37. A prospective study on modulation of the apical vertebrae by active apex correction technique for early onset scoliosis

Abstract

BACKGROUND CONTEXT

Active apex correction (APC) is posterior tethering technique in adjunct with guided growth for correction of early onset scoliosis. APC involves inserting tethering pedicle screws at convex side of apex proximal (A1) and distal (A3) to most wedged vertebra (A2) allowing modulation of apex according to Hueter-Volkmann law.

PURPOSE

To assess whether APC allows modulation of apical vertebrae of scoliotic curvature.

STUDY DESIGN/SETTING

Prospective study.

PATIENT SAMPLE

Eleven patients with early onset scoliosis treated by APC and evaluated by EOS imaging technique preoperatively and postoperatively to measure concave and convex heights.

OUTCOME MEASURES

Curve characteristics including Cobb angle, apical vertebral translation (AVT), spinal length T1-T12 and T1-L5, convex and concave height of apical vertebrae measurements.

METHODS

Prospective study including 11 patients with early onset scoliosis treated by APC and evaluated by EOS imaging technique preoperatively and postoperatively to measure concave and convex heights. Excluded patients with follow-up < 2years, missing data on apex modulation, and APC was not primary surgical intervention.

RESULTS

Mean age 8.18 ± 2.27 years, 90% congenital scoliosis and mean follow-up post-surgery 2.36 ± 0.51 years. Compared to preoperatively, concave/convex height ratio at the final follow up increased for A1 (from 0.75 to 0.85, P=0.04), A2 (from 0.71 to 0.78, P=0.04), A3 (from 0.78 to 0.82, P=0.16) but decreased for the untethered vertebra (from 1.00 to 0.97, P=0.06). The statistically significant change at A1 and A2 compared to untethered vertebrae indicates persistent growth in both convex and concave sides with a difference in growth rate following APC and thus modulation of the segment of tethered apical vertebrae, and not solely the most wedged vertebra. Compared to preoperatively, there was significant change in Cobb angle, apical vertebral translation, spinal length T1-T12 and T1-L5 at immediate and was maintained at final follow-up.

CONCLUSIONS

APC as a surgical technique for treatment of early onset scoliosis allowing modulation of the most wedged and adjacent vertebrae at the apex of the curvature, while preserving whole spine correction through growth guidance.

FDA Device/Drug Status

This abstract does not discuss or include any applicable devices or drugs.