title: Influence of cerclages on primary stability of tumor megaprostheses subjected to distal femur defects.
abstract: BACKGROUND
  Purpose of this experimental study was to investigate the influence of cerclages on the primary stability of the MUTARS system using distally fractured synthetic femora.
  
  
  METHODS
  4 MUTARS prostheses were implanted in synthetic femora respectively. Groups consisted of 4 intact bones, 4 fractured with cerclages and 4 fractured bones without cerclages. Spatial micromovements were measured with a high-precision rotational setup.
  
  
  RESULTS
  The order from the weakest to the strongest torque transmission of the intact bones was rm1-rm4-rm2-rm3 (p=0.011) and of the fractured bones with cerclages rm4-rm1-rm3-rm2 (p=0.013). The MUTARS stems broke out of the fractured femoral shaft by removing cerclages (p<0.001) and by the influence of bone defect A (p<0.001). Overall micromovements of the intact bones were lower than those of the fractured bones without cerclages (p<0.001) and overall micromovements of the fractured bones with cerclages were lower than those of bones without cerclages (p<0.001).
  
  
  CONCLUSIONS
  Due to high press-fit at the proximal and distal isthmus region fissural fractures of the femur may occur. This should always be taken into account. It is advisable to secure them and provide a prophylaxis for these fissural fractures by means of cerclages.
authors.affiliation: Laboratory of Biomechanics, Justus-Liebig-University Giessen, Paul-Meimberg-Strasse 3, Giessen 35392, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Jahnke
authors.affiliation: Laboratory of Biomechanics, Justus-Liebig-University Giessen, Paul-Meimberg-Strasse 3, Giessen 35392, Germany; Laboratory for Biomechanics and Biomaterials (LBB), Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, Hannover 30628, Germany.
authors.forename: Eike
authors.initials: E
authors.lastname: Jakubowitz
authors.affiliation: Laboratory of Biomechanics, Justus-Liebig-University Giessen, Paul-Meimberg-Strasse 3, Giessen 35392, Germany; Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, Giessen 35392, Germany.
authors.forename: Bernd Alexander
authors.initials: BA
authors.lastname: Ishaque
authors.affiliation: Laboratory of Biomechanics, Justus-Liebig-University Giessen, Paul-Meimberg-Strasse 3, Giessen 35392, Germany; Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, Giessen 35392, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Rickert
authors.affiliation: Laboratory of Biomechanics, Justus-Liebig-University Giessen, Paul-Meimberg-Strasse 3, Giessen 35392, Germany; Department of Orthopaedics and Traumatology, BG Trauma Centre Ludwigshafen, Ludwig-Guttmann-Strasse. 13, Ludwigshafen 67071, Germany. Electronic address: oliver.bischel@gmx.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bischel
mesh_terms: D001696:Biomechanical Phenomena; D001859:Bone Neoplasms / Q000601:surgery*; D001860:Bone Plates; D005269:Femur / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008953:Models, Anatomic; D010027:Osteotomy; D057068:Periprosthetic Fractures / Q000601:surgery*; D011474:Prosthesis Design; D013314:Stress, Mechanical
keywords: Cerclage; Distal femur; Femur defects; Megaprostheses; Primary stability; Tumor