Plantar flexion: Function, anatomy, and injuries

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Plantar flexion Contracture is a condition resulting in the inability to bring the ankle to 0º by passive range of motion. This is caused by shortening of the muscles and tendons that plantarflex the ankle. The most commonly affected are the Achilles Tendon and the Deltoid Ligament. An ankle position of 0º is regarded as the normal position of the ankle. A cruder way to access this is to ensure that the ankle is perpendicular to the lower leg. Ankle Flexion Contracture can result from untreated Foot Drop. Foot Drop and Contractures are common in stroke patients who have experienced some paralysis or nerve damage to the muscles posterior to the lower leg.

A contracture happens whenever a muscle remains in its shortened position. This reduces the total movement the joint should have normally. In the case of a Plantarflexion contracture, the effected joint is the ankle. The muscles on the back of your calf are called the Plantar flexors, they consist of the gastrocnemius and the soleus.

Moderate to severe Plantar flexion contractures occur very frequently in people who have been born with Cerebral Palsy, had a stroke or suffered some other form of nerve damage. More mild forms of Plantarflexion contracture can affect a significant amount of the population. The mildest form of Plantarflexion contractures would present itself when a patient is unable to pull the dorsal surface of their foot towards them and past the neutral position.

People with Plantar flexion contractures tend to compensate the lack of ankle flexion by moving their knees into bad alignment when walking or standing. This causes stress to the knee joint as there is more flexion applied throughout the entire gate cycle. This increases the effect that the ground reaction force has on the knee joint during initial contact. The contracture can also cause the hamstrings to feel tight and uncomfortable for the patient. The tightness of the hamstrings causes them to pull on the hip, this has an adverse effect on the lumbar vertebrae causing a sensation of stiffness and pain in the patients back. Due to the knock-on effect associated with tautness of muscles from the calf to the hip, a multitude of symptoms can be observed. Usually patients will feel pain and fatigue in their feet, legs and back.

The symptoms of Mild Plantarflexion contracture can be elevated by the use of orthotic insoles, these are used to lift the heal up and alleviate strain. This solution essentially brings the floor up to the foot – It makes up for the fact that the person cannot get his or her foot into the neural position. In fact, it encourages the foot to remain in a nice relaxed Plantarflexed position. The problem with this solution is that patient cannot always have a wedge under their heel. This means that the problem will not be alleviated when the patient is walking without their shoes on. If worn for an extended period of time, the patient may become dependent on the heel elevation to be able to walk without pain. This position would essentially function as a new normal amount of flexion of the foot. If maintained long enough, the foot loses its ability to dorsiflex even to the neutral position. The patient has now moved to a more severe level of Plantar flexion contracture. A Fixed AFO may be then used to help reduce the rate of the excessive plantar flexion.