An Overview:
Ankle sprains often result in a loss of foot pronation which in turn disrupts the hip biomechanics necessary for the loading and unloading phases of activities like walking. Because of the disruption of hip biomechanics, the low back must compensate for a loss of normal shock absorption at the hip and a common side-effect is low back pain. Quickly restoring normal foot mechanics is essential for pain free walking and other activities.
The detailed version:
Most ankle sprains are the result of an inversion and plantar flexion movement to an extreme, uncontrolled range. Typically, the anterior talofibular ligament is overstretched and the result is pain and inflammation. It should be noted that if you cannot walk immediately after the ankle injury or meet any of the other Ottawa ankle rules criteria, it is important to visit a doctor who can do an x-ray.
After the typical inversion ankle sprain, foot pronation is lost – specifically, subtalar joint eversion combined with adduction and plantarflexion. Foot pronation allows the tibia to internally rotate which then allows the femur to internally rotate. The result is hip internal rotation, adduction and flexion which are the 3-planes of motion that maximally stretch the glutes and provide those muscles with the optimal ability to help decelerate gravity and reduce shock absorption at foot strike.
The loss of subtalar joint eversion means there will be less ability for the hip to accept ground reaction forces. Instead of the low back experiencing controlled and cushioned motion, it will experience excessive stress. The result is low back pain which may manifest on either side.
Sometimes, the fibular head may shift forward as a result of the sprain and if this occurs, it is essential that functional manual reaction be used to mobilize the foot into pronation while slowing down the fibular head’s forward motion in space. The sooner normal foot pronation and fibular head mechanics are regained, the sooner the ankle will feel better and the normal chain reaction biomechanics will be restored – this will result in an ankle that feels better faster and a back that will stay healthy.
Quickly and safely restore normal ankle motion after a typical inversion ankle sprain: