A previously asymptomatic 62-year-old woman presents with sudden onset of severe midback pain. X-rays reveal an anterior compression fracture of T10. Other vertebral bodies show decreased mineral density and prominent vertical striations. Which of the following is the most likely diagnosis?

The vertebral bodies in osteoporosis may become increasingly biconcave because of weakening of the subchondral plates. This results in "codfish" vertebra. When vertebral collapse occurs, the anterior height of the vertebra is usually decreased. Plain x-rays are insensitive diagnostic tools because up to 30% of bone mass can be lost without any apparent x-ray changes. Dual-energy x-ray absorptiometry (DEXA) and CT scan are more sensitive tests for bone loss, but their exact clinical role has not been clearly established.