title: Concept of patient-specific shape memory implants for the treatment of orbital floor fractures.
abstract: OBJECTIVE
  We will aim to develop implants made of a Ni-Ti shape memory alloy which can be applied for the treatment of midface fractures, such as isolated orbital floor fractures. These can then be implanted in a compressed form and unfold automatically in the body. With the help of newly developed application instruments, the implants can be applied along transnasal and transantral approaches into the maxillary sinus. Our objective is to evaluate the operation process and the functionality of these implants, already in a pre-investigation by an experienced surgeon on a phantom.
  
  
  METHODS
  The functionality of the surgical procedure and an implant prototype were both evaluated with the help of a realistic phantom. The minimally invasive application was carried out using the transnasal and transantral approach. Instruments and implant were rated individually on a scale, from -2 (not at all) to +2 (very good) for vaious criteria, such as the implants functionality or the ergonomics of the entire procedure. For a geometric comparison between the manufactured implant and the planned target geometry, the implants were scanned by micro-computed tomography. CAD models were derived from the scans by using reverse engineering.
  
  
  RESULTS
  Both the implants and the application procedure were assessed as good; thus, the implant concept is suitable for further development.
  
  
  CONCLUSIONS
  Implants made of shape memory alloys could allow in the future and allow less invasive access to treat orbital floor fractures. The implant design has to be modified that the implant can be stabilized and fixed with screws or a suture to avoid dislocation or implant loosening. The complication rates and risks of conventional orbital reconstructions should be lowered by this new method.
authors.affiliation: Fraunhofer Institute for Machine Tools and Forming Technology IWU, Noethnitzer Straße 44, 01187, Dresden, Germany. ronny.grunert@iwu.fraunhofer.de.|Department of Orthopaedics, Traumatology and Plastic Surgery, University Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany. ronny.grunert@iwu.fraunhofer.de.
authors.forename: Ronny
authors.initials: R
authors.lastname: Grunert
authors.affiliation: Hannover Medical School, Clinic for Cranio-Maxillo-Facial Surgery, Carl-Neubergstrasse 1, 30625, Hannover, Germany.|Clinic for Cranio-Maxillo-Facial Surgery, University Hospital Zuerich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Wagner
authors.affiliation: Fraunhofer Institute for Machine Tools and Forming Technology IWU, Noethnitzer Straße 44, 01187, Dresden, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Rotsch
authors.affiliation: Clinic for Cranio-Maxillo-Facial Surgery, University Hospital Zuerich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: Harald
authors.initials: H
authors.lastname: Essig
authors.affiliation: Department of Otorhinolaryngology/Plastic Surgery, Hospital Dresden Friedrichstadt, Friedrichstrasse 41, 01067, Dresden, Germany.
authors.forename: Susanna
authors.initials: S
authors.lastname: Posern
authors.affiliation: Department of Otorhinolaryngology/Plastic Surgery, Hospital Dresden Friedrichstadt, Friedrichstrasse 41, 01067, Dresden, Germany.
authors.forename: Friedemann
authors.initials: F
authors.lastname: Pabst
authors.affiliation: Fraunhofer Institute for Machine Tools and Forming Technology IWU, Noethnitzer Straße 44, 01187, Dresden, Germany.
authors.forename: Welf-Guntram
authors.initials: WG
authors.lastname: Drossel
authors.affiliation: Hannover Medical School, Clinic for Cranio-Maxillo-Facial Surgery, Carl-Neubergstrasse 1, 30625, Hannover, Germany.|Department for Oral & Maxillofacial Surgery, University of Kiel, Arnold-Heller-Strasse 3, 24105, Kiel, Germany.
authors.forename: Juergen
authors.initials: J
authors.lastname: Lichtenstein
mesh_terms: D003722:Dental Alloys; D006801:Humans; D019060:Minimally Invasive Surgical Procedures; D009532:Nickel; D009917:Orbital Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D019736:Prostheses and Implants; D011474:Prosthesis Design; D014025:Titanium; D014057:Tomography, X-Ray Computed
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Implants; NiTi; Orbital floor fractures; Orbital reconstruction; Shape memory alloys