Degenerative scoliosis is a spinal curvature that develops in adulthood, primarily due to the natural aging process. Unlike childhood scoliosis, which often has no clear cause, this adult-onset condition is directly linked to the wear and tear of spinal structures over time. It results in a sideways curve, typically in the lower back, which can progress gradually.
The Aging Spine
The spinal column undergoes age-related changes as individuals grow older. Intervertebral discs, which cushion vertebrae, lose hydration and elasticity over time. This reduction in water content decreases disc height, making the spine less flexible and less capable of absorbing shock. Facet joints, small joints connecting the vertebrae, can develop arthritis as their protective cartilage breaks down. Spinal ligaments, which provide stability, can also thicken or become lax, further affecting spinal integrity.
Core Degenerative Changes
Degenerative scoliosis is driven by the asymmetrical degeneration of spinal components. Uneven collapse or deterioration of intervertebral discs on one side is a key factor. This asymmetrical disc degeneration leads to an imbalance, causing the spine to lean or shift sideways.
Arthritis in the facet joints can also occur unevenly. This uneven facet joint degeneration contributes to instability and a sideways shift of vertebral segments. Weakening or thickening of spinal ligaments can further destabilize the spine, contributing to the abnormal curvature. These combined, uneven changes cause the spinal column to progressively curve to one side.
Contributing Risk Factors
Several factors do not directly cause spinal degeneration but can accelerate its progression or increase the likelihood of developing degenerative scoliosis. A genetic predisposition can play a role, as individuals with a family history of scoliosis may have a higher risk.
Osteoporosis, characterized by weakened and porous bones, can make the spine more susceptible to collapse and curvature. Weakened spinal bones are more prone to compression fractures, which can lead to changes in spinal alignment.
Previous spinal injuries or surgeries can alter spinal mechanics and increase the risk of degenerative changes in adjacent segments. Lifestyle factors such as prolonged poor posture, a sedentary routine, and obesity can add stress to the spine, contributing to accelerated disc degeneration.
How Spinal Curvature Develops
The visible sideways curvature and rotation of the spine in degenerative scoliosis result from the combined effects of core degenerative changes and contributing risk factors. Asymmetrical degeneration of discs and facet joints creates an uneven distribution of weight and stress across the spinal column. This imbalance causes the vertebrae to tilt and rotate, leading to the characteristic C-shaped curve, most commonly in the lower back. The body attempts to compensate for this imbalance by shifting other parts of the spine or pelvis, which can lead to further curvature or changes in overall posture. This progressive process eventually manifests as the spinal deformity.