title: Dual-rod correction and instrumentation of idiopathic scoliosis with the Halm-Zielke instrumentation.
abstract: METHODS
  A prospective clinical and radiographic evaluation of 45 consecutive patients with idiopathic adolescent and adult scoliosis treated with anterior dual-rod Halm-Zielke instrumentation.
  
  
  OBJECTIVE
  Clinical and radiographic evaluation with a minimum follow-up of 2 years.
  
  
  BACKGROUND
  Halm-Zielke instrumentation was developed to eliminate the disadvantages of Zielke instrumentation in terms of lack of primary stability and a kyphogenic effect.
  
  
  METHODS
  All patients underwent an identical anterior surgical technique with the Halm-Zielke instrumentation of the primary curve. The system is composed of a lid-plate, which is fixed to the lateral aspect of the vertebral body with two screws: a sunk screw anteriorly and a ventral derotation spondylodesis (VDS) screw posteriorly. The lid-plate design provides the lowest possible implant profile. The longitudinal components consist of a threaded rod and a solid, fluted rod. Correction is performed with both the threaded and the solid rod. The solid rod allows derotation and correction of the sagittal plane and provides primary stability.
  
  
  RESULTS
  Preoperative curves ranged from 35 degrees to 92 degrees Cobb angle. Final correction of the frontal plane averaged 67% within the instrumented levels and 59% for the total primary curve. The apical vertebral rotation of the primary curve was corrected by 52% on average without loss of correction during follow-up. Thoracolumbar kyphosis was present in 11 patients and corrected in all cases from an average of 20 degrees to 2 degrees after surgery and to 8 degrees at follow-up. We observed two cases of implant failure with one resulting in a pseudarthrosis.
  
  
  CONCLUSIONS
  Halm-Zielke instrumentation proved to be a major improvement of the original VDS-Zielke. It eliminates the kyphogenic effect and provides primary stability.
authors.affiliation: Department of Orthopaedics, University Hospital of Muenster, Germany. bullmanv@uni-muenster.de
authors.forename: Viola
authors.initials: V
authors.lastname: Bullmann
authors.forename: Henry F
authors.initials: HF
authors.lastname: Halm
authors.forename: Thomas
authors.initials: T
authors.lastname: Niemeyer
authors.forename: Lars
authors.initials: L
authors.lastname: Hackenberg
authors.forename: Ulf
authors.initials: U
authors.lastname: Liljenqvist
mesh_terms: D000293:Adolescent; D000328:Adult; D001860:Bone Plates; D001863:Bone Screws; D002648:Child; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009984:Orthopedic Fixation Devices; D011183:Postoperative Complications; D011446:Prospective Studies; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation*; D016896:Treatment Outcome