1. Fredrick G. Reighard, MPH
Anterior Spinal Growth Tethering Leads to Asymmetric Growth of the Apical Vertebra
Peter O. Newton, MD
Yi Yang, FRACS
Megan Jeffords, MS
Tracey P. Bastrom, MA
Carrie E. Bartley, MA
Fredrick G. Reighard, MPH
Burt Yaszay, MD
San Diego – Orthopedics

2. Introduction
Anterior spinal growth tethering (ASGT) is a relatively new non-fusion method of spinal growth modulation that aims to create asymmetric growth of vertebrae resulting in progressive scoliosis correction during the adolescent growth spurt.
The purpose of this study was to evaluate if ASGT results in asymmetrical apical vertebral body growth and scoliosis correction.

3. Methods
A retrospective review of patients treated with ASGT between 2011 and 2014 was conducted.
Patients with >17 months of follow-up and simultaneous biplanar x-rays were required for inclusion.
Patients were excluded if there was evidence of tether breakage prior to 18 months of follow-up.

4. Methods 3D reconstructions made using sterEOS software
Shapes of each apical vertebra and disc were serially evaluated and quantified via Matlab code.

5. Methods
The rate of change over time in each variable of interest was calculated for the individual patients and compared between two groups
patients with correction/improved Cobb angle
those with no correction/continued progression.

6. Results 13 subjects included
9 had progressive improvement in their scoliosis
4 did not further improve or worsened.
Pre-op
Avg age: 11.8±1.8 years
Pre-op Cobb magnitude: 51±11° (35°-69°).
All patients were Risser 0
Post-op
Follow-up ranged from mo with a range of 4 to 7 post-operative visits.
Initial post-op Cobb magnitude was reduced to 34± 8°.
>25 degree group and <15 degree group

7. Results
The correction group showed increased vertebral height over time on the concave side of the curve (0.11mm/mo), as compared to the no correction group (0.01mm/mo, p=0.005).

8. Results
Over time, the correction group demonstrated significantly less apical vertebral wedging in the coronal plane, (ave rate of change -0.11°/mo) compared to the no correction group (0.04°/mo, p=0.02).
No other significant differences were observed between groups.

9. Conclusions
ASGT in immature patients with thoracic scoliosis has the potential to asymmetrically modulate the growth of the apical vertebra.
Greater concave sided growth was associated with greater degrees of overall Cobb angle correction.