title: Analysis of complications after reconstruction of bone defects involving complete mandibular resection using finite element modelling.
abstract: BACKGROUND
  In a retrospective study, risk factors for complications after the bridging of mandibular defects using reconstruction plates were reviewed. Especially the loosening of the plate-screw-mandible complex should be analyzed with a finite element model in order to reduce plate complications in future.
  
  
  METHODS
  We examined 60 patients who underwent a treatment with reconstruction plates after tumor resection during a period of 10 years. The problem of screw loosening was additionally reviewed by means of a finite element study, and a model for the loosening process was developed.
  
  
  RESULTS
  Our postoperative examination showed that 26 patients suffered from complications that required an early removal of the plate. These complications were oral or extraoral plate exposures, the looseness of screws with or without plate displacement, and plate fractures. Thereby, we noticed that maxillary and mandibular areas of opposing teeth, the size of the mandible defect, and the crossing of the orofacial midline are all risk factors for plate complications. On the basis of the finite element model, a modified arrangement of the screws was derived. Hence, a new type of resection plate was established.
  
  
  CONCLUSIONS
  By repositioning the screw holes along the long axis of the plate, the transition from tensile force to torque force of the screws in the screw-plate-bone complex can be minimized. Thereby, the complication of screw loosening will be considerably reduced.
authors.affiliation: Klinik für Mund-, Kiefer- und Gesichtschirurgie, Technische Universität Dresden, Germany. Jutta.Markwardt@mailbox.tu-dresden.de
authors.forename: Jutta
authors.initials: J
authors.lastname: Markwardt
authors.forename: Günther
authors.initials: G
authors.lastname: Pfeifer
authors.forename: Uwe
authors.initials: U
authors.lastname: Eckelt
authors.forename: Bernd
authors.initials: B
authors.lastname: Reitemeier
mesh_terms: D001860:Bone Plates; D001863:Bone Screws; D016025:Bone Transplantation; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D003198:Computer Simulation; D017076:Computer-Aided Design; D004868:Equipment Failure; D005260:Female; D020342:Finite Element Analysis; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008339:Mandibular Neoplasms / Q000188:drug therapy / Q000532:radiotherapy / Q000601:surgery*; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000188:drug therapy / Q000532:radiotherapy / Q000601:surgery*; D020360:Neoadjuvant Therapy; D011183:Postoperative Complications / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D019919:Prosthesis Implantation; D018714:Radiotherapy, Adjuvant; D012086:Reoperation; D014025:Titanium
chemical_list: D014025:Titanium