Scoliosis is a medical condition involving an abnormal, sideways curvature of the spine, often taking on an “S” or “C” shape when viewed from the back. While frequently associated with the rapid growth of adolescence, the condition represents a significant health concern for many adults. The presence of a spinal curve can lead to issues ranging from chronic pain to functional limitations.
Adult Scoliosis: Defining the Condition and Its Prevalence
Adult scoliosis is defined as a structural spinal curvature measuring 10 degrees or more in a skeletally mature individual. This structural curve involves the rotation of the vertebrae, differentiating it from a non-structural or postural curve that straightens with position changes. The true prevalence of adult scoliosis is far greater than generally realized, particularly among older adults.
Estimates vary widely, but adult scoliosis is a common finding in the aging spine. Studies show the condition may affect approximately 8.3% of the general adult population aged 25 to 74 years. The incidence increases dramatically with age; the prevalence in individuals over 60 years old ranges from about 36% to over 60% in some reports. Females also have a higher prevalence of scoliosis compared to males, sometimes nearly twice as high.
Understanding the Causes: Differentiating Adult Onset from Progression
Adult scoliosis arises from two distinct mechanisms: a progression of a pre-existing curve or the de novo onset of a new curve. The first type, the progression of Adolescent Idiopathic Scoliosis (AIS), occurs when a curve established during youth continues to worsen into adulthood.
Progression in AIS is generally slow after skeletal maturity, often less than two degrees per year, but it can accelerate due to factors like osteoporosis or continued degeneration of the spinal discs. This type typically involves an “S” shape curve that includes the thoracic (mid-back) spine.
The second mechanism, known as de novo degenerative scoliosis, describes a curve that develops anew in a previously straight adult spine. This is the most common form in older adults, typically appearing after age 40 or 50, driven by asymmetric aging of the spinal structures. The intervertebral discs lose height and elasticity unevenly, while facet joint arthritis and ligament laxity further destabilize the spine. This degenerative process causes the vertebrae to tilt and shift, leading to the formation of a lateral curve, most often in the lumbar (lower) spine.
Signs, Symptoms, and Quality of Life Impact
While adolescent scoliosis is often painless, adult scoliosis frequently causes chronic discomfort and physical limitations. The most common complaint is chronic lower back pain, resulting from the asymmetric loading and instability of the spine. This pain can be localized directly over the curve or may radiate outward.
The degenerative nature of adult scoliosis often leads to nerve compression, known as radiculopathy, causing pain, numbness, or tingling that travels down into the legs. The spinal curvature can also cause noticeable postural changes, such as an uneven waistline, hips, or shoulders, and a feeling of imbalance. Difficulty standing upright for long periods is a frequent symptom, as the body’s center of gravity shifts, requiring greater effort to maintain posture.
The Diagnostic Process
Diagnosing adult scoliosis begins with a detailed medical history and a physical examination to identify visible asymmetries and assess gait and posture. The physical exam helps the physician understand the patient’s symptoms and functional limitations. Imaging is necessary to confirm the diagnosis and quantify the severity of the curve.
The standard imaging tool is a standing, full-length X-ray of the entire spine. This image allows the physician to measure the curve using the Cobb angle method, the universally accepted standard for quantifying scoliosis severity. The Cobb angle is determined by drawing lines along the most-tilted vertebrae at the top and bottom of the curve, defining the degree of curvature.
For more complex cases, especially those with nerve-related symptoms, additional imaging like Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans may be used. These scans provide a detailed view of the soft tissues, allowing for the identification of underlying issues such as spinal stenosis, disc herniation, or nerve root compression that may be contributing to the patient’s pain.