AP and lateral radiographs of the lumbar spine show the features of achondroplasia. The posterior vertebral bodies are scalloped, with a mild scoliosis of the lumbar spine. Notice the marked sacral lordosis. Patients with achondroplasia are at risk for spinal stenosis due to the narrowed dimension of the spinal canal in both the anterior-posterior and medial-lateral dimensions due to short pedicles and narrowed interpediculate intervals (illustrated on the AP radiograph). There is also mild hypoplasia of the vertebrae at the thoracolumbar junction.