What are the evaluation and management options for thoracic scoliosis?

Evaluation and Management of Thoracic Scoliosis

Initial Evaluation

Begin with standing posteroanterior (PA) and lateral radiographs of the complete spine to measure the Cobb angle, assess curve severity, classify the deformity, and evaluate skeletal maturity using the Risser index. 1

Key Clinical Assessment Points

• Measure the Cobb angle on PA radiographs to quantify curve magnitude—this is the primary determinant of management strategy 1, 2
• Assess skeletal maturity using the Risser index (iliac apophysis ossification) to predict progression risk 1
• Evaluate for neurologic deficits including focal weakness, abnormal reflexes, sensory changes, or pes cavus 3
• Screen for atypical features such as left thoracic curves, short segment curves, rapid progression, or pain—these warrant MRI evaluation 2, 4

When to Obtain MRI

MRI of the complete spine without contrast is mandatory before any surgical intervention and should be obtained in specific high-risk scenarios. 1, 2

MRI is indicated when:

• Any congenital scoliosis (21-43% have intraspinal anomalies including tethered cord, syringohydromyelia, or diastematomyelia) 4
• Left thoracic curve pattern 2, 4
• Short segment curves 2, 4
• Rapid curve progression 2
• Pain or neurologic symptoms 2, 3
• Early onset scoliosis (age 0-9 years) 4

Critical pitfall: A normal neurologic examination does not rule out intraspinal abnormalities—physical exam accuracy is only 62% for detecting these lesions. 4

Management Algorithm Based on Curve Severity

Curves <20° in Skeletally Immature Patients

• Observation with serial radiographs every 12 months for Risser 0-3, or every 18 months for Risser 4-5 2, 4
• Progression risk is <30% 4
• No active treatment required 4

Curves 20-50° in Skeletally Immature Patients

• High progression risk (>70%) if Cobb angle >20° in skeletally immature individuals 1, 2
• Consider bracing for curves 20-40° with remaining growth potential 4
• Serial monitoring every 6 months maximum 1, 4
• Surgical intervention typically indicated when curves reach 40-50° with remaining growth potential to prevent further progression 4

Curves >50° in Skeletally Mature Patients

Surgical intervention is recommended for curves exceeding 50° in skeletally mature patients because these curves continue to progress at approximately 1° per year even after skeletal maturity. 2, 4

Additional surgical indications include:

• Documented progression despite skeletal maturity 2, 4
• Intractable pain not responding to conservative measures 2
• Significant cosmetic concerns affecting quality of life 2

Surgical Planning and Preoperative Evaluation

Imaging Requirements

• MRI of entire spine is mandatory before surgery to rule out neural axis abnormalities (present in >20% of severe curves) 2
• CT with multiplanar reconstruction for presurgical planning reduces screw misplacement from 15.3% to 6.5% 1, 4
• Assess curve flexibility using side bending, push prone, fulcrum bending, or traction radiographs to guide surgical approach 2

Medical Optimization (Especially for Severe Curves)

Preoperative evaluation by pulmonology and cardiology at least 2 months before surgery is essential to allow time for intervention. 1, 2

Required preoperative assessments:

• Pulmonary function testing to assess baseline lung function 1, 2
• Sleep study or nocturnal oximetry to screen for hypoventilation—if abnormal, initiate noninvasive ventilation before surgery 1, 2
• Cardiology evaluation to assess for cardiomyopathy or arrhythmia risk, particularly important before cardiac function deteriorates 1, 2
• Nutritional optimization to support healing and minimize complications 2

Optimal surgical timing is while lung function remains satisfactory (typically FVC >40%) and before cardiomyopathy becomes severe enough to risk arrhythmia under anesthesia. 1

Surgical Approach

• Posterior spinal fusion with instrumentation is the standard approach for most thoracic curves exceeding surgical thresholds 4
• Thoracic pedicle screw constructs provide superior coronal correction (47.5° correction) compared to hook-only constructs (37.7° correction) for large curves 70-100° 5
• Anterior release may not be necessary for curves 70-100° when using modern pedicle screw constructs, as they achieve similar correction to combined anterior-posterior approaches 5
• Bone grafting (allograft and/or autograft) is necessary to achieve solid arthrodesis 2, 4

Postoperative Management

Aggressive airway clearance and respiratory support are critical postoperatively, with follow-up by a pulmonologist specializing in respiratory care. 1, 2

Key postoperative considerations:

• If preoperative sleep studies showed hypoventilation, extubate to noninvasive ventilation postoperatively 1, 2
• Titrate pain management to promote airway clearance while minimizing respiratory suppression 1, 2
• Monitor for mucus plugs if tracheostomy is present 1

Special Considerations for Congenital Scoliosis

MRI of the complete spine is mandatory before any treatment decision in congenital scoliosis due to the 21-43% prevalence of intraspinal anomalies. 4

• Unilateral bar with contralateral hemivertebra has extremely high progression risk (>10° per year) 1, 4
• Isolated hemivertebra has 28% intraspinal anomaly rate 4
• Never assume normal neurologic exam rules out intraspinal pathology—exam accuracy is only 62% 4

Common Pitfalls to Avoid

• Do not assume pain is solely from scoliosis—thoracic disc herniations can present with burning pain and require different management 3
• Do not skip MRI in congenital scoliosis or atypical presentations—up to 43% have intraspinal anomalies that alter surgical planning 4
• Do not delay evaluation of new neurologic symptoms—development of myelopathic signs requires urgent imaging and potential surgical evaluation 3
• Do not order routine MRI without red flags or neurologic deficits in typical adolescent idiopathic scoliosis—it is not supported and unlikely to change management 3
• Do not assume curves will not progress after skeletal maturity—thoracic curves >50° progress at 1° per year even in adults 2, 4