What types of lower leg orthoses are available?
Depending on the indication, different lower leg orthoses can be used. A distinction is made between dynamic and fixed lower leg orthoses. The dynamic orthoses usually have a joint that is located at the level of the ankle joint.
This enables movements in the ankle joint. They are therefore suitable for persons whose musculature is sufficient to control the ankle, but where the force is not sufficient to stabilize the lower leg sufficiently. However, most lower leg orthoses do not contain a joint.
Instead, they bridge the ankle joint, since affected persons with weakness of dorsiflexion of the foot, for example, can no longer lift their foot independently. Without the orthosis, they would often stumble. With these fixed orthoses there are some that are suitable for flaccid paralysis and some that are used for spastic paralysis.
In flaccid paralysis, the muscles can no longer be controlled, so the foot and lower leg require support. Spastic paralysis is caused by increased muscle tension, which also restricts mobility and makes it difficult to control the lower leg. With the lower leg orthoses used, a distinction can also be made between particularly light material such as carbon and somewhat heavier orthoses made of hard plastic.
Dynamic lower leg orthoses can have a joint that sits at the level of the ankle joint, allowing it to move while stabilizing the foot and lower leg. However, an orthosis made of particularly elastic material can also be described as dynamic. In this case, the foot and lower leg are firmly embedded in the orthosis, the connection between the two parts is made of supporting but somewhat flexible material so that a certain degree of mobility is maintained in the ankle joint.
The strength of the dynamic orthosis can be adjusted according to the weakness of the affected person. Lower leg orthoses with joint have their joint at the level of the ankle joint. This makes it possible to stabilize the independent movements of the affected person in the ankle joint without restricting mobility.
Such a joint can be left free, but it is also possible to allow only a certain range of motion. For example, in the case of paralysis of the foot lifter muscles, the lowering of the foot can be prevented with every step, but a push off at the end of the step is possible. Malpositions of the ankle joint can also be corrected and held.
This includes an inward or outward tilted ankle joint or a pointed foot. Also interesting at this point is the overview of foot malpositions: Overview of foot malpositionsPeople with a pointed foot cannot put their heel on the ground because the ankle joint is fixed in an extended position. This means that affected persons would have to walk on their tiptoes without an orthosis.
With the help of orthoses with a joint, this toe position can be gradually corrected. In this way, the foot is stabilized with every step, the angle of the joint is adjusted slightly smaller week by week until the pointed foot has become a foot that can be angled up to 90° in the ankle joint. Stiff orthoses can also be used for the pointed foot, but their angle must be adjusted according to the progress of the therapy. The following article is also interesting at this point: Orthosis for the foot
