Three-dimensional lateral curvature of the spine measuring ≥10 degrees by the Cobb method.
Also known as: AIS, adolescent idiopathic scoliosis, scoliosis, spinal curvature
Overview
A three-dimensional structural deformity of the spine with lateral curvature measuring at least 10 degrees by the Cobb method, accompanied by vertebral rotation. Idiopathic scoliosis is diagnosed by exclusion and classified by age at onset — infantile (<3 years), juvenile (3-10 years), and adolescent (≥10 years). Adolescent idiopathic scoliosis (AIS) is by far the most common.
Epidemiology
Prevalence approximately 2-4 percent in adolescents for curves ≥10 degrees, dropping to 0.3-0.5 percent for curves ≥30 degrees. Female-to-male ratio is approximately 1:1 for small curves but 8:1 for curves requiring treatment.
🔒 Free preview limit reached
Keep reading — start your free trial
You've read your 2 free diagnosis previews. Create your free account to unlock the full Scoliosis (Adolescent Idiopathic) outline — plus all 514 diagnoses, 3,500+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.
Female sex (particularly for progression of curve)
Family history
Skeletal immaturity (Risser 0-1) and pre-menarche status at diagnosis
Larger curve magnitude at presentation
Curve apex at thoracic level
Pathophysiology
Cause remains unknown — multifactorial inheritance involving genetic, neuromuscular, hormonal, biomechanical, and connective tissue factors. Asymmetric growth of the vertebral bodies and ribs combined with rotation produces the characteristic deformity, with concavity, vertebral wedging, and rib hump on the convex side.
Clinical presentation
Symptoms
Usually asymptomatic; identified on school screening, parent observation, or routine well-child exam
Postural scoliosis — Functional curve corrects with forward bending; no rotation
Leg length discrepancy — Apparent scoliosis on standing exam; corrects with seated examination or block
Diagnostic workup
Diagnostic criteria
Diagnosis: lateral curvature ≥10 degrees by Cobb method. Risser staging (0-5) and triradiate cartilage status assess remaining growth potential. Treatment thresholds are based on Cobb angle and skeletal maturity (see treatment).
Labs
None for routine idiopathic scoliosis
Imaging
Standing PA and lateral full-length spine radiographs are the standard
Measure Cobb angle between the most tilted vertebrae at the upper and lower ends of the curve
Assess skeletal maturity (Risser 0-5) using iliac apophysis ossification
MRI of the entire spine for atypical features: left thoracic curve, rapid progression, painful curve, abnormal neurologic exam, or onset before age 10
Diagnostic algorithm
Cobb Angle
Skeletal Maturity
Management
10-25 degrees
Any
Observation; serial radiographs
25-45 degrees
Skeletally immature (Risser 0-2)
TLSO brace ≥18 h/day
25-45 degrees
Skeletally mature
Observation
>45-50 degrees
Skeletally immature
Posterior spinal fusion
>50 degrees
Skeletally mature
Posterior spinal fusion (continues to progress)
Management of adolescent idiopathic scoliosis by Cobb angle and skeletal maturity.
Treatment
First-line
Observation with serial clinical examination and radiographs every 4-6 months for curves 10-25 degrees in skeletally immature patients
Stretching, postural exercises, and physical therapy do not prevent progression but help with comfort and function
Scoliosis-specific exercises (Schroth method) have modest supportive evidence for small to moderate curves
Second-line / adjunct
Bracing for curves 25-45 degrees in skeletally immature patients (Risser 0-2) — modern thoracolumbosacral orthoses (TLSO) such as Boston brace, Wilmington brace, or Providence/Charleston bending brace at night
Bracing efficacy established by the BrAIST trial — 18 hours per day of wear reduces progression to surgical thresholds compared to observation
Posterior spinal fusion with instrumentation for curves >45-50 degrees in skeletally immature patients or >50 degrees in skeletally mature patients
Anterior fusion or vertebral body tethering in selected cases
Complications
Progression of curve magnitude through skeletal maturity and continued slow progression of large curves in adulthood
Adolescent idiopathic scoliosis is diagnosed by exclusion — atypical features (early onset, left thoracic curve, neurologic abnormalities, painful curve) require MRI to evaluate for intraspinal pathology.
Bracing is effective for skeletally immature patients with curves 25-45 degrees; the BrAIST trial established the dose-response relationship.
Curves >50 degrees at skeletal maturity continue to progress at approximately 0.5-1 degree per year into adulthood.
School screening with scoliometer (>7 degrees) helps prioritize radiographic evaluation.
References
BrAIST — Weinstein SL et al., Effects of Bracing in Adolescents with Idiopathic Scoliosis (NEJM 2013)
SRS — Scoliosis Research Society clinical guidance on adolescent idiopathic scoliosis
POSNA — Pediatric Orthopaedic Society of North America clinical resources on scoliosis
Practice Musculoskeletal questions on FirstPassPA
Turn this outline into retention. 3,500+ board-style questions with an AI tutor that explains every answer — free to start, no card required.
Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants.