title: Stem taper mismatch has a critical effect on ceramic head fracture risk in modular hip arthroplasty.
abstract: BACKGROUND
  Modular total hip prostheses with ceramic heads are well established in orthopedic surgery and widely used. With the variety of different manufacturers and available designs, components are at risk for mismatch. Several case studies show the potentially devastating effects of mismatch.
  
  
  METHODS
  The aim of this study was to investigate the outcome of one arbitrary component mismatch with commercially available components that appear to provide a stable fixation during assembly. A biomechanical in-vitro analysis of fracture strength (n=5) was carried out in accordance with ISO 7206-10. "Type1" Bi-Metric®-stems were mismatched with "V40" Al2O3ceramic heads.
  
  
  RESULTS
  Mean fracture strength was reduced to about 50% of the recommended FDA minimum by the mismatch (Mean 23.68kN, SD 2.35kN). A small contact area between head and stem taper was identified as a potential key parameter.
  
  
  CONCLUSIONS
  Mixing and matching components can put a patient at greater risk for ceramic head fracture and must be avoided.
authors.affiliation: TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: j.guehrs@tuhh.de.
authors.forename: Julian
authors.initials: J
authors.lastname: Gührs
authors.affiliation: TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: mandy.koerner@tuhh.de.
authors.forename: Mandy
authors.initials: M
authors.lastname: Körner
authors.affiliation: TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: maren.bechstedt@tuhh.de.
authors.forename: Maren
authors.initials: M
authors.lastname: Bechstedt
authors.affiliation: TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: annika.krull@tuhh.de.
authors.forename: Annika
authors.initials: A
authors.lastname: Krull
authors.affiliation: TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: morlock@tuhh.de.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Morlock
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002516:Ceramics; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012307:Risk Factors
keywords: Al(2)O(3); Ceramic head fracture; Head-stem mismatch; Head-taper connection; Mix and match; Total hip replacement