Assessment and Treatment of Ankle Injuries

A few summers ago, while playing basketball at a YMCA camp in northern Wisconsin, I landed awkwardly and rolled my ankle. I had done this before, but this time I felt several pops. By the time I fell to the ground, my foot was displaced 70º to the medial side with a sub-talus dislocation. What does that mean? How is it different from a sprain or fracture?

Each step puts 1.5 times your body weight of pressure on your ankle. On average, we walk 1,000 miles per year. Ankle injuries account for over 14.2 million physician visits annually, but only 15% of these injuries are fractures. This article will:

• Discuss the anatomy and function of the ankle joint and foot
• Review kinematics and mechanisms of injury
• Show how to perform a thorough ankle examination
• Show how to apply appropriate treatments for an injured ankle.

Anatomy
Topographic anatomy is the language of orthopedics, using the following terms to locate a body structure relative to another structure: proximal--closer to the body's core; distal--further from the core; medial--toward the center of the body; lateral--toward the side or edge; superior--top of the foot; inferior--toward the bottom; anterior and posterior--front and back.

Understanding these terms can help us locate anatomical structures and communicate the location of injuries.

The ankle joint and foot are composed of 26 bones.¹ The ankle joint starts at the distal end of the tibia and fibula. The fibula is on the lateral side of the ankle, the tibia on the medial. The distal ends of the tibia and fibula comprise the medial and lateral malleolus--or the bony prominences you can palpate. Below the malleolus are the tarsals, a group of seven bones. The talus, or ankle bone, is distal to the tibia and fibula and is the most important tarsal bone. Its odd shape is key to the ankle's range of motion and its positioning is crucial.

The calcaneus, or heel bone, is inferior and posterior to the talus. Anterior to the calcaneus are the navicular and cuboid bones. The last three tarsal bones are the cuneiform bones. Five metatarsal bones are numbered 1 through 5 medial to lateral; there are 13 phalanges in the digits of the foot.

Numerous tendons control foot and ankle movement. Tendons connect muscles to bones. Five tendons connect to the calf muscle and control movement in all directions. The Achilles tendon is the largest tendon in the ankle and connects the calcaneus bone to the calf muscle. The tendon of peroneus longus connects at the base of the fifth metatarsal and the peroneus brevis at the first. Both wrap posteriorly around the medial malleolus. The tibialis anterior connects with the cuneiform bones and runs along the anterior surface of the ankle to the calf. The hallicus longus tendon wraps on the posterior aspect of the lateral malleolus to the navicular bone.

One hundred and nine ligaments provide the integrity and strength of the ankle and foot's structure; again, five are most important. The names describe which bones the ligaments connect. The tibiofibular connects the distal ends of the tibia and fibula. The posterior talofibular ligament connects the talus and fibula. The calcaneofibular connects the calcaneus and fibula. Off of the tibia are the tibiocalcaneal and posterior tibiotalar ligaments. Tenderness or instability are indications of a ligament tear.

The location of major arteries in the ankle is important for accurately assessing circulation after an injury. Major nerves innervating the foot follow an artery. There are two arteries in the ankle that prehospital personnel must be able to locate: The dorsalis pedis artery extends from the anterior tibial artery across the top of the ankle onto the dorsum of the foot; the deep peroneal nerve lies on the lateral side of the artery.

The other artery is the posterior tibial artery. This artery runs down the posterior tibia and around the medial malleolus and is best felt on the inferior aspect of the medial malleolus.