Growth-guided instrumentation: Shilla procedure

The Shilla growth guidance technique was developed to allow growth of the child’s spine without requiring scheduled returns to the operating room for lengthenings. The center of the deformity (apex) is corrected to a straight alignment in all planes (coronal, sagittal, and axial) with osteotomies, bilateral screw fixation, and corrective maneuvers. Dual stainless steel rods are fixed to the corrected apex with fusion of the apical segments. Extraperiosteally placed sliding pedicle screws with the Shilla cap (which tightens to the screw and not to the rod) above and below the apex allow vertebral growth in a cephalad and caudad direction. Studies of the Shilla system implanted in goats showed that the implants could be safely inserted into small pedicles, no spinal stenosis was produced and the implants slide along the rods as expected. Careful preoperative planning must be carried out including flexibility films. In very stiff curves, anterior release or corrective posterior osteotomies may be necessary. The use of Ponte osteotomies will allow for increased correction. The largest diameter rod permissible should be used to minimize rod fractures. A bivalved form fitting turtle shell orthosis is used for 3 months until the apical fusion has set up. Shilla has been used in many different diagnoses in both single and double curves. Average age at surgery has been 6–8 years. Curves showed 70 % improvement at 5-year follow-up. Shilla has been favorably compared to dual growing rods. The Shilla growth guidance technique offers a method of treatment of EOS allowing spinal growth while controlling the deformity without scheduled repeated returns to the OR. The complication rate is acceptable and multiple diagnoses can safely be treated with the Shilla technique. Patients are allowed to participate in most normal childhood activities.