Kyphosis (from Greek – kyphos, a hump), also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae (upper back). It can be either the result of degenerative diseases (such as arthritis), developmental problems (the most common example being Scheuermann's disease), osteoporosis with compression fractures of the vertebrae, or trauma. A normal thoracic spine extends from the 1st to the 12th vertebra and should have a slight kyphosis ranging from 20° to 45°. When the "roundness" of the upper spine increases past 45° it is called "hyperkyphosis". Scheuermann's kyphosis is the most classic form of hyperkyphosis and is the result of wedged vertebrae that develop during adolescence. The cause is not currently known and the condition appears to be multi-factorial and is seen more frequently in males than females. 
In the sense of a deformity, it is the pathological curving of the spine, where parts of the spinal column lose some or all of their lordotic profile. This causes a bowing of the back, seen as a slouching posture.
While most cases of kyphosis are mild and only require routine monitoring, serious cases can be debilitating. High degrees of kyphosis can cause severe pain and discomfort, breathing and digestion difficulties, cardiovascular irregularities, neurological compromise and, in the more severe cases, significantly shortened life-spans. These types of high end curves typically do not respond well to conservative treatment, and almost always warrant spinal fusion surgery, which can successfully restore the body's natural degree of curvature. The Cobb angle is the preferred method of measuring kyphosis.
There are several kinds of kyphosis (ICD-10 codes are provided):
Postural kyphosis (M40.0), the most common type, normally attributed to slouching, can occur in both the old and the young. In the young, it can be called 'slouching' and is reversible by correcting muscular imbalances. In the old, it may be called 'hyperkyphosis' or 'dowager’s hump'. About one third of the most severe hyperkyphosis cases have vertebral fractures. Otherwise, the aging body tends towards a loss of musculoskeletal integrity, and kyphosis can develop due to aging alone.
Scheuermann's kyphosis (M42.0) is significantly worse cosmetically and can cause varying degrees of pain, and can also affect different areas of the spine (the most common being the mid-thoracic area). Scheuermann's disease is considered a form of juvenile osteochondrosis of the spine, and is more commonly called Scheuermann's disease. It is found mostly in teenagers and presents a significantly worse deformity than postural kyphosis. A patient suffering from Scheuermann’s kyphosis cannot consciously correct posture. The apex of the curve, located in the thoracic vertebrae, is quite rigid. The patient may feel pain at this apex, which can be aggravated by physical activity and by long periods of standing or sitting. This can have a significantly detrimental effect on their lives, as their level of activity is curbed by their condition; they may feel isolated or uneasy amongst peers if they are children, depending on the level of deformity. Whereas in postural kyphosis, the vertebrae and disks appear normal, in Scheuermann’s kyphosis, they are irregular, often herniated, and wedge-shaped over at least three adjacent levels. Fatigue is a very common symptom, most likely because of the intense muscle work that has to be put into standing and/or sitting properly. The condition appears to run in families. Most patients who undergo surgery to correct their kyphosis have Scheuermann's disease.
Congenital kyphosis (Q76.4) can result in infants whose spinal column has not developed correctly in the womb. Vertebrae may be malformed or fused together and can cause further progressive kyphosis as the child develops. Surgical treatment may be necessary at a very early stage and can help maintain a normal curve in coordination with consistent follow-ups to monitor changes. However, the decision to carry out the procedure can be very difficult due to the potential risks to the child. A congenital kyphosis can also suddenly appear in teenage years, more commonly in children with cerebral palsy and other neurological disorders.
Nutritional kyphosis can result from nutritional deficiencies, especially during childhood, such as vitamin D deficiency (producing rickets), which softens bones and results in curving of the spine and limbs under the child's body weight.
The Milwaukee brace is one particular body brace that is often used to treat kyphosis in the US. Modern CAD/CAM braces are used in Europe to treat different types of kyphosis. These are much easier to wear and have better in-brace corrections than reported for the Milwaukee brace. Since there are different curve patterns (thoracic, thoracolumbar and lumbar), different types of brace are in use, with different advantages and disadvantages.
Modern brace for the treatment of a lumbar or thoracolumbar kyphosis. The brace is constructed using a CAD/CAM device. Restoration of the lumbar lordosis is the main aim.
Specialised physical therapy
In Germany, a standard treatment for both Scheuermann's disease and lumbar kyphosis is the Schroth method, a system of physical therapy for scoliosis and related spinal deformities. It involves lying supine, placing a pillow under the scapular region and posteriorly stretching the cervical spine.
Surgical treatment can be used in severe cases. In patients with progressive kyphotic deformity due to vertebral collapse, a procedure called a kyphoplasty may arrest the deformity and relieve the pain. Kyphoplasty is a minimally invasive procedure, requiring only a small opening in the skin. The main goal is to return the damaged vertebra as close as possible to its original height.
The risk of serious complications from spinal fusion surgery for kyphosis is estimated to be 5%, similar to the risks of surgery for scoliosis. Possible complications may be inflammation of the soft tissue or deep inflammatory processes, breathing impairments, bleeding, and nerve injuries. According to the latest evidence, the actual rate of complications may be substantially higher. Even among those who do not suffer serious complications, 5% of patients require re-operation within five years of the procedure, and in general it is not yet clear what to expect from spine surgery in the long-term. Taking into account that signs and symptoms of spinal deformity cannot be changed by surgical intervention, surgery remains to be a cosmetic indication. Unfortunately, the cosmetic effects of surgery are not necessarily stable. In case one decides to undergo surgery, a specialised centre should be preferred.
^Pfeifer M, Begerow B, Minne HW (2004). "Effects of a new spinal orthosis on posture, trunk strength, and quality of life in women with postmenopausal osteoporosis: a randomized trial". American journal of physical medicine & rehabilitation / Association of Academic Physiatrists83 (3): 177–86. doi:10.1097/01.PHM.0000113403.16617.93. PMID15043351.
^Lehnert-Schroth, Christa (2007). Three-Dimensional Treatment for Scoliosis: A Physiotherapeutic Method for Deformities of the Spine. (Palo Alto, CA: The Martindale Press): 185-187 and passim.