A progressive, hereditary disease characterized by weakness and atrophy of muscle without involvement of the nervous system. There is eventual involvement of all skeletal muscles, with paralysis of the respiratory muscles, including the intercostals, diaphragm, and accessory muscles.

There are eight types of muscular dystrophy. Duchenne's muscular dystrophy is an X-linked, recessive condition in which females carry the affected genes. It is the most common type. Other types with common orthopaedic problems include:

• Facioscapulohumeral dystrophy,

• Limb-girdle muscular dystrophy,

• Becker muscular dystrophy, and

• Myotonic dystrophy.

Less common muscular dystrophies include:

• Oculopharyngeal muscular dystrophy,

• Congenital musculary dystrophy, and

• Distal muscular dystrophy.

Manifestations include:

• muscle weakness;

• lack of coordination;

• clumsy gait;

• inability to lift the arms over the head; and

• progressive crippling, resulting in loss of mobility.

A complete history and physical examination are needed because diagnosis is based on clinical findings that are characteristic of the condition, age of onset, and family history. Electromyography (EMG), muscle biopsy, and dystrophin immunostaining confirm the diagnosis. Electromyography reveals short, weak bursts of low-amplitude electrical activity in affected muscles. Muscle biopsy shows necrosis and variation in muscle-fiber size. Dystrophin analysis of muscle samples is the diagnostic test of choice. Creatine kinase is elevated in Duchenne type and less elevated in Becker type and other muscular dystrophies.

Since there is no cure for muscular dystrophy, no specific treatment exists to stop the progressive muscle impairment. Treatment involves trying to minimize the deformities through physical therapy. Daily doses of prednisolone may be used to achieve significant, long-term clinical improvement. Moderate exercise with bracing may be encouraged as long as possible, and surgery, implemented to correct contractures, may help to preserve mobility and independence. Passive exercises may extend the period of ambulation. Patient and family teaching, and genetic counseling may be indicated.

Muscular dystrophy is a crippling disease. In most cases the arms, legs, and spine become progressively weakened and deformed, requiring the use of a wheelchair. Pulmonary problems develop late in the disease process due to paralysis of respiratory muscles.