Scoliosis is an abnormal lateral curvature of the spine, often associated with adolescence, but it remains a significant concern in adulthood. For individuals with a pre-existing curve or those who develop one later in life, the curve often progresses. This adult progression is a common clinical reality, even after skeletal growth has stopped. These changes are primarily influenced by mechanical wear and tear on the spine over decades.
Understanding Adult Scoliosis Progression
Adult scoliosis is broadly categorized into two primary types. The first involves the continued worsening of a curve that originated in youth, most commonly Adolescent Idiopathic Scoliosis (AIS). These curves, stable during non-growing years, begin to progress due to the degenerative changes that affect all aging spines.
The second category is known as de novo or degenerative scoliosis. This means a new curve develops in a previously straight spine, typically appearing after age 40. It results from asymmetric degeneration of the intervertebral discs and facet joints. As one side of a disc wears down more quickly, the vertebrae tilt, creating a new spinal curvature over time.
Progression mechanisms differ: AIS progression is superimposed on an existing structural deformity. De novo scoliosis is purely a result of age-related asymmetric collapse in the lumbar or thoracolumbar regions. Both ultimately lead to spinal imbalance and potential symptoms.
Key Factors Influencing Worsening Curves
The most powerful predictor of whether a pre-existing curve will progress in adulthood is its magnitude at skeletal maturity. Curves measuring 30 degrees or more are significantly more likely to worsen over a lifetime. Curves exceeding 50 degrees carry a near certainty of continued progression, usually at a slow rate of around 0.5 to 3.0 degrees per year.
The location of the curve is also a factor. Curves in the lumbar (lower back) and thoracolumbar regions tend to progress more frequently than those confined to the thoracic (mid-back) spine. The lumbar spine is subject to greater biomechanical stress from bearing body weight, which accelerates the degenerative process. The thoracic spine gains stability from the rib cage, offering protection against rapid change.
Age-related changes in spinal components are the underlying mechanisms of adult progression. Degenerative disc disease and facet joint arthritis cause the spine to lose height and stability, leading to an asymmetrical collapse of the vertebral column. This creates a cycle where the instability drives further degeneration, causing the curve to worsen.
Osteoporosis, the weakening of bone density, is another contributor. When the vertebrae lose density, they become less able to withstand the asymmetrical forces exerted by the curve. This weakening can accelerate the rate of progression and lead to micro-fractures or wedging of the vertebrae, further destabilizing the spine.
How Progression is Measured
Clinicians track scoliosis progression using full-length standing X-rays of the entire spine. The standard method for quantifying the curve is the Cobb angle, which measures the greatest angle of tilt between the most tilted vertebrae at the top and bottom of the curve.
Progression in an adult is defined as an increase of 5 degrees or more in the Cobb angle between evaluations. Clinicians look for consistent, repeated increases over multiple visits to confirm a true worsening of the curve, accounting for inherent measurement variability.
Imaging studies also assess the overall balance of the spine, known as sagittal alignment. This evaluates whether the head and torso are positioned correctly over the pelvis. Sagittal alignment is often a better indicator of functional capacity and pain than the Cobb angle alone. Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans may also be used to evaluate the health of the intervertebral discs and check for nerve compression.
Managing Progressive Adult Scoliosis
When progression is confirmed and symptoms worsen, management strategies focus on controlling pain, improving function, and stabilizing the spine. Non-surgical options are the first line of defense for most adults.
Non-Surgical Management
Physical therapy often incorporates scoliosis-specific exercises that strengthen core muscles to improve posture and spinal support. Pain management uses anti-inflammatory medications or epidural steroid injections to alleviate nerve root irritation. Bracing may be used in adults, not to correct the structural curve, but to provide external support for the torso. This external support can help reduce pain and improve stability during daily activities.
Surgical Intervention
Surgical intervention is reserved for cases where non-surgical methods fail to control intractable pain, or when the curve progresses to a severe magnitude, often exceeding 50 degrees. Surgery is also considered if the deformity causes significant functional impairment or neurological deficits, such as weakness or numbness in the legs. The primary goal of surgery is to stabilize the spine and decompress any pinched nerves, usually through a spinal fusion procedure.