Ankle sprains are simple injuries that can cause amazingly complex damage.  The ankle joint itself has an up and down motion.  There are ligaments (strong rubbery bands of tissue) on either side of the ankle, holding it in place.  These ligaments resist the ankle’s ability to roll inward or outward.  The foot can roll inward and outward due to the natural motion of a joint directly below the ankle joint called the subtalar joint.  However, the ankle will generally stay in place except to move the foot up or down.  When someone forcibly turns the foot inward or outward, such as when stepping in a hole, off a curb, or during strenuous activity like playing basketball, the ligaments around the ankle will become stretched.  Fortunately, there is a lot of elasticity to these ligaments, and a certain amount of ‘give’ is allowed by the body.  However, if the force on the ankle is strong enough, the ligaments will not be able to resist that strain, and will begin to tear.  If a significant amount of force is applied, or if the ankle ligaments are already weakened from a previous sprain, then the ligament will tear completely.  In the worst cases, the injury force is strong enough to fracture the ankle bones around the ligament.

Most people roll their ankle inward during a sprain, injuring the outside of the ankle.  This is mainly due to the fact that the ligament on the inside of the ankle is very strong, and rarely tears.  On the outside of the ankle there are three ligament bands.  One is in front, one is along the outside, and one is along the back of the outside of the ankle.  The front and side ligament band are most commonly injured, although the back band can be harmed in more severe sprains.  Each of these bands attaches one of the ankle bones to a bone in the foot.  A sprain will cause the band to tear to some degree, and if severe enough the tear will take part of the bone the ligament is attached to (a so-called avulsion fracture).  Over time (or immediately if the sprain is severe enough), the ankle weakens as a result of ligaments that are not as strong as before the injury.  Minor sprains will result in weakness and pain to the ankle, with a slow recovery period of 2-4 weeks.  Moderate sprains that involve several of the ligament bands take longer to heal and may be more painful.  Serious sprains and fractures take months to heal, and often require therapy to strengthen the surrounding muscles.  It is important to understand how severe a sprain is, as the treatment can vary based on this severity.  Minor sprains simply need brief rest, ice, elevation, and some support via a simple brace or ACE wrap.  Moderate sprains need all of the above, but nearly always need a more comprehensive brace to keep the injured tissue from straining itself further.  Physical therapy may be needed shortly after the sprain settles down in order to restore strength of surrounding muscles, as well as the body’s unconscious ability to sense where the ankle is positioned relative to the body.  The ligaments themselves are not trainable, and they simply must scar themselves back into place in order to heal.  With scarring comes some limitation of motion, and that is why physical therapy can be helpful in restoring ankle function.  With severe sprains, immobilization in a walking boot or cast is very helpful for protecting the injured tissues.  Many times in severe sprains, the ligaments are completely disrupted.  Controversy exists as to whether the ligament should be repaired immediately, or if one should wait and see if long term instability and laxity (looseness)  of the ankle develops.  Regardless, severe sprains need to be well protected and properly treated to avoid long term ankle problems.  Long term problems include popping of the ankles, arthritis, and a tendency to re-sprain the ankle frequently without a significant injury.

One final thing to keep in mind with ankle sprains is the variety of injuries that can occur along with the sprain.  Fractures can certainly occur with ankle sprains, and may involve the ankle as well as the foot.  Any force severe enough to tear a ligament is sufficient to cause a fracture.  Ankle fractures are not uncommon, as are fractures to the bones alongside the outside of the foot.  One fracture in particular, the Jones fracture of the 5th metatarsal, is common when the foot rolls inward.  This fracture, as well as other less conspicuous fractures of the foot are often missed when one presents to an emergency room or family physician’s office for a sprain as the ankle injury dominates the symptoms.  Some fractures can be treated with simple casting, although most need surgery to repair the bone break.  Beyond bone and tendon, other injuries can occur to the tissues that surround the ankle and also bear the brunt of the injuring force.  This includes tendons that pass around and behind the ankle.  Tendonitis (an inflammation of tendon) can develop, and in less common instances a tear of the tendon or the muscle it attaches from can occur, further complicating the injury.

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