Lumbar hyperlordosis, also known as swayback, occurs due to hyper-flexibility of the joints of the back or weak psoas muscles, which causes an excessive forwards curvature of the spine towards the front of the body.
In the human spine, there are 4 main curvatures: the cervical (neck), thoracic (chest/trunk), lumbar, and pelvic. In the human spine, the spine curves towards the front of the body, beginning at the base of the neck. Then the spine curves backwards, toward the surface of the back in the thoracic spine. The curve of the spine curves forwards (anteriorly) in the lumbar spine (lower back) one more time, before curving backwards (posteriorly) one more time in the pelvic spine. The pelvic spine is composed of the sacrum and coccyx.
In the human spine, the Cervical and Lumbar curves are also known as the lordotic (lordosis) curves. These curves are also described as being convex anteriorly and concave posteriorly. There curves are also known as secondary curves, because they only develop after we are born. In the human spine, a cervical lordosis curve is within the normal range when it is between 20-40 degrees, and the lumbar lordosis curve is within normal range when it is between 40-60 degrees. Angles of curvature beyond the normal range may be diagnosed as pathological. When this pathologically excessive curve occurs in the lumbar spine, the condition is known as lumbar hyperlordosis, or Swayback.
The thoracic and pelvic curves are also known as the kyphotic curves. The kyphotic curves are concave anteriorly and convex posteriorly. These curves are known as primary curves because they are present at birth. The normal range of the kyphotic curve in the cervical spine is between 20-40 degrees. In the pelvic spine, most anterior edge of the sacrum coccyx should be vertically parallel to the most anterior position in the thoracic spine, for the two structures to be considered in normal alignment.
Ok, now back to the cervical and lumbar spine. Any angle of curvature beyond 60 degrees may be clinically described as lumbar lordosis, or hyperlordosis.
In the condition of lumbar hyperlordosis, the spine has an exaggerated anterior curvature (towards the front of the body), which may occur for several reasons. One sign of hyperlordosis is a protruding abdomen, which the doctor may notice upon a physical examination. A protruding abdomen may indicate weak abdominal muscles, which causes them to fail in their purpose in holding the spine within a healthy range of alignment. The lateral curvature of the spine serves the purpose of shock absorption against ground impact as we stand, walk and hit the group. Imagine the impact of landing from a 5 foot jump without bending your knees and hips - how it would hurt your joints. This same concept could be applied to how the joints of the spine would be affected by walking and landing if the spine were straight.
Within the normal range of the lordotic curvature, the joints and soft tissues of the spine remain adequately protected. Beyond the range of 60 degrees, the condition of hyperlordosis exists, which may cause great stress on the intervertebral discs, ligaments, and other soft tissues.
Around the level of the lumbar spine (lower back), there are points of attachment or insertion on all sides of the vertebrae, either for the purposes of performing movements, or simply to hold the spine in the correct position while at rest. Due to conditions such as muscle tension or muscle weakness, however, the spine may be pulled out of its normal alignment.
This condition is common in athletes such as dancers, who put a lot of stress on the ligaments and weight-bearing portions of their lumbar spine.
Other sports or lifting factors that may make people more prone to this type of condition include heavy lifting of weights and object while having weak psoas muscles. Heavy lifting on weak psoas muscles causes forces athletes and others to use their backs rather than their hips while they elevate their objects and bodies.
Lumbar hyperlordosis may be a factor in the cause of lower back pain.