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An orthosis is defined by the international Organization for Standardization as an “externally applied device used to modify the structural and functional characteristics of the neuromuscular and skeletal systems.” Orthoses may be used to decrease pain, provide stabilization for healing, prevent or correct a deformity, improve function, or any combination of these. Over the past 75 years, the profession has evolved from one of artisanal work involving carving wood and bending metal, to a science involving microprocessors, composites, and computer-aided design and manufacturing. Although materials and processes have changed, orthotic design remains largely custom or customized for the individual patient. The orthotist must consider the pertinent patient history, underlying pathologies, the biomechanical system and the impact of the orthosis on this system, sensation, skin integrity, the prognosis, as well as patient preferences and desired goals when determining optimal orthotic care. This is done in coordination with family, physicians, therapists, and other members of the health care team. This chapter will review basic orthotic designs and management principles for the upper limb, lower limb, and spine.
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UPPER EXTREMITY ORTHOTICS
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The anatomy of the upper limb allows for both tremendous range of motion and manual dexterity. Effective orthotic treatment optimally preserves functional range and provides for a stable hand for prehension and tactile input, when possible. Grasp is most often achieved with the thumb against the index finger and middle finger. This requires a stable positioning of the thumb in opposition. Upper limb orthoses can be static, static progressive, or dynamic, or a combination of the three. Static orthoses hold the limb in a specific position, either to prevent unwanted motion or to enable function. Static progressive orthoses are used to increase range of motion by gradually altering the position of a joint or joints as the patient's range of motion or strength changes. Dynamic orthoses allow for volitional movement to occur, then the orthosis will return the limb to a resting position. This is used most frequently when a muscle action is no longer functioning, but the antagonist is. An in-depth knowledge of the specific individual pathologic presentation is necessary to design the orthosis.
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Orthoses for the Fingers and Hand
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There are several disorders of the fingers involving fractures, soft tissue contractures, or ruptures. A Mallet Finger is flexion at the distal interphalangeal (DIP) joint of a finger that cannot be straightened. The Swan-Neck Deformity involves hyperextension of the proximal interphalangeal (PIP) and flexion of the DIP. This also occurs in individuals who have Rheumatoid Arthritis or Ehlers–Danlos Syndrome. A Boutonniere Deformity is the reverse of the Swan Neck, with hyperextension of the DIP and flexion of the PIP (see Fig. 79–1).
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