Scoliosis is an abnormal side-to-side curvature of the spine, where the vertebral column deviates into a “C” or “S” shape. A diagnosis is typically made when this lateral curve reaches 10 degrees or more. Since the condition is most often identified during adolescence, a primary concern is whether the spinal curve will continue to worsen once the body has finished growing. This article investigates how skeletal development influences the stability of the curvature into adulthood.
The Role of Growth in Curve Progression
The largest driver of scoliosis progression is the rapid increase in height during adolescence. This period of accelerated bone elongation creates mechanical forces on the spine, which can cause an existing curve to worsen significantly. Spinal growth is not symmetrical in a scoliotic spine, meaning the uneven pressure accelerates the curve’s deviation.
This progression risk persists throughout the adolescent growth spurt, requiring frequent monitoring. Physicians assess the patient’s remaining growth potential using tools that measure skeletal maturity. A common method involves evaluating the Risser sign, a grading system that tracks the ossification of the iliac crest in the pelvis.
A lower Risser grade indicates significant growth remaining and a higher risk for rapid curve worsening. Conversely, a higher Risser grade suggests that the growth plates are closing, and the period of rapid spinal change is nearing an end. The severity of the curve at the beginning of this growth phase is a strong indicator of future progression risk.
Curve Stabilization After Skeletal Maturity
For the majority of people with adolescent idiopathic scoliosis, the curve stops progressing after skeletal maturity. Once an individual reaches skeletal maturity, typically indicated by a Risser sign of 4 or 5, the acceleration of the curve almost always slows down or halts entirely. The risk of the curve worsening significantly drops once the growth plates have fused.
The spinal column becomes mechanically stable when the bones are fully developed and no longer rapidly elongating. This stabilization is the natural history for most cases of adolescent scoliosis that did not require surgical intervention. Patients who reach maturity with a minor or moderate curve often find their condition remains stable for decades.
Predicting Continued Progression in Adulthood
While rapid progression stops after growth, a small, slow progression can occur in adulthood, particularly for those with larger curves. The most reliable predictor of continued progression is the magnitude of the curve at the time of skeletal maturity. Curves measuring over 40 to 50 degrees are at the highest risk for gradual worsening throughout adult life.
This slow progression typically occurs at a rate of 1 to 2 degrees per year. The location of the curve is also a factor, with thoracolumbar and lumbar curves tending to progress more frequently than those located purely in the thoracic spine. Specific patterns, such as the double major curve, may also influence long-term stability.
Adult progression is often compounded by the natural aging process of the spine, known as degenerative changes. Degeneration of the intervertebral discs, osteoporosis, and loss of muscle support contribute to the slow deformation of the spine. These factors introduce asymmetry and instability, leading to a gradual increase in curve magnitude long after skeletal growth has ceased.
Long-Term Management and Monitoring
For adults with stable or slowly progressing scoliosis, long-term management focuses on symptom control and maintaining spinal function. Monitoring involves periodic check-ups, often including X-rays every few years, to track changes in curve magnitude and spinal balance. This schedule may be more frequent if risk factors for progression are present.
Non-surgical approaches are the foundation of adult management, centering on physical therapy and core strengthening. Targeted exercises improve spinal stability, flexibility, and muscle balance, mitigating pain associated with altered spinal biomechanics. Pain management strategies may include over-the-counter pain relievers or steroid injections for localized discomfort.
Surgical intervention is reserved for cases where the curve progresses rapidly, causes severe, unmanageable pain, or leads to significant functional impairment. This threshold is often reached when the curve magnitude exceeds 50 or 60 degrees in the skeletally mature adult. Surgery aims to stabilize the spine, correct the deformity, and alleviate pressure on nerves.