title: Strategy for salvage pedicle screw placement: A technical note.
abstract: BACKGROUND
  Salvage surgery for failed lumbar spine fusion with a loosened pedicle screw is challenging. In general, the strategy includes replacement with larger and longer pedicle screws, augmentation with polymethylmethacrylate cement or hydroxyapatite granules, and extension of fused segments. The purpose of this study is to introduce a new technique for pedicle screw replacement after failed lumbar spine fusion.
  
  
  METHODS
  Five salvage operations were performed using a different trajectory (DT) pedicle screw replacement technique based on 3-dimensional radiological information. Position of the alternative pedicle screws was planned carefully on the computer screen of a computed tomography-based navigation system before the operation. To obtain sufficient initial stability, 1 of 2 techniques was chosen, depending on the patient. One technique created a completely new route, which did not interfere with the existing screw hole, and the other involved penetration of the existing screw hole.
  
  
  RESULTS
  DT pedicle screws were replaced successfully according to the preoperative plan. In all patients, bony union were achieved at the final follow-up period without any instrument failure. Extension of the fused segments could be avoided by using the DT pedicle screw replacement technique combined with transforaminal lumbar interbody fusion.
  
  
  CONCLUSIONS
  The DT pedicle screw replacement technique is a treatment option for salvage lumbar spine surgery.
  
  
  CONCLUSIONS
  The current technique is a treatment option for salvage operations that can both avoid extension of a fused segment and achieve successful bony union.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Fujibayashi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Takemoto
authors.affiliation: Department of Orthopaedic Surgery, Osaka Medical College, Osaka, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Neo
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Matsuda
keywords: Pedicle screw; Salvage surgery; Spinal fixation