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Kyphosis

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A healthy spine (left) has slight curves that allow a person’s weight to be supported in an upright position. When the spine develops an abnormally large curve just below the neck (right), the condition is called kyphosis.

Kyphosis is an exaggerated forward curvature of the spine. The word kyphosis is from the Greek kyphos, which means hump, and the condition is also known as humpback, round back, or dowager’s hump.

Normally, the spine has a slight curve to it that allows a person’s weight to be supported in an upright position. A normal thoracic spine extends from the 1st to the 12th vertebra and should have a slight angle, ranging from 20 to 45 degrees. When the curve is greater than 45 degrees, it is called kyphosis or hyperkyphosis. While many people with kyphosis may treat the condition with physical therapy, severe forward curvature of the spine can be debilitating and needs to be addressed with surgery. Severe kyphosis can deform the chest and affect the lungs and heart, leading to breathing difficulties, fatigue, and even heart failure. Digestion problems can result, too, as well as neurological issues from compression of the nerves in the spine.

What Causes Kyphosis?

Kyphosis has a range of causes, most of which lead to weakening of the spinal structure and subsequent collapse of the front of the vertebrae as the back of the vertebrae retain their height; this results in the spinal column tipping forward and a person assuming the characteristic round, stooped posture.

  • Arthritis can lead to an excessive curve of the spine. Osteoarthritis of the spine erodes the joints connecting the vertebrae, causing joint inflammation, pain, and stiffness. Ankylosing spondylitis is a form of arthritis in which chronic inflammation causes stiffness and pain in the spine. In severe cases, the bones of the spine can fuse together over time, causing rigidity and a hunched posture, or kyphosis. Systemic arthritis (such as rheumatoid arthritis) can bring on inflammation of the tissue surrounding the thoracic spine, thus weakening it.
  • Cancers (such as bone cancer, multiple myeloma) or tumors can lead to kyphosis. Chemotherapy and radiation to the spine and skull for cancer treatment can damage the spine as well and make a person more prone to compression fractures, which lead to the vertebrae becoming wedge-shaped.
  • Congenital kyphosis is a condition caused by a spinal defect that a person is born with. An incomplete formation of the spine can lead to an extreme kyphosis. Congenital kyphosis is the most common cause of paralysis of the lower part of the spine (paraplegia) that isn’t related to trauma or infection.
  • Developmental conditions such as Scheuermann’s disease, the most classic form of kyphosis, is the result of wedged vertebrae that develop during the adolescent growth spurt and can lead to a thoracic curve between 45 and 75 degrees. Schmorl’s nodes, small herniations of the cushioning discs between each vertebra, can result from the compression. The spinal ligaments thicken and further contribute to the curvature and the wedging of the discs. This is a disease that has a high genetic component, which means that it seems to run in families. Twenty to 30 percent of people with Scheuermann’s disease also have some degree of scoliosis.
  • Disc degeneration, as a normal result of aging, can cause the circular discs that act as cushions between spinal vertebrae to dry out and shrink, causing the vertebrae to collapse on one another and pitch the spine forward.
  • Marfan syndrome, or Prader-Willi disease, is a genetic disorder of the body’s connective tissue that commonly affects the spine.
  • Osteoporosis is a disease in which the bones lose their density, becoming very thin and brittle. This leads to an increased likelihood of compression fractures of the spine that typically result in vertebrae morphing into a wedge shape, which results in kyphosis. 
  • Paralytic disorders (conditions that lead to paralysis) and neuromuscular disorders can eventually lead to kyphosis. Polio, cerebral palsy, spinal muscle atrophy (an inherited illness that causes muscle wasting), spina bifida, or muscular dystrophy can cause kyphosis as a secondary effect.
  • Post-surgical complications/iatrogenic kyphosis (iatrogenic means as a result of medical intervention) — such as when a spinal fusion surgery does not heal properly and the ligaments are not strong enough to support the spine, which causes the vertebrae to collapse — often requires a second, revision surgery to correct the kyphosis. Post-laminectomy kyphosis is the most common type of iatrogenic kyphosis.
  • Postural kyphosis is a result of slouching, and the body often compensates for the forward curve of the thoracic, or upper spine, with an excessive curve of the lower, or lumbar, spine in the opposite direction.
  • Trauma that results in injury to the spine, such as a vertebra fracture in the thoracic (upper) or lumbar (lower) spine, will almost always lead to some degree of kyphosis.

 

Reviewed by: Kai-Ming Fu, MD, PhD
Last reviewed/last updated: June 2018
Illustration by Thom Graves, CMI