**3. Clinical manifestations**

KD occurs more frequently in the middle and in the elderly slightly predominant in males [7]. The incidence of KD in elderly patients ranges from 7 to 37%. One of the characteristic symptoms is an acute pain especially in the early stages of the disease usually without accompanying neurological symptomatology. In these cases, falls are generally conditioning factors of pain. The kyphotic deformity associated with recurrent pain of greater intensity in later stages usually corresponds to the collapse of the vertebral bodies and is usually located in the thoracolumbar region. Then neurological signs such as weakness of the lower extremities, paresthesias, as well as neuropathies that interfere with normal function of the digestive tract and bladder can develop.

Steel related the KD to insignificant trauma generally involving the 3rd thoracic vertebra and the 2nd or 3rd lumbar vertebra predominantly observed in males. He also described five stages namely *initial insult*, characterized by hyperflexion of the spine and association to the trauma of variable type and severity, in addition to normal roentgenograms. The second stage or *posttraumatic period* was manifested by mild back pain without functional limitation. The third stage, *latent interval or state of relative well-being*, was characterized by progressive disability in the following week or months of the traumatic event, not incapacitated. In this period, variability in time from 4 weeks to 1 year has been described [2, 5, 7, 11, 14–18, 20–23]. Fourth stage or *recrudescent stage*, in this the patient presents localized, persistent back pain, tenderness, and tendency to peripheral irradiation. In the last stage or *terminal stage*, the patient develops permanent kyphotic deformity with or without progressive pressure on roots or spinal cord [2].

Neurological symptoms are usually absent in the early stages of the disease and when pain occurs in the thoracolumbar region this usually corresponds to the collapse of the vertebral body. In the advanced stages, the patient develops paresthesias, lower extremity weakness, and bowel/bladder disturbance [7]. Besides, the kyphotic deformity associated with osteoporotic vertebral fracture limits the functionality and has repercussions on the quality of life of the patient. In addition, it increases the mortality and incidence of fractures in adjacent bone structures [25, 26].
