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Your spine (vertebral column) is composed of bones (vertebrae), which are held together by tough, fibrous bands (ligaments). The vertebral column consists of seven neck (cervical) vertebrae, 12 middle back (thoracic) vertebrae and five lower back (lumbar) vertebrae. Lumbar vertebrae are the largest, and they carry most of your body’s weight. The sacrum, containing five fused vertebrae, is below the lumbar vertebrae. The last three tiny vertebrae, also fused together, are called the tailbone (coccyx).

Kyphosis is a forward rounding of the vertebrae in your thoracic spine. The vertebrae in your thoracic spine connect to your ribs.Causes of kyphosis depend on the different types of kyphosis.

Kyphosis can be congenital (present at birth), or due to acquired conditions that may include metabolic problems,neuromuscular conditions, osteogenesis imperfecta, spina bifida, and Scheuermann’s disease. Kyphosis is a spinal deformity that can result from trauma, developmental problems, or degenerative disease. Kyphosis can occur at any age, although it is rare at birth. Vertebrae can be fused together, shaped wrong, extraneous, or partially missing. Congenital and hereditary defects in bone growth weaken bone and result in exaggerated curves wherever gravity or muscles pull on them. Dwarfism is such a defect. During life, several events can distort the spine. Because the natural tendency of the thoracic spine is to curve forward, any weakness of the supporting structures will tend in that direction. A diseased thoracic vertebra (a spine bone) will ordinarily crumble its forward edge first, increasing the kyphotic curve. Conditions that can do this include cancer, tuberculosis, Scheuermann’s disease, and certain kinds of arthritis. Healthy vertebra will fracture forward with rapid deceleration injuries, such as in car crashes when the victim is not wearing a seat belt. Adolescent kyphosis, also known as Scheuermann’s disease, results from the wedging together of several consecutive vertebrae (bones of the spine). The cause of Scheuermann’s disease is unknown. In adults, kyphosis can be a result of osteoporotic compression fractures (fractures caused by osteoporosis), degenerative disease (such as arthritis), or spondylolisthesis (slipping of one vertebra forward on another).

There are three main types of abnormal kyphosis: postural kyphosis, Scheuermann’s kyphosis, and congenital kyphosis.

Postural kyphosis is the most common type of kyphosis. This is more common in girls than in boys and is typically first noticed during adolescence. It is caused by poor posture and a weakening of the muscles and ligaments in the back (paraspinous muscles). The vertebrae are typically shaped normally in postural kyphosis. It is often slow to develop and usually does not continue to become progressively worse with time. These patients can have symptoms of pain and muscle fatigue. This type of kyphosis does not lead to a severe curve with a risk of neurologic, cardiac, or pulmonary problems.

Scheuermann’s kyphosis also is first noticed during adolescence. This type of kyphosis is the result of a structural deformity of the vertebrae. It is more common to develop scoliosis (kyphoscoliosis) with Scheuermann’s kyphosis than with the other types of kyphosis. The diagnosis requires X-rays to show a wedge of at least 5 degrees at the front of at least three neighboring vertebral bodies. The reason for this abnormal wedging of the vertebrae is not well understood.

Congenital kyphosis is the least common type of abnormal kyphosis. This is caused by an abnormal development of the vertebrae during development prior to birth. This can lead to several of the vertebrae growing together (fusing) in kyphosis.

Causes:

1.Conditions that cause paralysis, such as cerebral palsy and polio, and that stiffen the bones of the spine
2.Spina bifida, a birth defect in which part of the spine doesn’t form completely, and which causes defects of the spinal cord and vertebrae.
3.Cancer or benign tumors that impinge on bones of the spine and force them out of position
4.Tuberculosis and other infections of the spine, which can result in destruction of joints
5.Connective tissue disorders, such as Marfan syndrome, that may affect the connective tissue’s ability to hold joints in their proper position
6.Ankylosing spondylitis, an inflammatory arthritis that affects the spine and nearby joints
7.Degenerative arthritis of the spine, which can cause deterioration of the bones and disks of the spine
8.Osteoporosis, a bone-thinning disease that’s associated with fractures of the vertebrae, which cause compression of the spine and contribute to kyphosis.

Structural problems:There are several conditions that can affect the structure of the spine and cause kyphosis (see the box, right).Kyphosis can be present at birth (congenital) when parts of the spine do not develop properly, though this is rare.The structural problems that can lead to kyphosis are listed below.

Bad posture:Bad posture over a long period of time is a common cause of kyphosis. For example, if you slouch when you stand up, this stretches your spinal ligaments and can increase the natural curvature of your spine.Postural kyphosis is more common in girls than boys and is slow to develop. It usually occurs during adolescence and generally will not get any worse with time.

Adolescent kyphosis is also known as Scheuermann’s disease, juvenile kyphosis, vertebral epiphysitis and it is the most common form of this disorder and it may result from growth retardation or a vascular disturbance in the vertebral epiphysis during periods of rapid growth or from congenital deficiency in the thickness of the vertebral plates. Other various causes include:

1.Injuries such as a car crash and disk degeneration
2.Aseptic necrosis
3.Inflammation
4.Infection

Adult kyphosis may result from:

1.Other conditions, such as arthritis, Paget’s disease, polio, compression fracture of the thoracic vertebrae, metastatic tumor, plasma cell myeloma, or tuberculosis.
2.Prolonged steroid therapy
3.Endocrine disorders, such as hyperparathyroidism and Cushing’s disease
4.Aging and associated degeneration of intervertebral disks, atrophy, and osteoporotic collapse of the vertebrae