Lordosis, kyphosis, and scoliosis

Lordosis, kyphosis, and scoliosis refer to curvatures of the spine.

Lordosis refers to the normal inward curvatures of the spine at the cervical and lumbar regions, while kyphosis refers to the normal outward curvature of the spine specifically at the thoracic region.

These terms get used interchangeably with hyperlordosis and hyperkyphosis, which means that the curves look abnormally pronounced.

Finally there’s scoliosis which always refers to the abnormal sideways curves of the spine.

Now, the bony spine is made of vertebral bones, and there are intervertebral discs that sit between adjacent vertebrae.

The spine is made of 33 vertebrae, which can be divided into 5 regions.

The cervical region has 7 vertebrae, the thoracic region has 12 vertebrae, the lumbar region has 5 vertebrae, the sacral region has 5 vertebrae, and the small tail-like coccygeal region is made up of 4 fused vertebrae.

Normally, the cervical and the lumbar spines slightly curve inward.

This results from the fact that the intervertebral discs in these two regions are thicker anteriorly than posteriorly, which causes this part of the spine to lean forward.

On the other hand, the thoracic and the sacral spines are normally curved backward, which is normal kyphosis.

Lordosis and kyphosis are typically associated with underlying conditions.

For example, in osteoporosis the bones become porous and weak, and can develop compression fractures causing the bones to collapse a bit.

This can cause a spinal deformity and can also impinge on nearby nerves.

Misaligned vertebrae can also exert too much pressure on the intervertebral discs, causing them to degenerate.

Other conditions include spondylolisthesis, in which a vertebrae slips out of its normal position, or conditions like Ehlers-Danlos syndrome and Marfan syndrome, where bones and connective tissues overgrow, causing spinal instability.

Obesity can also put excess unbalanced weight on the spine causing it to deform.

Other causes include inflammation of the intervertebral discs, which can happen from overuse due to a sports injury or lifting weights in an inappropriate way.

Lordosis typically affects the lumbar region, and can specifically result from the trunk flexors and the hip extensors becoming too weak to balance the action of trunk extensors and hip flexors.

When that happens, the lumbar spine gets over-extended, causing it to progressively curve inwards, causing lumbar lordosis.

Lordosis results in an incurved back in the cervical or lumbar spine.

Kyphosis mainly affects the thoracic spine.

It usually occurs when the front of the thoracic vertebrae gets deformed or crushed, causing this part of the spine to excessively bend forward.

Kyphosis typically results in a rounded back in the thoracic spine, which looks like a hump in the upper back.