Low or High? The Vast Difference Between Ankle Sprains
Ankle sprains come in more than one variety and can involve more than just the ankle joint. The type of sprain depends on the position of the foot at the time of injury as well as the nature of the force involved. The greatest distinction is between the more typical sprain and the high ankle sprain, an entirely different injury.
The typical ankle sprain
The most common sprain, to the lateral (outer) ankle, occurs when trauma to the area, usually entailing an inversion force (that rolls the ankle outward), stresses the ligaments in this region, thus disrupting joint stability. Ligaments, which connect bone-to-bone, can stretch mildly (a Grade 1 sprain), sustain moderate damage (Grade 2) or rupture completely (Grade 3).
There are a number of ligaments at the lateral aspect of the ankle, but those most often injured outline what looks like a bisected triangle. When the ankle is plantarflexed at the time of injury, (toes pointed downward), the ligament that is primarily injured is the one out front – the anterior talofibular ligament. Conversely, when the ankle is dorsiflexed (toes pointing up to the knee), the posterior talofibular, supporting the back of the joint is at risk. A more neutral position at the time of injury will most likely injure the stabilizer in the middle, the calcaneal fibular ligament, which has a more vertical orientation. It is the anterior ligament that is most frequently compromised.
Sprains to the medial (inner) aspect of the ankle do not occur nearly as often. That is because the primary stabilizer of this aspect of the joint, the deltoid ligament, is a very broad and sturdy structure. In addition, the ankle does not have as much inward mobility, offering far less range of motion into eversion (rolling the ankle inward) than inversion. So when trauma occurs – like landing awkwardly from a jump or landing on someone else’s foot when coming down with a rebound – the ankle typically rolls where the freedom of motion is greatest.
When the strong deltoid ligament is injured, the force may be such that it is transmitted upward resulting in a high ankle sprain as well as a high fibular fracture. The fibula is the narrower and outermost of the two bones of the lower leg. These injuries can also occur in isolation.
The high ankle sprain
A high ankle sprain typically results from a traumatic outward rotational force at the ankle that stresses the ligaments connecting the bones of the lower leg – the tibia and fibula – above the ankle.
This injury is not actually to the ankle at all. The joint involved is called a syndesmosis and (though it allows for some rotation), unlike most joints, it does not offer a great deal of movement. Along with its ligaments, the tibiofibular joint is really one whose purpose is to provide the stability necessary to withstand the great forces placed upon it with walking and running.
The three major ligaments connecting the lower tibia and fibula are the anterior inferior talofibular at the front of the syndesmosis, the posterior inferior talofibular at the back, and the interosseous membrane (inter = between and osseous = bone) supporting the area between the two bones.
High ankle sprains take longer to heal than typical ankle sprains. In the case of complete ligament rupture, they generally require surgery to ensure that the bones will align properly and sufficient stability is achieved. Surgery is rare even for severe ankle sprains of the low variety.
Non-operative healing time for most sprains will be up to 6 weeks and depend on the severity of the injury, the degree to which offending activities are limited and the effectiveness of rehab intervention. The ligament simply needs time to recover.
It is important to rest after any initial insult, control inflammation and decrease weight bearing to the degree necessary to allow for pain-free and normalized gait. The use of assistive devices such as crutches can be helpful toward this end. Temporarily bracing the ankle (with an aircast) is also very helpful. In spite of limiting activity, early movement should be encouraged to prevent the joint from stiffening.
Once injured, ligaments can remain more vulnerable because they may no longer provide the degree of stability that a joint had prior to initial insult. Strengthening the supporting musculature at the ankle is paramount so that the muscles provide more dynamic stability and act optimally to absorb shock.
Rehab also includes an exercise progression that incorporates balance activities, agility and endurance while also ensuring that the involved joints retain their normal ranges of motion.