Physical therapy management of infants and children with hypophosphatasia.

Hypophosphatasia (HPP) is a rare inborn error of metabolism resulting in undermineralization of bone and subsequent skeletal abnormalities. The natural history of HPP is characterized by rickets and osteomalacia, increased propensity for bone fracture, early loss of teeth in childhood, and muscle weakness. There is a wide heterogeneity in disease presentation, and the functional impact of the disease can vary from perinatal death to gait abnormalities. Recent clinical trials of enzyme replacement therapy have begun to offer an opportunity for improvement in survival and function. The role of physical therapy in the treatment of the underlying musculoskeletal dysfunction in HPP is underrecognized. It is important for physical therapists to understand the disease characteristics of the natural history of a rare disease like HPP and how the impairment and activity limitations may change in response to medical interventions. An understanding of when and how to intervene is also important in order to optimally impact body function, lessen structural impairment, and facilitate increased functional independence in mobility and activities of daily living. Individualizing treatment to the child's needs, medical fragility, and setting (home/school/hospital), while educating parents, caregivers, and school staff regarding approved activities and therapy frequency, may improve function and development in children with HPP.