Joint Mechanics: The Ankle and Foot
Playing sports, (specially contact sports like football, soccer or basketball) may expose you to injuries. Getting to know our joints is one and its mechanics can really help you improve how to train and play so you avid them. The ankle and foot hold the base of our body. This article shows you how both joints work and the mechanics behind them. Technical information you will find helpful.
The ankle joint is made up of the tibia and the talus bones. Because the end of the tibia is somewhat concave and the talus below it is convex, the bony stability is fairly strong. Since the ankle must withstand great stress, there are strong ligaments surrounding the joint to provide even greater stability.
Movements possible at the ankle are flexion and extension. The axis of rotation for the ankle is not in a true frontal plane. It is oriented slightly backward and onward on the lateral side. The tilt creates a slight disorientation of the foot from true anterior-posterior plane motion during plantar flexion and dorsiflexion. In other words the foot does not remain in the same position during its up and down movement.
The subtler joint is located between the talus and calcaneus. This is the joint that is typically involved in ankle sprains and strains. It is an intertarsal joint (involves several bones of the foot) while the ankle joint has only two bony parts, one in the shin and one in the foot. The subtler joint allows for different positions of the food and leg in response to weight bearing, particularly when running on uneven or curved paths. It is the main connection between foot and mobility and stability of the ankle and leg.
In plantar flexion there are simultaneous movements of the foot around the subtalarand ankle axes (example: a combination at the ankle joint). There is combination of inversion at the subtalar joint and dorsiflexion at the ankle when executing ankle joint flexion.
Having muscle strength on both sides of the ankle and foot is important in maintaining joint integrity. Any imbalances in the strength or flexibility of the surrounding musculature result in misalignment. This in turn must be counteracted by muscular contraction or ligament tension. If not, postural imbalances occur.
People with shisplints usually have significantly greater plantar flexor (extensor) strength than dorsiflexor (flexor) strength and greater movement of the calcaneus during the support phase of walking and running. Overdevelopment of the ankle extensors tend to also cause a muscular imbalance between the strength of the foot supinator and the pronator muscles, which may result in lateral ankle sprains, particularly when landing after being airborne.
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