Orthotics is the design, fabrication, fitting and supervised use of devices that provide external support or assist weak or abnormal joints and/or muscle groups. Musculoskeletal disorders, joint weakness, back problems, or the inability of any joint or muscle group to function correctly can greatly decrease an individuals quality of life and general mobility. These problems can be caused by congenital factors, traumatic injury, chronic conditions, sports injuries, or degenerative disease.

Orthotics is the scientific field dedicated to helping the victims of musculoskeletal disorders by providing the appropriate corrective, assistive, and supportive devices. In some instances, it is necessary to design and fabricate a custom orthosis for a specific need. In others, the orthotist custom fits an off-the-shelf device to the patient's dimensions, or incorporates additional components to achieve the desired results.

An orthosis may be worn temporarily until a weakness or injury is overcome, or on a permanent basis to facilitate impaired function due to a congenital or degenerative condition.