Abnormal forward bending of the spine is referred to as kyphosis. The normal spine, when viewed from behind, appears straight throughout its entire length. However, when one looks at the spine from the side, there are two visible curvatures. There is a gentle rounding of the upper back from the shoulders to the bottom of the ribcage known as thoracic kyphosis and an opposite curve in the lower back known as lumbar lordosis. These two opposite curvatures of the spine are necessary in the normal spine to balance the trunk and head over the pelvis.
A normal thoracic spine extends from the 1st to the 12th vertebra and should have a slight kyphosis ranging from 20o to 45o. When the “roundness” of the upper spine increases past 45o it is called “hyperkyphosis” or simply ‘kyphosis’. Kyphosis in the lower back can present as simply a loss of lordosis or a development of kyphosis.
The body much more poorly tolerates kyphosis than scoliosis. A moderate degree of kyphosis can cause much more back pain than scoliosis. A kyphosis > 90 degree can start stretching the spinal cord resulting in progressive paralysis. Therefore, kyphosis needs corrective surgery much more commonly than scoliosis.
Corrective surgery for kyphosis is usually performed from the middle of the back. The kyphosis is usually corrected using osteotomy of the spine like Smith Peterson Osteotomy, Ponte Osteotomy, Pedicle Subtraction Osteotomy or Vertebral Collumn Resection. The bend in the spine is then corrected using titanium screws and rods and the bones involved in the bend are then fused together so that the bend does not progress any further with growth.
The most common types of kyphosis in India are as follows:
- Congenital kyphosis – Some kids may be born with an anomaly in their spinal bones such that there is progressive bend in the spine with the growth of the kid. Such cases may be associated with Spinal Cord Malformations and always need an MRI Whole Spine to look at spinal cord anomalies. If the bend is progressive, then they almost always need surgery.
- Post-traumatic kyphosis – Old fractures that have not been managed appropriately can lead to a bend in the spine. These bends are usually non-progressive and may need surgery if they cause disabling back pain.
- Post tuberculosis kyphosis – Tuberculosis commonly affects the spinal bones. While TB heals it almost always leaves behind varying degrees of kyphosis. In children, this kyphosis can frequently become severe reaching > 90 degrees. When kyphosis exceeds 90 degrees it can start stretching the spinal cord resulting in paralysis. The best way of tackling this problem of post TB kyphosis is to prevent it from developing by recognizing it and operating upon TB spine early in the disease if progressive kyphosis is anticipated. Once already established, correction of post TB kyphosis is a fairly big operation. This usually involves an osteotomy (usually Pedicle Subtraction Osteotomy or Vertebral Column Resection) of the spine performed under neuromonitoring.
- Scheuermann’s kyphosis is the most classic form of hyperkyphosis and is the result of wedged vertebrae that develop during adolescence. This usually affects teenage boys with the deformity being noticed usually during their pubertal growth spurt. These boys should be encouraged not to gain weight and performing stretching exercises like hanging from an overhead monkey bar. Swimming and some yoga asanas (like Bhujangasana) are also beneficial. Most of these cases can be managed with exercises, but if the pain is disabling or if the deformity is very severe, then corrective surgery is offered.
- Ankylosing Spondylitis–Patients with Ankylosing spondylitis have a progressive tendency of the back to develop a hump (hindi – kubb). Ankylosing spondylitis frequently affects men between 20-40 years and is fairly common in India. Ankylosing spondylitis has a genetic predisposition and can run in families. Patients with ankylosing spondylitis with a severe bend (kyphosis) in the neck and back may seek the opinion of a spine surgeon for correction of their deformity. This is a major operation, but can be done safely by performing an osteotomy (usually Pedicle Subtraction Osteotomy) of the spine under neuromonitoring.
- Lumbar degenerative kyphosis (Adult Deformity / Adult Sagittal Imbalance / Fixed Sagittal Imbalance) – This type of kyphosis usually affects women > 60 years age. It is a result of extensive wear and tear in the spine as a result of aging. These patients may develop a stooping forward posture and find it difficult to stand up straight. This may be associated with pinching of the nerves (lumbar canal stenosis) and degenerative scoliosis. Degenerative scoliosis and lumbar degenerative kyphosis together form different spectrums of Adult Deformity or Adult Sagittal Imbalance. Lumbar degenerative kyphosis is often poorly tolerated, because of severe low back pain and nerve compression. If symptoms of the patient are very disabling, then a long posterior fusion down to the pelvis along with decompression will benefit these patients.
- Osteoporotic Kyphosis – Osteoporosis is very common in India and usually affects women > 65 and men > 70 years. Osteoporosis can result in a forward bend from collapse (wedging) of vertebrae and fracture of multiple vertebrae. Treatment of osteoporotic kyphosis is mainly medical management of osteoporosis to prevent further progression of kyphosis. Painful osteoporotic fractures may benefit from cement injection (Kyphoplasty / Vertebroplasty).