Kyphosis is a forward bending of the spine which produces a roundback curvature.
Looking at the spine from the side, the spine has two 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 (sway back). The two opposite curvatures of the spine work together to balance the trunk and head over the pelvis.
A normal thoracic spine extends from the 1st to the 12th vertebra (Figure 1) and with a slight kyphosis ranging from 20° to 45°. When the "roundness" of the upper spine increases past 45° it is called "hyperkyphosis".
Postural kyphosis is not rigid but other types of kyphosis described in this section are and not uncommonly, kyphosis occurs together with scoliosis (side-to-side spine curvature) or lordosis (swayback).
Types of Kyphosis
Kyphosis can result as a malformation in utero, or can develop during growth and aging. The three primary types of kyphosis are: