title: Lumbar transpedicular implant failure: a clinical and surgical challenge and its radiological assessment.
abstract: METHODS
  It is a multicenter, controlled case study review of a big scale of pedicle-screw procedures from January 2000 to June 2010. The outcomes were compared to those with no implant failure.
  
  
  OBJECTIVE
  The purpose of this study was to review retrospectively the outcome of 100 patients with implant failure in comparison to 100 control-patients, and to study the causes of failure and its prevention.
  
  
  BACKGROUND
  Transpedicular fixation is associated with risks of hardware failure, such as screw/rod breakage and/or loosening at the screw-rod interface and difficulties in the system assembly, which remain a significant clinical problem. Removal or revision of the spinal hardware is often required.
  
  
  METHODS
  Two hundred patients (88 women, 112 men) were divided into 2 major groups, with 100 patients in group I (implant failure group G1) and 100 patients in group II (successful fusion, control group G2). We subdivided the study groups into two subgroups: subgroup a (single-level instrumented group) and subgroup b (multilevel instrumented group). The implant status was assessed based on intraoperative and follow-up radiographs.
  
  
  RESULTS
  Implant failure in general was present in 36% in G1a, and in 64% in G1b, and types of implant failure included screw fracture (34%), rod fracture (24%), rod loosening (22%), screw loosening (16%), and failure of both rod and screw (4%). Most of the failures (90%) occurred within 6 months after surgery, with no reported cases 1 year postoperatively.
  
  
  CONCLUSIONS
  We tried to address the problem and study the causes of failure, and proposed solutions for its prevention.
authors: Department of Neurosurgery, Faculty of Medicine, Cairo University, Cairo, Egypt.
authors: Mohamed M
authors: MM
authors: Mohi Eldin
authors: Department of Orthopedic Surgery, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
authors: Abdel Mohsen Arafa
authors: AM
authors: Ali
keywords: Fracture fixations, prosthesis; Fusion; Loosening; Lumbar, fixation; Screw, failure