O2127: Vertebral Body Tethering in a Pediatric Spine Deformity Practice: About How Many?

Background: Vertebral body tethering (VBT) serves as an attractive treatment methodology for correction of pediatric spinal deformities due to its potential for increased preservation of flexibility of the instrumented spine. In 2025, the ideal candidate for this procedure includes a patient with growth remaining who would require a fusion into the lumbar spine with a flexible deformity. A relative unknown is the new hybrid approach, harnessing the corrective power of a posterior fusion in the thoracic spine while maintaining lumbar flexibility with a thoracolumbar tether. The aim of this study is to ascertain when given a rigorous set of indications for VBT and a hybrid PSF-VBT, what percentage of a tertiary referral center’s patients would qualify for such procedures?

Methods: We conducted a retrospective analysis of a database of patients with idiopathic scoliosis treated operatively with PSF or VBT at a children’s hospital from 1/1/2016 to 6/25/2019. Indications included: diagnosis of idiopathic scoliosis, age 8-16, Sanders ≤5, and Cobb angle between 50º and 60º. Indications for VBT further required selective lumbar instrumentation defined as the upper instrumented vertebrae at T9 or lower, and a curve which bends to ≥50% of the original curve, while indications for hybrid PSF-VBT required a lowest instrumented vertebrae below L1 and a lumbar curve which bends to ≥50% of the original curve. Patients that lacked a Sanders score were included if they had a Risser score of 0 or 1.

Results: 359 patients with idiopathic scoliosis underwent spinal deformity correction with PSF or VBT. 11 patients (3.1%) were identified as candidates for selective lumbar instrumentation, however 0/11 of the patients satisfied all the inclusion criteria. The most common reason for ineligibility was skeletal maturity. 121 patients with complete clinical data (33.7%) met criteria for the hybrid PSF-VBT procedure. Of these 121 patients, 5 (4.1%) satisfied all necessary inclusion criteria. Top three reasons for ineligibility include skeletal maturity (84/121), curve magnitude (46/121), and lack of lumbar flexibility (23/121).

Conclusion: With narrowing indications, vertebral body tethering surgical volume may not reach that of posterior spine fusion. Over a 3.5-year operative volume at a tertiary referral center, no patients with idiopathic scoliosis qualified for selective lumbar VBT while 5 patients (1.4%) met criteria for a hybrid PSF-VBT procedure. Using strict indications, a full-time pediatric spine surgeon performs less than 10 vertebral body tethering procedures annually based on historic data. As hospital systems develop pathways for idiopathic scoliosis, understanding average annual patient volume is critical.