Achondroplasia: manifestations and treatment.

Achondroplasia, the most common skeletal dysplasia, is caused by a mutation of fibroblast growth factor receptor-3. This disorder is characterized by frontal bossing, midface hypoplasia, otolaryngeal system dysfunction, and rhizomelic short stature. Orthopaedic manifestations are exhibited in the spine and the extremities. In the infant with achondroplasia, foramen magnum stenosis may result in brainstem compression with apnea and sudden death. Thoracolumbar kyphosis is seen in most infants, but typically it resolves when the child begins to walk. Anatomic anomalies of the vertebral column place the patient at risk for spinal stenosis as early as the first decade and especially during adulthood. Radial head dislocation is one manifestation in the upper extremity. Lower extremity alignment often is characterized by genu varum, which may require correction osteotomy. Medical and surgical options are available to increase patient height, but indications are controversial, and treatment often consumes a large portion of the child's life.