Is vertebral body tethering (VBT) from T6-L3 with double row T9-L2 medically necessary for a 14-year-old male with adolescent idiopathic scoliosis?

Medical Necessity Determination for Vertebral Body Tethering

Vertebral body tethering (VBT) from T6-L3 with double row T9-L2 is NOT medically necessary for this 14-year-old male with a 50-degree thoracolumbar curve, as posterior spinal fusion with instrumentation remains the established standard of care with predictable outcomes and established long-term safety, while VBT is considered investigational with higher revision rates and uncertain long-term outcomes. 1

Rationale for Denial

Standard of Care Considerations

• The established surgical approach for curves exceeding 45-50 degrees in skeletally immature patients is posterior spinal fusion with instrumentation, which has predictable outcomes and established long-term safety through decades of evidence 1

• Posterior spinal fusion achieves solid arthrodesis with predictable outcomes, and long-term effectiveness is well-established 1

• This patient's 50-degree thoracolumbar curve exceeds the 45-50 degree threshold where surgical intervention is indicated for skeletally immature patients, with a progression likelihood exceeding 70% 1

Evidence Status of VBT

• VBT remains an investigational procedure with limited long-term outcome data compared to the gold standard posterior spinal fusion 2

• Recent retrospective case series show correction rates up to 70% but demonstrate greater variability in outcomes compared with posterior spinal fusion 2

• The complication profile differs significantly from posterior spinal fusion, with tether breakage and overcorrection as primary concerns 2

• Revision rates are higher for VBT compared to posterior spinal fusion, with studies reporting 12.3% revision rates including overcorrection and need to span additional vertebrae 3

Patient-Specific Concerns

• This patient has a thoracolumbar curve pattern (Lenke type 6), which is not the optimal indication for VBT 3, 4

• The best indication for VBT is a flexible single major thoracic curve with nonstructural compensating lumbar and proximal thoracic curves (Lenke 1A or 1B) 3

• Studies of bilateral VBT for Lenke type 6 curves show concerning rates of tether breakage and loss of correction, with 22 of 25 patients suspected to have at least one segment with tether breakage 4

• The patient is 14 years old, and optimal VBT candidates are before Risser stage 3 and after triradiate cartilage closure; skeletal maturity status is not clearly documented in this case 3

Required Pre-Operative Evaluation (If Any Surgery Proceeds)

• MRI of the complete spine without contrast must be obtained to rule out neural axis abnormalities including Chiari I malformation, cord syrinx, cord tethering, or intrinsic spinal cord tumor before any surgical intervention 1

• The American College of Radiology recommends MRI of the entire spine is mandatory before any surgical intervention, particularly in thoracolumbar curve patterns where neural axis abnormalities occur in 2-4% of adolescent idiopathic scoliosis patients 1

• Confirmation of skeletal immaturity status with current standing radiographs including Risser grade and triradiate cartilage status is essential 1

Alternative Recommendation

Approve posterior spinal fusion with instrumentation contingent on:

• Pre-operative MRI of complete spine without contrast to evaluate for neural axis abnormalities 1

• Confirmation of skeletal immaturity status 1

• Standard pre-operative medical clearance 1

Common Pitfalls to Avoid

• Do not approve VBT based solely on patient/family preference for motion preservation without considering the established superiority and predictability of posterior spinal fusion 1, 2

• Do not proceed with any spinal surgery without pre-operative MRI to rule out neural axis abnormalities, which occur in more than 20% of patients with severe curves 5

• Do not assume VBT is appropriate for all curve patterns; thoracolumbar curves (Lenke type 6) have shown higher tether breakage rates and loss of correction compared to single thoracic curves 4

• Recognize that the patient's two years of bracing compliance demonstrates failure of conservative management, meeting criteria for surgical intervention, but this does not automatically justify an investigational procedure over the standard of care 1