Redefining Success and Characterizing Midterm Growth Modulation: Analysis of Radiographic Outcomes in 2 Years...

Area of Science:

• Spine surgery
• Orthopedic surgery
• Pediatric orthopedics

Background:

• Vertebral body tethering (VBT) is a fusionless treatment for idiopathic scoliosis.
• Midterm growth modulation and success predictors after VBT require further characterization.

Purpose of the Study:

• Establish a clinically relevant success criterion for VBT.
• Characterize growth modulation kinetics and identify associated predictors.

Main Methods:

• Multicenter prospective study with ≥2-year follow-up after VBT.
• Defined success as Cobb angle <35° and/or correction rate (CR) ≥50% without overcorrection.
• Analyzed coronal CR, spinal alignment, vertebral rotation, and pelvic obliquity.

Main Results:

• Coronal CR reached 63.2% at 24 months; spinal alignment and pelvic obliquity showed minimal changes.
• Significant improvements in apical and upper end vertebral rotation were observed.
• A higher revision rate occurred in cases meeting the <35° criterion but not the ≥50% CR criterion (28.6% vs. 4.0%).
• Overcorrection risk factors included greater flexibility, younger Risser sign, lower BMI, and higher immediate CR.

Conclusions:

• VBT effectively corrects coronal and axial deformities.
• A success criterion of ≥50% CR without overcorrection is a better indicator of favorable outcomes than a <35° Cobb angle at 2 years.
• Skeletally immature, lean patients with high flexibility require careful monitoring for overcorrection risk.