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Sprained Ankle Management

Buck's first aid knowledge bank.
by Buck Tilton

Based on an informal survey of outdoor programs, ankle sprains account for approximately one out of every three backcountry injuries that require an evacuation of the patient or, at least, a shortening of the intended trip. Sprained ankles are the reason for 53 percent of all evacuations (due to injury) from National Outdoor Leadership School (NOLS) courses. Interestingly, 85 percent of all ankle sprains involve only the lateral (outside) ligaments. Many of these injuries can be managed in the field, without an evacuation.

Basic Anatomy

The lower leg's large tibia and smaller fibula meet the ankle at the talus, an upwardly rounded bone that allows the tib and fib to "rock" on its top. The talus, in turn, "rocks" on top of the calcaneous (heel bone). This ability to rock allows for freedom of movement when the human body hikes, climbs, or runs.
In front of the calcaneous lies two small bone, the navicular on the medial aspect (inside) of the foot, and the cuboid on the lateral aspect. In front of these two bones are three even-smaller bones called the cuniforms, for a total of seven "ankle bones." In front of the cuniforms are the five metatarsals (foot bones) that connect to the phalanges (toe bones).
It takes a complex arrangement of ligaments to hold all those bones together! But six of these ligaments are primary targets for injury. Two of these, the anterior (front) and posterior (rear) tibio-fibular ligaments, hold the tib and fib together, preventing those bones from being wedged apart by the talus when you take a step. Number three, the deltoid ligament, attaches the tibia to bones on the inside of the ankle. The deltoid is wide and tough, allows little eversion of the ankle (a roll to the outside), and is rarely sprained. In fact, twisting of the deltoid is more likely pull off a fragment of bone (an avulsion fracture) than to sprain the ligament. On the outside of the ankle, the other three primary ligaments attach the fibula to the talus and the calcaneous: the anterior and posterior talo-fibulars, and the calcaneo-fibular. These smaller, weaker lateral ligaments allow much more inversion than the deltoid allows eversion and, consequently, they are the ones most often damaged.

Assessment

Ankle assessment is relatively simple. Start with the basic historical questions: what happened? how far did the ankle twist? which way? was there a sound at the moment of stress on the ankle (other than a yell from the patient)?
Look at the ankle. Is there swelling? discoloration?
Feel the ankle. Is there pain when you press on location of underlying ligaments?
Move the ankle passively through it's range of motion. When you stress the ligaments, gently, do they hurt? do you hear a grinding sound?
Degree of pain and loss of range of motion are the primary indicators of ankle injury!

Management

All ankle injuries should be managed initially with adequate RICE-ing. REST the injury--get off it! ICE the injury--cool it with an ice pack, snow pack, soaking in a cold mountain stream, wrapping it in a wet T-shirt, etc. COMPRESS the injury, with an elastic wrap from distal to proximal (from the end of the extremity toward the heart). ELEVATE--prop the injury up higher than the patient's heart. Maintain RICE for 20-30 minutes, then allow the injury to rewarm naturally (12-15 minutes) before performing the assessment tests.
Monitor the ankle post-RICE for swelling and discoloration, the degree of which will help determine the extent of injury. In the end, the patient will be the best determiner of usability. Mild ankle injuries can be taped and the patient will be able to stay in the field. Moderate injuries can be taped to allow the patient to limp out of the field on their own, probably with most of the weight from their pack distributed among other group members. Ankle taping is a skill that should be mastered or, at least, semi-mastered by all wilderness medicine providers. A simple ankle taping method is explained in Medicine for the Backcountry, 2nd edition, available from the WMI Bookstore. Better yet, learn from someone who knows. Ankle taping is taught in many wild med courses, including WFR and WEMT courses taught by WMI. Severe ankle damage will require splinting and, most likely, carrying of the patient out to definitive medical care.

References

1. Chisolm, "A Backcountry Guide to Lower Extremity Athletic Injuries", NOLS, February 1986.
2. Donelan and McCaleb, "Athletic Injuries", JEMS, January 1991.
3. Gentile, Morris, Schimelpfenig, Bass, and Auerbach, "Epidemiology of Wilderness Injuries and Illnesses", NOLS, an unpublished paper, 1991.

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