Julian Gührs1, Mandy Körner2, Maren Bechstedt3, Annika Krull4, Michael M Morlock5. 1. TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: j.guehrs@tuhh.de. 2. TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: mandy.koerner@tuhh.de. 3. TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: maren.bechstedt@tuhh.de. 4. TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: annika.krull@tuhh.de. 5. TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany. Electronic address: morlock@tuhh.de.
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" Al2O3 ceramic heads. FINDINGS: 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. INTERPRETATION: Mixing and matching components can put a patient at greater risk for ceramic head fracture and must be avoided.
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" Al2O3 ceramic heads. FINDINGS: 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. INTERPRETATION: Mixing and matching components can put a patient at greater risk for ceramic head fracture and must be avoided.
Authors: Keith Tucker; Klaus-Peter Günther; Per Kjaersgaard-Andersen; Jörg Lützner; Jan Philippe Kretzer; Rob G H H Nelissen; Toni Lange; Luigi Zagra Journal: EFORT Open Rev Date: 2021-11-19