Scoliosis, defined by a sideways curvature of the spine, is often associated with adolescence, but it can and often does progress in adulthood. This progression potentially leads to increased pain and functional decline. This spinal deformity affects a significant portion of the aging population, with prevalence estimates reaching up to 68% in individuals over 60 years old. Understanding the mechanisms that cause a curve to worsen after the growth period is key for effective management.
Differentiating Adult Scoliosis Types
The term “adult scoliosis” is broadly categorized into two distinct types, each having a different origin and progression mechanism.
The first type is Adult Idiopathic Scoliosis, which is the progression of a curve that began in childhood or adolescence. This form represents a curvature that was present but may have been stable or unnoticed for many years after skeletal maturity.
The second, and increasingly common, type is De Novo Degenerative Scoliosis. This curve develops anew in a previously straight spine, typically after the age of 40 or 50. This form is directly linked to age-related wear and tear on the spinal structures. As the intervertebral discs and facet joints degenerate asymmetrically, the spine loses stability and begins to tilt and curve. Both types involve superimposed degenerative changes, but the underlying cause—a pre-existing structural curve versus new-onset collapse—remains the primary differentiator.
Key Factors Driving Curve Progression
Several factors contribute to the worsening of an adult scoliotic curve over time. The initial magnitude of the curve is a major predictor of future progression risk. Curves greater than 30 degrees at skeletal maturity are more likely to progress than smaller curves, and those exceeding 50 degrees have a high likelihood of continued change.
The anatomical location also plays a role. Curves in the lumbar (lower back) and thoracolumbar regions tend to be less stable and progress more often than those confined to the thoracic spine, which is stabilized by the rib cage. The asymmetric breakdown of discs and joints creates segmental instability, allowing gravity and daily biomechanical stresses to exacerbate the lateral curvature. Progression is often slow, advancing 0.5 to 1 degree per year, though degenerative curves can occasionally worsen more rapidly, sometimes 3 to 4 degrees annually.
Bone health is a key driver of progression, particularly in women due to post-menopausal osteoporosis. Reduced bone mineral density weakens the vertebral bodies, making them susceptible to collapse and asymmetric loading. This accelerated degeneration, combined with a loss of spinal balance, creates a cycle where instability leads to further curvature and structural compromise.
Recognising the Symptoms of Progression
A worsening curve shifts the focus from cosmetic deformity to functional and symptomatic issues. The most common indicator of progression is the onset or increase of chronic back pain, which can be localized to the curve or radiate into the legs due to nerve compression. This nerve irritation, known as radiculopathy, causes sensations like tingling, numbness, or shooting pain.
Changes in posture and overall body alignment become noticeable, such as a visible truncal shift, uneven hips, or pitching forward, a phenomenon called sagittal imbalance. Functional limitations also appear, including muscle fatigue or difficulty standing comfortably for extended periods. In severe cases, large thoracolumbar curves can impact internal organ function, leading to symptoms like shortness of breath or the sensation of premature fullness while eating.
Strategies for Monitoring and Management
Adults with scoliosis require a proactive approach combining regular monitoring with conservative and, when necessary, surgical interventions. For patients with a stable or mild curve, periodic checkups are recommended. These often include standing X-rays taken every few years to accurately measure the Cobb angle and track changes. This monitoring ensures that any significant progression is caught early.
Non-surgical management focuses on alleviating symptoms and stabilizing the spine through physical therapy. Specific exercises strengthen the core muscles, which act as a natural brace, improving posture and managing muscle imbalances. Pain management strategies often include anti-inflammatory medications or targeted epidural injections to address nerve root irritation and inflammation associated with degenerative changes.
Surgical intervention is reserved for cases where the curve has progressed significantly, causing intractable pain unresponsive to conservative treatments, or when there is a clear neurological deficit like leg weakness. Surgeons generally consider stabilization procedures for curves exceeding 40 to 50 degrees, especially if associated with severe spinal imbalance or nerve function compromise. The decision to proceed with surgery is highly individualized, balancing the risks of the procedure against the patient’s quality of life and functional decline.