As a rule, an orthosis is a therapeutic appliance manufactured by an orthopaedic technician for stabilization, relief, immobilization or positional correction of limbs or the trunk. They are used after fractures, operations, paralyses, inflammations, rheumatism as well as in cases of insufficient flexion or extension. In part, they can replace lost functions, in part their use prevents sequelae - for example by false posture or malposition - and prevent the wear of affected parts of the body.

Orthoses can be classified by their areas of application (leg, arm, trunk etc.) and by their function (fixation, stabilization etc.).

The disorders for which orthoses can be used vary in form and function. . An orthopedic technician must manufacture or at least adjust an orthosis, so that it fits correctly and can function efficiently.  Depending upon the orthosis, this may be relatively simple or very time-consuming.

Orthoses that are frequently used during the therapy of fibular and tibial defects: