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EMS loves mechanism of injury. The excitement of pulling up to a big crash, examining the forces that cause injuries other crews wish they responded to. Yes, we love mechanism of injury.

There is one pesky problem with mechanism of injury: It isn’t that reliable.

Mechanism of Injury vs. Actual Injury

There doesn’t seem to be any proven link between mechanism of injury and actual injury. This is exacerbated by vehicles’ safety features today and the stories of people who have walked away from seemingly unsurvivable mechanisms.

Educator and author Joe Mistovich tells a story of coming into the emergency department with a patient from a crash with a “significant” mechanism of injury. He showed the doc dramatic images from the scene. The doc was unimpressed. His response, “Everything I need to know about the crash I can find out from the patient.”

The CDC’s Trauma Triage Guidelines support this approach. The guidelines list mechanism of injury as a distant third in criteria after physiologic signs and anatomic signs (injuries). A significant mechanism of injury doesn’t even get the patient a ride directly to the trauma center.

Using Mechanism of Injury in Trauma Assessment

Click to view full flowchart.

So what does mechanism of injury tell us? We created a video and handout to help you put it all together. While mechanism doesn’t reliably predict injury, it does serve as the foundation for a few early and critical decisions. Specifically:

1. Should I expect one injury or multiple trauma?
If multiple trauma, how much do I need to look for hidden injuries?

2. What is the potential for severity?
How fast do I need to assess/get off the scene?

3. Are there spinal concerns?
Do I need to stabilize the c-spine now and (eventually) assess the spine for spinal motion restriction?

Download MOI Flowchart


In the video, there are two examples of how to apply mechanism findings in different trauma calls:

  • A 45 year old male misstepped and twisted his ankle on the curb.
  • A man shot in a bar fight is screaming about pain and holding his thigh.

We hope you find the mechanism of injury flowchart and video useful. What’s been your experience with this in the field? How has looking at mechanism of injury helped your patient assessment or led it off course? Tell us in the comments!

Mechanism of injury is only one part of patient assessment.  Check out our patient assessment guide for the overall assessment process.

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