What is kyphosis?

Causes and Symptoms

Patients with kyphosis appear to be looking down with their shoulders markedly bent forward. They are unable to straighten their backs and their body height is reduced, causing their arms to appear to be disproportionately long. The increased curvature of the thoracic vertebrae tilts the head forward, and the patient has to raise his or her head and hyperextend his or her neck in order to look forward. This posture increases the strain on the neck muscles and leads to discomfort in the neck, shoulders, and upper back. It limits the field of vision and increases the patient’s chances of tripping over an object not directly in the line of vision. It also shifts forward the body’s center of gravity and increases the chances of falling.

In severe cases, kyphosis limits chest expansion during breathing. As a result, less air gets into the lungs, which become underventilated and prone to infections. Pneumonia
is a common cause of death in these patients. In very severe cases, the curvature of the thoracic vertebrae is so pronounced that the lower ribs lie over the pelvic cavity. Patients with severe kyphosis are not able to lie flat on their backs, and many spend most of their time sitting up in a chair or in bed, propped by a number of pillows. Unless the patient changes positions frequently, the pressure exerted by the vertebrae on the skin and subcutaneous tissue may precipitate pressure sores (bedsores)
on the upper back. Pressure sores may also develop on the buttocks. The sores often become infected, and the infection may spread to the blood, leading to septicemia and death.

The most common cause of kyphosis is osteoporosis, a disease in which the bone mass is reduced. As a result, the bones become mechanically weak and are unable to sustain the pressure of the body weight. The vertebrae gradually become wedged and partially collapsed, more so in the front (anteriorly) than in the back (posteriorly), thus increasing the forward curvature of the thoracic vertebrae. Sometimes, the compression of a vertebra is associated with sudden, very severe and incapacitating pain that is usually relieved spontaneously after about four weeks. In most cases, however, the compression is a gradual process associated with slowly worsening back discomfort. The discomfort is caused by the strain imposed on the muscles on either side of the vertebrae. In rare instances, the nerves exiting the spinal cord become trapped by the wedged or collapsed vertebrae, and the patient experiences severe pain that tends to radiate to the area supplied by the entrapped nerve.

Less common causes of kyphosis include the compression of a vertebra as a result of tumors or infections. In these cases, the angulation of the thoracic curvature is very prominent.

Treatment and Therapy

The availability of medications to treat and prevent osteoporosis, including alendronate and teriparatide, should significantly reduce the prevalence of both that disease and kyphosis. Severe cases of kyphosis or cases due to infection or tumor may require surgery.

Bibliography

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