Tib/Fib Instability

What is Tib/Fib Instability?

Tib/Fib instability, or high sprain syndrome, occurs when there is tearing and damage to the high ankle ligaments. These injuries are much less common than a traditional ankle sprain. The high ankle ligaments are located above the ankle, as opposed to the more commonly injured ligaments on the outside of the ankle. These high ankle ligaments connect the tibia to the fibula. It is important to have stability between the tibia and fibula at this level, because walking and running place a tremendous amount of force at this junction.

Anatomy

The high ankle ligaments connect the tibia and fibula and allow some rotation. There are three major components of this ligament complex. Ligaments connect bone-to-bone, whereas tendons connect muscle-to-bone, allowing them to move parts of the body.

1.     The first ligament is called the anterior inferior tibiofibular ligament, or AITFL, which runs in front of the two bones.
2.     The second is called the posterior inferior tibiofibular ligament, or PITFL, which runs in the back.  
3.     The interosseous (IO) membrane runs down the middle of these and provides a major support between the two bones. 

 

 
TibFib.1.png
TibFib2..png
 

Signs and Symptoms

High ankle sprains occur from rotational injuries, much like ankle fractures. They are common in sports, especially impact sports. An external rotation, when the foot is turned towards the outside with respect to the leg, most commonly causes these tears.  High sprain injuries are associated with prolonged recovery times and poorer outcomes than the more typical low sprain injuries.

Causes

High ankle sprains occur from rotational injuries, much like ankle fractures. They are common in sports, especially impact sports. An external rotation, when the foot is turned towards the outside with respect to the leg, most commonly causes these tears.