The human spine is made of small bones called vertebrae, which are stacked together with discs, one on top of the other. A healthy spine will have a gentle curve when looked from the side, which is quite natural. In fact, the curve of the spine helps it to absorb stress and shock from gravity and body movement.
Spine curvature disorders refer to the disorders caused by dislocation, degeneration or injury to any of the 33 vertebrae that constitute the vertebral column. These are divided into – Cervical (top 7 vertebrae), Thoracic (next 12 vertebrae), Lumbar (last 5 vertebrae) and Sacrococcygeal (9 fused vertebrae forming the sacrum and coccyx) regions.
The spine should run straight down the middle of the back and if there are any abnormalities, it will get misaligned at some areas. This condition is called spine curvature disorder.
There are three main types of spine curvature disorders, including:
It is also called “sway back” condition and is characterized by an extreme inward curvature of the spine. Lordosis can affect the lower back and neck. Extreme cases of Lordosis are observed in adolescence due to some existing diseases or poor postures for prolonged period. The vertebral and spinal muscles are severely affected in such cases. Mild cases of Lordosis in the lumbar and cervical regions are considered normal.
Lordosis has the following subtypes:
- Cervical Lordosis: Inward curvature of the cervical portion of the spine is observed especially in the neck region.
- Thoracic Lordosis: Inward curvature of the thoracic portion of the spine occurs.
- Lumbar Lordosis: In this condition, there is abnormal inward curvature of the lumbar (lower) portion of the spine
- Congenital Lordosis: It is caused due to inward spine curvatures present since birth.
Kyphosis refers to the abnormal curvature or bowing of the back due to the outward curvature of the lumbar spine. Kyphosis is characterized by an abnormally rounded upper back (more than 50 degrees of curvature). It can be an outcome of different conditions such as arthritis of spine (damage of vertebra), osteoporosis of spine (thinning of vertebral bones) and diseases like spina bifida or myelomeningocele.
It has the following subtypes:
- Postural Kyphosis: It is a very common form of Kyphosis and is called Hyperkyphosis or Dowager’s Hump (in aged people). It is characterized by abnormal slouching.
- Scheuermann’s Kyphosis: It is also called Adolescent Kyphosis and is more commonly observed in adolescents and teenagers. In this condition, a series of vertebral bones are wedged together, causing deformity and abnormal curvature of the spine.
- Nutritional Kyphosis: It is mainly observed in children suffering from rickets and is caused due to Vitamin D deficiency.
- Post-traumatic Kyphosis: It is an outcome of spinal fractures and injuries. (e) Congenital Kyphosis: It occurs due to malformed bones during early stages of fetal development. It results in major birth defects due to spinal deformities.
Scoliosis is a collective term for deformities of the spine and rib cage. It is commonly observed in the thoracolumbar area (portion between thoracic and lumbar regions). But it may also develop only in the thoracic region (upper back) and lumbar region (lower back). Scoliosis may develop as a single C-shaped curve, an S-shaped curve (consisting of a primary curve and a compensating or secondary curve), forming a three dimensional deformity. Scoliosis may be categorized into the following types based on anatomy and position.
Structural Scoliosis: This condition is characterized by abnormal curvature, rotation and twisting of the spine. Due to this, one half of the rib cage is pushed forward (creating large gaps between the ribs) and another half is pushed inward (causing compression of the ribs). The shoulder blade juts out causing differences in levels of the shoulders. Structural scoliosis has the following subtypes-
- Idiopathic scoliosis: Origin or cause of this type of scoliosis is not known. 8-10 cases of scoliosis are idiopathic in nature.
- Neuromuscular scoliosis: It is mainly observed in cases of muscular dystrophy and neurofibromatosis. The abnormal curvature in this condition is an outcome of disorders of the posterior muscles and nerves. 1 out of 10 cases of scoliosis belongs to this category.
- Osteopathic scoliosis: It results due to some major bone defect(s).
- Congenital scoliosis: This type of scoliosis occurs due to abnormal spine growth of the fetus in the womb. 1 out of 10 cases of this category is reported.
Functional scoliosis: It is also called Non-structural or Postural Scoliosis. In this case, the spine curvature is actually normal but looks curved due to other factors. It occurs due to non-anatomical defects of the spine such as a difference in leg length, poor postures, muscle spasms or spinal injuries.
Thoracic scoliosis: It is caused due to abnormal curvature of the upper portion of the spine.
Lumbar scoliosis: It is caused due to abnormal curvature in the lower portion of the spine.
Fixed scoliosis: It occurs due to infections of the spine or presence of spine tumors. It is characterized by visible deformities of the bone and back.
Non-fixed scoliosis: It is a secondary form of scoliosis and occurs due to paralysis of back muscles, misaligned hip, spinal injuries, and arthritis. This type of scoliosis is curable if the causative factors are eliminated.
There are a number of health problems that may cause the spine to curve more than normal or be misaligned.
Causes of lordosis includes the following:
- Achondroplasia. A disorder in which bones do not grow normally, resulting in the short stature associated with dwarfism
- Spondylolisthesis. A condition in which a vertebrae, usually in the lower back, slips forward
- Osteoporosis, a condition in which vertebrae become fragile and can be easily broken (compression fractures)
- Obesity or being extremely overweight
- Kyphosis. A condition marked by an abnormally rounded upper back
- Discitis. Inflammation of the disc space between the bones of the spine most often caused by infection
- Benign (harmless) juvenile lordosis
Causes of kyphosis includes the following:
- Abnormal vertebrae development in utero (congenital kyphosis)
- Poor posture or slouching (postural kyphosis)
- Scheuermann’s disease, a condition that causes vertebrae to be misshaped (Scheuermann’s kyphosis)
- Arthritis, osteoporosis
- Spina bifida, a birth defect in which the spinal column of the fetus does not close completely during development inside the womb
- Spine infections, spine tumors
It is not known what causes the most common type of scoliosis seen in adolescents. However, scoliosis tends to run in families. A disease, injury, infection, or birth defect could be to blame.