Trauma to the bones of small infants from passive exercise: a factor in the etiology of child abuse.

Four infants, three premature and one term, developed serious bony injury from parent- or caretaker-administered passive exercises. In the three infants born prematurely, the exercise program was prescribed by neonatal intensive care unit staff before discharge; in the fourth infant, the babysitter initiated the program. In each case the passive exercise was begun to diminish actual or presumed muscle tightness. When these infants were presented to the physician with a serious traumatic injury between the ages of 4 and 10 months, the presumptive diagnosis of child abuse was made after radiologic assessment revealed multiple bone injuries. The several traumatic injuries to bones resulting from the home-administered physical therapy were most impressive. Passive exercise in three of the four infants was a significant factor in the cause of their injuries. Caution must be used in prescribing this form of "therapy" in small infants.