At what degree of curvature is treatment for scoliosis recommended?

Treatment Thresholds for Scoliosis

Treatment for scoliosis is recommended when curves exceed 20-25 degrees in skeletally immature patients (requiring bracing), and surgical intervention is indicated when curves exceed 45-50 degrees. 1, 2, 3

Observation Only (No Active Treatment)

• Curves less than 20 degrees require observation with periodic radiographic monitoring 4, 5
• For adolescents at Risser stages 0-3, limit spine radiographs to once every 12 months 2
• For Risser stages 4-5, radiographs every 18 months are sufficient 2
• Skeletally immature patients with curves under 20 degrees have less than 30% risk of progression 2

Bracing (Conservative Treatment)

• Curves between 20-45 degrees in skeletally immature patients warrant bracing to prevent progression 4, 5
• Curves above 20 degrees requiring conservative treatment occur in 0.3-0.5% of the growing population 4
• Bracing aims to prevent curves from reaching surgical thresholds during remaining growth 4

Surgical Intervention Thresholds

The critical decision point is 45-50 degrees, with the following specific indications:

Primary Surgical Indications:

• Curves exceeding 50 degrees in skeletally mature patients require surgical intervention due to continued progression risk of approximately 1 degree per year even after skeletal maturity 1, 2, 3
• Curves exceeding 40-50 degrees with remaining growth potential warrant surgery to prevent further progression 1, 3, 5
• Surgery is generally recommended for curves exceeding 45 degrees based on three key principles: curves larger than 50 degrees progress after skeletal maturity, greater magnitude curves cause pulmonary function loss, and larger curves become more difficult to treat surgically 3

Additional Surgical Considerations:

• Documented curve progression despite skeletal maturity is an indication for surgery 2
• Significant pain unresponsive to conservative measures may warrant surgical intervention 2
• Significant cosmetic concerns affecting quality of life can be considered, though this is a secondary indication 2

Critical Risk Factors for Progression

When deciding on treatment intensity, assess these progression risk factors:

• Age and skeletal maturity: Younger age and Risser stage IV are significantly associated with curve progression (p=0.004 and p=0.014 respectively) 6
• Baseline curve magnitude: In patients with curves between 40-50 degrees at Risser IV-V, 39.2% experienced significant progression over 5 years, with 24.7% reaching ≥50 degrees 6
• Curve location: Thoracic curves >50 degrees may progress at 1 degree per year after skeletal maturity 2, 7
• Growth potential: Skeletally immature individuals with curves >20 degrees have progression likelihood exceeding 70% 2

Pre-Surgical Evaluation Requirements

Before proceeding with surgery, obtain MRI evaluation to rule out neural axis abnormalities, particularly if any of these risk factors are present 2:

• Left thoracic curve pattern
• Short segment curve
• Absence of apical segment lordosis/kyphosis
• Rapid curve progression (>1 degree per month)
• Functionally disruptive pain
• Focal neurologic findings
• Male sex
• Pes cavus

Common Pitfalls to Avoid

• Assuming no progression due to absence of symptoms - curves can progress silently, particularly in skeletally immature patients 7
• Delaying evaluation when new symptoms develop - new neurological symptoms, rapid progression, or focal findings require urgent evaluation 7
• Excessive radiation exposure - follow recommended monitoring intervals rather than obtaining frequent radiographs 7
• Overlooking neural axis abnormalities - up to 2-4% of adolescent idiopathic scoliosis patients have neural axis abnormalities that should be evaluated before surgery 8, 2

Surgical Approach When Indicated

• Posterior spinal fusion with instrumentation is the standard surgical approach for curves exceeding surgical thresholds 1
• Bone grafting (allograft and/or autograft) is necessary to achieve solid arthrodesis 1, 2
• Segmental pedicle screw constructs or hybrid constructs using pedicle screws, hooks, and wires represent current best practice 3