Ankle Sprains, Mechanism of Injury, and Related Anatomy:

There are a couple different kinds of sprains that can happen in the ankle. The different kinds of classifications are based on what ligament was injured and the severity. 

The most common ankle sprain is what’s called an inversion ankle sprain. This is when your foot turns inward under your leg and the outside of your ankle gets stretched rapidly. The ligament that gets injured in this case is called your ATFL, anterior talofibular ligament, and it is the most commonly sprained ankle in the whole body! This type of injury is very common among recreational athletes and professional athletes alike. Basketball players will often get this injury when they land on someone else’s foot nad “roll” their ankle. 

 The second type of ankle sprain is called an eversion ankle sprain. This where your foot turns outward under your leg and the ligaments on the inside, or medial side, of your ankle get stretched. The ligament that gets injured is called your deltoid ligament and this is a much less common injury. This can also be injured if the arch of your foot collapses rapidly. Both of these ankle injuries are considered what is called a low ankle sprain because it occurs below the level of the ankle.


When a ligament stretches beyond its normal limit, a sprain occurs. While most sprains respond quickly to treatment, up to 40% of patients will develop chronic ankle instability that makes it easy to re-injure the ankle. Grade I sprains (mild) occur when the ligaments are overstretched, but only a small number of fibers are torn. With grade II sprains (moderate), the ligament is partially torn, but with more fibers involved than grade I, causing swelling, bruising, extensive pain, difficulty bearing weight and joint instability. In grade III sprains (severe), the ligament is completely torn, can using severe pain, widespread swelling and bruising, loss of joint function and an inability to bear weight.

The final type of ankle sprain is called a high ankle sprain because the tissue that is injured is actually above the ankle. There is a piece of connective tissue called a syndesmosis that connects your two lower leg bones, your tibia and fibula, to each other in your leg. This structure can get injured when the bones spread apart. This can happen when the ankle is flexed upward and then rotated outward to where the top bone in your foot actually spread apart your tibia and fibula. This type of injury usually has a longer recovery and can keep an athlete sidelined for a little longer.

It has been shown that dorsiflexion and external rotation causes increased tension to the ligaments at the distal tibiofibular joint. This mechanism causes the talus to rotate and as a result can cause separation between the tibia and fibula stressing the ligaments, or worst case scenario, causing a rupture. The external rotation mechanism has been shown to affect the tibiofiabular ligaments and risk injury to the interosseus membrane with overstretching the space between the tibia and fibua bones. The normal gap between the tibia and fibula via the interosseous membrane is very small and approximately 5 mm.

If you’re still battling pain you can’t seem to shake and this problem is limiting you from doing the activities that you LOVE, give us a shout today at 561-899-8725 or email us directly at we can directly diagnose what the problem is and how to solve it together for the long-term.


Imagine getting that pain fixed – allowing you to really get after your workouts and do the activities you LOVE most in life. We can help solve this problem for you.

Have other questions or need assistance with a current injury? Reach out to us and learn how we may be able to help!