Scoliosis on MRI & X-ray: Imaging Findings

The Cobb angle is measured on a full-length standing posteroanterior (PA) radiograph by drawing lines along the endplates of the most tilted vertebrae at the upper and lower ends of the curve — the angle between these lines (or their perpendiculars) is the Cobb angle. Curves less than 10° are considered normal spinal variation; 10–24° are monitored with serial radiographs every 6–12 months in skeletally immature patients (Risser 0–2). Curves of 25–40° with documented progression of greater than 5° are managed with thoracolumbosacral orthosis (TLSO) bracing to prevent further progression until skeletal maturity. Curves exceeding 45–50° in adolescents, or greater than 50° in adults with pain or neurological compromise, are considered for surgical correction with instrumented spinal fusion. EOS low-dose biplanar imaging minimizes cumulative radiation in young patients requiring serial monitoring.

Standing radiographs define curve magnitude and skeletal maturity (Risser sign of iliac apophysis ossification), but MRI is indicated when curve patterns are atypical or neurological symptoms are present. Left thoracic curves in adolescents and rapidly progressive curves are associated with underlying spinal cord abnormalities — Chiari malformation type I, syringomyelia, tethered cord, or spinal cord tumor — that can drive curve progression and must be excluded before bracing or surgery. In adult degenerative scoliosis, MRI assesses the degree of disc degeneration (Pfirrmann grading), facet arthropathy, Modic endplate changes, foraminal and central canal stenosis, and coronal imbalance — all critical for surgical planning including the need for interbody reconstruction and extent of instrumentation.

Adolescent idiopathic scoliosis (AIS) develops during the growth spurt (ages 10–16), has no identifiable cause, and is most common in girls. It is typically asymptomatic initially, detected on school screening or by parental observation. The natural history depends on curve magnitude at skeletal maturity — curves below 30° at maturity rarely progress, while curves above 50° tend to progress at approximately 1° per year throughout life. Adult de novo scoliosis develops after skeletal maturity due to asymmetric degenerative disc disease and facet arthropathy, most often in women after age 50 and frequently presenting with back pain, lateral listhesis, and neurogenic claudication. Distinguishing the two is important because treatment goals differ: AIS aims to prevent progression and cosmetic deformity, whereas adult scoliosis management primarily targets pain and neurological function.