Curve Modulation and Apex Migration Using Shilla Growth Guidance Rods for Early-onset Scoliosis at 5-Year Follow-up

Area of Science:

• Spinal surgery
• Pediatric orthopedics
• Skeletal deformity correction

Background:

• The Shilla procedure aims to correct early-onset spinal deformities while preserving spinal growth.
• It enables controlled axial skeletal growth, potentially reducing the need for frequent implant lengthening surgeries.

Purpose of the Study:

• To investigate trends in spinal curve evolution following Shilla implantation.
• To understand how these changes influence long-term outcomes in pediatric patients.

Main Methods:

• Retrospective review of 21 patients with Shilla implants for at least 5 years.
• Analysis of coronal curve characteristics (preoperative, postoperative, last follow-up).
• Assessment of apex migration, compensatory curve development, spinal growth, and need for definitive fusion.

Main Results:

• The curve apex migrated caudally in 57% of patients (mean 2.7 vertebral levels).
• Two patients developed new compensatory curves; all patients showed spinal growth (mean 45 mm).
• At skeletal maturity, 10 patients had definitive spinal fusion, and 3 had implant removal.

Conclusions:

• The fused primary curve apex shifts in 62% of patients, predominantly distally.
• Findings suggest distal adding-on rather than a crankshaft phenomenon around the apex.
• Improved understanding of Shilla mechanics may refine patient and instrumentation level selection.