microtrauma ("overuse"). Injury ICD-10-CM codes were identified in calendar year 2016 IET trainees' electronic healthcare records. Injury frequencies were reported for gender, body region, and injury type. Costs were calculated from medical encounters and estimated lost training time using the most frequently injured anatomical site as a baseline.

Results: Among 106,367 trainees, 65,026 separate injuries were identified. Mechanical energy transfers to lower extremities caused 75% of all injuries; most (65%) were cumulative microtraumatic. The most frequently injured anatomical site (the knee, 20% of injuries), is estimated to have cost over $39 million.

Conclusions: Lower extremity injuries, followed by those of the low back continue to be leading "training-related injuries". This suggests the need to ensure distances and/or frequencies of weight-bearing activities (running, foot-marching) are not increased too rapidly or too excessively, and that trainees' fitness prior to IET is adequate. Medical costs and lost training time should be included in future monitoring.