Foot News

Ankle sprains and stategies to prevent them
September 5, 2011

This article:

  • Explains the mechanism of ankle sprains.
  • Discusses strategies to prevent them.
  • Discusses treatment of ankle sprains.

Ankle sprains are an unfortunate and common injury in sports including basketball, soccer, and football. Often ankle sprains heal without a great deal of treatment, but at times, they can take a long time to finally resolve. So what are ankle sprains, why do they occur, and what can you do about them?

An ankle sprain is a tearing of the ligaments that support the outside of the ankle. These ligaments guide the ankle through its motion, ensuring that the joint surfaces do not rock into an abnormal position so that they do not become damaged. When the ankle ligaments tear, there is bleeding, which leaks into the skin usually causing bruising along the heel, back of the calf, and top of the foot. In addition to the torn ligaments, the joints themselves get knocked around and bruised also. The joints can even chip.

The ligaments tear because they are pulled apart. One way that the ankle ligaments tears is that the body weight is applied to the leg while the foot is out of position. Another way is that weight is suddenly shifted to the outside of the ankle while the foot is planted, such as when you cut sharply while running.

Things that might predispose you to an ankle sprain could be the shape of the foot and leg, the strength of the muscles and the tightness of the ligaments. Muscle strength can be improved by conditioning exercises, especially exercises that emphasize control of the ankle and improve the flexibility and coordination of the foot.  A therapist or trainer can help you with this type of rehabilitation. There is little that can be done about the tightness of the ligaments or the shape of your foot short of surgery, so we will not discuss that in this article. One important part of ankle sprains that can be adjusted is the stability of the ankle with the shoe, which may be one of the critical mechanisms causing ankle sprains.

As anyone who has ever tried to walk on a pogo stick or stilts knows, one of the keys to mastering these skills is to keep the foot and the stick in close contact at all times. Once they come apart, you’re done. It’s the same with shoes during sports. If there is a lot of motion between the shoe and the foot, you’re going to have trouble.
ankle sprains

To illustrate this better, let’s break down an ankle sprain step-by-step (Figure A). The ankle allows the foot to move from flexion to extension. The subtalar joint motion allows side-to-side motion or technically inversion (tilting the heel toward the midline) or eversion (tilting the heel away from the midline). The ligaments on the sides of the joint control this motion and act as tethers on the joint and keep the surfaces of the joint in close contact.

The average direction of the body weight on the ankle can be approximated by an arrow, the axis of body weight. The axis of body weight in normal standing or walking, more or less, goes from the hip joint to the heel and center of the forefoot. When the axis lies between the inner and outer ligaments, there is very little tension on the ankle ligaments. If the axis of body weight begins to creep to the outside of the ankle, tension on the ligaments occurs. If enough tension builds up, the ligaments tear.

B. If an uneven surface is encountered, the heel and forefoot will tilt to accommodate it. However, if the shoe is not securely applied to the foot, the foot will slide toward the outside of the shoe.
C. As the outside border of the foot drops over the edge of the sole of the shoe, it begins to twist the foot even more. Inverting the subtalar joint as far as it will go and stretching the lateral ankle ligaments.
D. The foot then begins to roll off of the obstruction, and will continue to invert until the ankle or side of the foot hits the ground, tearing the ligaments.

What strategies can we use to avoid this? The traditional sport shoe attempts to stabilize the shoe by applying stiff (usually artificial leather) cups or reinforcements to the heel and outer border of the forefoot, keeping the foot from sliding off of the sole of the shoe. With continued use of the shoe, these reinforcements soften, so replacing the shoes can be helpful. A high top can increase the stability of the shoe by extending the upper onto the ankle increasing the leverage on the foot, reinforcing the lateral ligaments. An ankle brace similarly reinforces the ankle but can actually increase the instability of the shoe-foot connection. This is especially true when the shoe does not fit well over the brace.

Ektio, a newer shoe company, has developed a line of shoes engineered toward improving the stability of the foot and shoe. First, it has fasteners, which secure the shoe to the foot. Second, they have reinforced the stiffness of the upper along the lateral heel and forefoot to resist shifting of the foot. Third, the shoe has slight bumpers along the lateral heel and forefoot to resist rotation of the shoe. Consumer reviews are very positive for the shoe and it may help many to decrease their reliance on ankle braces for certain sports.

Barefoot or minimalist shoes over the last few years has become very popular especially among distance runners. Running while barefoot or wearing minimalist shoes increases feedback from the foot about the ground conditions. The decreased stiffness of the sole of the shoe allows the foot to adjust to changes in the contour of the ground.  This challenge also helps to condition the small muscles within the foot, which may improve stability over the long run. Running barefoot or in minimalist shoes decreases the motion between the foot and the shoe and this should improve ankle stability. There is also very little in the way of a sole, therefore, there is no elevated sole to role over. The disadvantage of barefoot running is the lack of protection of the foot from concentrations of stress and from damaging objects on the ground.  Any new shoe especially a minimalist shoe should be broken in.  More accurately, the foot needs time to adjust to the new stresses that minimalist shoewear presents to the foot to prevent overuse injuries.

There are many methods of approaching ankle sprain protection. The right one is the one that works for you. Discuss this with your physician, therapist, trainer or coach. Much of shoe wear selection is dependant on the needs of the sport. A heavier shoe may be necessary for a sport in which you can expect some contact with the other players. Experiment with it and decide for yourself what works best for you.

-Brett Fink, MD, Indiana Orthopedic Center, Indianapolis, IN, (317) 588-2663, co-author of The Whole Foot Book, A Complete Program for Taking Care of Your Feet.