Picture it. You’re walking the dog down your neighborhood street, enjoying the scenery, when your dog suddenly lunges after a squirrel darting across her path. You take an unexpected step, stumble, and your foot rolls sideways. Ouch! You’ve just sprained your ankle. Now what? In this article, we’ll take a look at the anatomy of an ankle sprain. We’ll look closer at what structures actually get injured when you sprain your ankle as well as how this extremely common injury is usually treated.
What is an ankle sprain?
An ankle sprain is an injury to the ligaments and sometimes tendons around your ankle joint. Remember that your ankle is really two joints. It includes the tibiofibular joint where the tibia and fibula meet the talus and the subtalar joint where the talus meets the calcaneus. We have important ligaments and tendons that cross both of these joints. Remember that ligaments are connective tissue that connects bone to bone. Tendons are connective tissue that connects muscle to bone.
An ankle sprain happens when you move your ankle in a way that stretches the ligaments and tendons past the point that they can spring back. In more extreme types of ankle sprains, these ligaments and tendons might even tear, either partially or completely. An ankle sprain is one of the most common musculoskeletal injuries. It makes up about a quarter of all sports-related injuries (Struijs and Kerkhoffs, 2010).
What causes an ankle sprain?
Like the scene at the beginning of this article, an ankle sprain most often occurs when we trip, stumble, or fall for some reason. It might happen during a sport or athletic activity. It can also happen during a mundane moment in daily life. Less often, ankle sprains might be part of a significant trauma like a car accident. You might be more prone to ankle sprains if your ligaments have more laxity (are looser) than average or if you have biomechanical imbalances in your ankle(s) or lower body kinetic chain.
Anatomy of an ankle sprain
There are two types of ankle sprains, low ankle sprains and high ankle sprains. Let’s take a look at the specific differences in these two injuries.
Low ankle sprains
Low ankle sprains are the more common type. More specifically, these are sprains of the lower ligaments and sometimes tendons around the ankle. It’s usually the ligaments on the lateral side of the ankle that get overstretched or torn. The most common direction of an ankle sprain is a low ankle sprain where our foot moves too much, too quickly in the inversion direction, usually when our foot is also pronated. In this situation, the ligament that is most commonly overstretched or torn is the anterior talofibular ligament which attaches to the lateral malleolus (the bony lower portion of your fibula) and the talus.
Less commonly, you may also injure your calcaneofibular ligament in a low lateral ankle sprain. That ligament attaches to the lateral malleolus and the lateral portion of the calcaneus (your heel bone). The posterior talofibular ligament is also found on the lateral side of your ankle, but is much less commonly part of a sprain. It attaches to the lateral malleolus and the talus.
While it’s possible to sprain your ankle in a way that overstretches or tears ligaments on the medial side, that’s less common. However, that kind of injury can happen when your foot pronates and the back part of your foot (hindfoot) rotates. That combination of actions will lengthen the ligaments on the medial side of your ankle. The ligaments that could be injured in that kind of sprain include: the posterior tibiotalar ligament, the tibiocalcaneal ligament, the tibionavicular ligament, and the anterior tibiotalar ligaments. It’s also possible to injure the medial deltoid ligament by spraining your ankle during an eversion movement, but this is somewhat rare.
High ankle sprains
High ankle sprains are also called syndesmosis injuries or syndesmotic ankle sprains. They are slightly different than low ankle sprains. The syndesmotic complex is a fibrous area (considered a fibrous joint) where the tibia and fibula meet at their distal (lower) ends. You have several important ligaments that help maintain stability at this connection. Those are the anterior inferior tibiofibular ligament, the interosseous ligament, the posterior inferior tibiofibular ligament, and the deep transverse ligament.
In a high ankle sprain, there is damage to one or more of these upper ligaments. That can happen when we experience an injury during movement that includes external rotation of the leg and dorsiflexion of the ankle. High ankle sprains often accompany fractures of the ankle bones and/or the fibula because it takes a more significant amount of force to cause an injury to this area compared to the more common low ankle sprain. The pain locations are different too. The pain in this type of injury is commonly felt between the fibula and tibia. In this type of sprain, you might feel pain when going up or down stairs, or any other time you dorsiflex your ankle.
Symptoms
Common symptoms of ankle sprains include:
- Swelling
- Bruising
- Pain, especially when bearing weight on the injured ankle
- Ankle instability
- Reduced ankle mobility or range of motion in certain directions
How is an ankle sprain diagnosed?
For a very mild, brief stumble type of ankle sprain, you likely won’t need a formal diagnosis. A little ice and a few days of resting your ankle might be all you need. For a more serious ankle sprain, a doctor will conduct a physical exam. They might also do an X-ray to rule out accompanying broken bones. In a very serious sprain, they might suggest an MRI to better understand the extent of the injury and to best recommend a course of treatment.
Both low and high ankle sprains are graded according to their severity. In a grade one ankle sprain, the ligaments and/or tendons are overstretched, but not torn. In a grade two sprain, the fibers of ligaments or tendons are partially torn. In a grade three sprain, there is a complete tear of ligaments or tendons at the ankle joint.
Treatment
For the most acute treatment, icing your ankle and elevating it immediately after a sprain may help reduce swelling and inflammation. You’ll likely want to avoid weight-bearing on your injured ankle for a few days to a few weeks after a sprain. How long you avoid putting weight on your ankle depends on the severity of your injury. For a very mild strain, a few days of staying off it might be enough.
For a more severe injury, you should see a doctor for treatment recommendations specific to your situation. Your doctor may recommend wearing a temporary brace or using crutches to minimize weight bearing while your ankle heals. Additionally, they may recommend physical therapy exercises to stretch and strengthen the muscles around your ankle. They may also recommend manual therapy to mobilize and rebalance tissues around the ankle. For very severe injuries only, a cast may be required temporarily to stabilize the ankle or surgery could be recommended.
Conclusion
An ankle sprain is one of the most common musculoskeletal injuries. They can be caused by everything from a simple trip and fall incident in daily life to a more forceful injury during an athletic event. The specific structures injured are related to the position of the ankle and the direction of force during the injury. If you experience more than a very mild sprain, consult your doctor for an exam to determine the best course of treatment.
The course
Learn all 65 muscles in 3D, one lesson at a time.
12 modules · 79 lessons · 11 quizzes · 30-day guarantee.
