Definition – What is an orthosis for the foot?
Orthoses are aids that can be attached to different parts of the body from the outside. They serve to replace failed functions of the body part or a certain joint. This makes them suitable for chronic illnesses with irretrievable loss of function as well as for bridging acute injuries. On the foot, the orthoses generally serve to stabilize the ankle joint. But orthoses can also be used for the arch of the foot or the toes.
When do you need an orthosis for the foot?
Usually, orthoses on the foot are required to support ankle joint functions. For example, after an ankle fracture, an aircast splint is well suited to stabilize the ankle. Nevertheless, in contrast to a rigid cast, it is easy to occur with an aircast splint.
The orthoses are also used for ligament injuries to the ankle joint. Initially, hard orthoses are intended to prevent lateral tilting of the ankle joint. Softer bandages can be used when returning to sports.
These stabilize the ankle joint, but allow normal mobility. Another major disease area in which orthoses are used for the foot is paralysis of the lower leg and foot muscles. Orthoses are used for this purpose, which permanently replace the function of the paralyzed muscles or, in the case of a partial function of the muscles, support them.
A typical disease is the so-called weakness of dorsiflexion of the foot. This disease requires an orthosis that lifts the foot with every step. This is usually done with a splint that connects the foot to the lower leg and thus bridges the ankle joint, which can no longer be controlled by the paralyzed muscles.
Foot dorsiflexion
A weakness of dorsiflexion of the foot can have various causes. These are either directly related to the muscles that are responsible for lifting the foot (Musculus tibialis anterior = anterior tibial muscle, Musculus extensor digitorum/hallucis longus = long toe / big toe lifter). The nerve that supplies the muscles can also be affected (nervus fibularis profundus = deep nerve of the calf).
However, a disorder may already be present in the spinal cord, for example due to a herniated disc or in the brain (e.g. due to a stroke). Due to the weakness or complete paralysis of the foot lifter, the affected foot hangs down with every step. An orthosis connects the foot to the lower leg and thus bridges the weakened ankle joint.
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