Shilla growing rods in a caprine animal model: a pilot study.

There are few good surgical options that allow for continued spinal growth in patients with early-onset scoliosis. The "Shilla" is a growth guidance system that does not require repeated surgical lengthenings. The Shilla system guides growth at the ends of dual rods with the apex of the curve corrected, fused, and fixed to the rods. The growth occurs through the extraperiosteally implanted pedicle screws that slide along the rods at either end of the construct. We implanted 11 2-month-old immature goats with the dual rod system and euthanized all 11 goats 6 months postoperatively. We evaluated plain radiographs, regular computed tomography, microcomputed tomography, physical and histologic examinations, and a microscopic wear analysis. All of the goat spines grew with the implants in place; growth occurred in both the thoracic and lumbar ends of the rods for a total average of 48 mm. None of the implants failed, although we observed minor wear at the rod/screw interface. Growth guidance with the Shilla rod system allowed for continued growth in this goat model.