[Halm-Zielke instrumentation in idiopathic scoliosis. Results in 25 consecutive patients with a minimum follow-up of 2 years]

Halm-Zielke Instrumentation (HZI) was developed to eliminate the disadvantage of VDS-Zielke in terms of lack of primary stability and in order to simplify sagittal plane control. Since 1993 we study within a prospective clinical trial, whether HZI fulfills these demands.HZI is an anterior double-rod system with a two screw per vertebral body fixation. The longitudinal components consist of a threaded VDS-rod and a solid rod, which are attached to a hinge-conducted lid plate. 25 consecutive patients with idiopathic scoliosis and curves ranging from 36 degrees to 92 degrees were treated with HZI. The follow-up period ranges from 2 to 4 years.Correction of the frontal plane within the instrumented levels averaged 71.4% and 70.4% postoperatively and at follow-up, respectively. Derotation averaged 51.7% and mean correction of the tilt of the lowest instrumented vertebra was 69.5% at final follow-up. Thoracolumbar kyphosis was present in 7 patients and always completely corrected. One implant related complication, a screw breakage 12 months postoperatively without adverse effects was noted. There was no case of pseudarthrosis. All patients were mobilized without any additional external immobilization in terms of a brace or cast and were allowed to go swimming for physio-therapeutical purposes immediately after wound healing.This study proves that HZI is a primary stable implant to perform the Ventral Derotation Spondylodesis. The VDS-typical implant related disadvantages are eliminated. With this the period of rehabilitation is shortened by many months due to avoidance of cast and brace treatment.