title: PEEK versus titanium locking plates for proximal humerus fracture fixation: a comparative biomechanical study in two- and three-part fractures.
abstract: BACKGROUND
  The high rigidity of metal implants may be a cause of failure after fixation of proximal humerus fractures. Carbon fiber-reinforced polyetheretherketone (PEEK) plates with a modulus similar to human cortical bone may help to overcome this problem. The present study assesses the biomechanical behavior of a PEEK plate compared with a titanium locking plate.
  
  
  METHODS
  Unstable two- and three-part fractures were simulated in 12 pairs of cadaveric humeri and were fixed with either a PEEK or a titanium locking plate using a pairwise comparison. With an optical motion capture system, the stiffness, failure load, plate bending, and the relative motion at the bone-implant interface and at the fracture site were evaluated.
  
  
  RESULTS
  The mean load to failure for two- and three-part fracture fixations was, respectively, 191 N (range 102-356 N) and 142 N (range 102-169 N) in the PEEK plate group compared with 286 N (range 191-395 N) and 258 N (range 155-366 N) in the titanium locking plate group. The PEEK plate showed significantly more bending in both the two- and three-part fractures (p < 0.05), an increased relative motion at the bone-implant interface and lower stiffness values (p < 0.05).
  
  
  CONCLUSIONS
  In this biomechanical study on unstable proximal humerus fractures, fixation with a PEEK plate showed lower fixation strength and increased motion at the bone-implant interface compared with a titanium locking plate.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Albert-Schweitzer-Campus 1, building W1, 48149, Münster, Germany. benedikt.schliemann@ukmuenster.de.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Schliemann
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Albert-Schweitzer-Campus 1, building W1, 48149, Münster, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Seifert
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Albert-Schweitzer-Campus 1, building W1, 48149, Münster, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Theisen
authors.affiliation: AO Research Institute Davos, Clavadelerstrasse 8, 7270, Davos, Switzerland.
authors.forename: Dominic
authors.initials: D
authors.lastname: Gehweiler
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Albert-Schweitzer-Campus 1, building W1, 48149, Münster, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Wähnert
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Albert-Schweitzer-Campus 1, building W1, 48149, Münster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schulze
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Albert-Schweitzer-Campus 1, building W1, 48149, Münster, Germany.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Raschke
authors.affiliation: OCP-Münster, Schaumburgstraße 1, 48145, Münster, Germany.
authors.forename: Andre
authors.initials: A
authors.lastname: Weimann
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001577:Benzophenones; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D001860:Bone Plates; D002102:Cadaver; D002244:Carbon; D000077482:Carbon Fiber; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D007659:Ketones; D008297:Male; D011092:Polyethylene Glycols; D011108:Polymers; D012784:Shoulder Fractures / Q000601:surgery*; D013314:Stress, Mechanical; D014025:Titanium
chemical_list: D001577:Benzophenones; D001672:Biocompatible Materials; D000077482:Carbon Fiber; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D002244:Carbon; D014025:Titanium
keywords: Biomechanics; Locking plate fixation; PEEK plate; PHILOS plate; Proximal humerus fracture