Evidence-Based Management of Wilderness Injuries

This is the next post based upon a presentation given at the Wilderness Medical Society Annual Meeting held in Snowmass, Colorado from July 24-29, 2009. The presentation was entitled “Evidence-based Management of Wilderness Trauma with Case Studies from Vermont Search & Rescue.” It was delivered by Tim Burdick, MD, who is a Fellow of the Academy of Wilderness Medicine, Assistant Professor of Family Medicine at the University of Vermont College of Medicine, Medical Officer for Stowe Mountain Rescue, and Medical Team Manager for FEMA Urban Search & Rescue Massachusetts Tasks Force 1.

There are clinical decision rules (or “tools”) used by physicians in order to control the number of tests (such as x-rays) they use to determine whether or not patients have specific injuries. The purpose of such rules is to avoid unnecessary testing, which can add to undesirable consequences, such as additional expense and radiation exposure. In the wilderness, the purpose of decision rules is to determine the likelihood of diagnosis, who might need an evacuation, and when it is advisable to continue or discontinue a trip.

Dr. Burdick noted that there are evidence-based clinical tools for ankle and midfoot fractures, cervical spine (neck) fractures, shoulder dislocations, and detection of fractures (broken bones) using a tuning fork.

The Ottawa ankle decision rules for the use of x-rays to determine the presence or absence of an ankle fracture were determined in patients who had mostly twisted their ankles, rather than fallen. According to these rules, an ankle fracture might exist if (1) the patient complains of pain near either malleolus AND (2) can’t bear weight for a distance of four steps OR suffers bony tenderness (when you press) in either malleolus. As it turns out, the test has a positive predictive value (e.g., when the test is positive the patient has a fracture) of 17% and a negative predictive value (e.g., when the test is negative the patient does not have a fracture) of virtually 100%.

There is something similar for neck fractures. For a blunt injury (e.g., not a stab wound, or “penetrating” injury), here are a set of criteria for which a patient should be evaluated:

1. Patient is alert and reliable
2. Patient is not intoxicated
3. There is no painful, distracting (from the examination) injury (such as a broken leg)
4. There is no focal abnormal neurological finding (such as weakness in the grip strength of a hand, or abnormal deep tendon reflex)
5. There is no midline cervical spine (neck) tenderness when the neck is examined

If all of these conditions were met by a good examination, then according to the medical literature, then only 2 out of 4307 persons initially complaining of neck pain turned out to have a broken neck.

What about dislocated shoulders? The usual admonition against attempting to reduce a shoulder dislocation prior to obtaining x-rays is to avoid tugging on a broken arm, in the event that a fracture-dislocation is present. It appears that there is a greater risk of fracture-dislocation if the victim’s age is less than 40 years and the mechanism involves “substantial force” (e.g., motor vehicle accident, assault, sports injury, or a fall from a distance greater than the victim’s personal height); or in a victim age 40 years or greater, if there is bruising around the humerus (long “upper” bone of the arm) or if the dislocation is the first for the victim. However, given all of this, it is still not clear that attempting the relocation of a dislocated shoulder that happens to be associated with an undetected fracture of the humerus is a big problem, unless one applies extreme force in the attempt and significantly worsens the break. Certainly, putting a shoulder back in place and allowing the victim greater mobility, reducing pain, and perhaps creating a situation that enables self-extrication can be extremely important.

Can someone use a tuning fork to diagnose a longbone fracture? The concept is that sound is conducted through intact bone and joints better than through broken bone. The technique is to place a vibrating tuning fork of a bony prominence beyond (distal to) the suspected fracture and then to listen with a stethoscope over a bony prominence in front of (proximal to) the suspected fracture. Sound conduction is compared between identical exams of the injured and contralateral (uninjured) limb. Decreased conduction (appreciation of sound transmittance) would indicate a possible fracure. One brief analysis of this concept in 1987, utilizing a 128 hertz tuning fork and stethoscope, indicated that it might be useful, improving the detection of fractures by a few percentage points.