Radiographic features of the adult 3-M syndrome patient. On the lateral lumbar spinal radiograph (left panel), vertebral bodies are relatively tall and short. Lumbar hyperlordosis is caused by the short femoral necks. In the central panel, note the short femoral necks with anterior rotation of the pelvis (small foramina obturatoria). The ribs and the visible part of the femoral shafts are slender. The distance between the vertebral pedicles remains constant from L1 to L5. The tibia and fibula (right panel) are relatively inconspicuous. The radiographic features fitting with the diagnosis of 3-M are the tall and narrow vertebral bodies and slender tubular bones; other features of a chondrodysplasia, such as platyspondily or metaphyseal and epiphyseal changes, are typically absent.