Continued vertebral body growth in patients with juvenile idiopathic scoliosis following vertebral body stapling.

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To quantitatively measure the rate of growth of vertebral bodies in juvenile idiopathic scoliosis (JIS) treated with vertebral body stapling (VBS). VBS has been suggested to be a safe and effective method for modulating the growth of the young scoliotic spine, but few long-term studies have examined its efficacy.

METHODS

Seven patients with JIS 11 years of age or younger underwent VBS with a minimum 6-year follow-up. Vertebral body height on the unstapled and stapled aspects of the curve was measured from initial and final postoperative radiographs and converted into rate of growth per year. Known staple dimensions were used to standardize the measurements between radiographs. Interstaple distance was measured to demonstrate continued growth of the spine. Adjacent vertebral bodies without instrumentation served as an internal control of growth. Each vertebral body (n = 35) was analyzed as an individual experimental unit.

RESULTS

The average rate of growth was 0.86 mm/year (standard deviation [SD] 0.44, 95% confidence interval [CI] 0.71-1.0) per vertebral body on the stapled side and 0.83 mm/year (SD 0.46, 95% CI 0.67-0.98) per vertebral body on the unstapled side of the vertebral body. The adjacent vertebral body segments grew at a rate of 0.91 mm/year (SD 0.42, 95% CI 0.66-1.15) on the stapled side and 0.99 mm/year (SD 0.66, 95% CI 0.61-1.37) on the unstapled side, p < 0.01. The distance between staples increased significantly from 3.0 mm (SD 2.0, 95% CI 2.3-3.6) to 8.4 mm (SD 2.4, 95% CI 7.7-9.3).

CONCLUSIONS

Vertebral body growth in the presence of VBS occurred at a similar rate on the stapled and unstapled sides of the curve. The high standard deviation of instrumented segment growth further supports the conclusion that VBS is not a reliable method of growth modulation in the young scoliotic spine.

LEVEL OF EVIDENCE

IV.