title: Friction in orthopaedic zirconia taper assemblies.
abstract: The torque resistance of zirconia ceramic heads/titanium taper trunnion junctions was tested in accordance with ISO 7206-9:1994(E); using twelve modified heads of 32 mm diameter under representative physiological conditions. Test parameters studied included assembly force, vertical load during test (test load) and head length. Mean torque resistances measured were 8.9 N m for a 1 kN test load and 15 N m at 4 kN test load. Coefficients of friction calculated for the torsional stability ranged from 0.06 to greater than 1.0. Multiple regression analysis confirmed that the failure torques measured were significantly dependent on test load (beta = 0.77; P < 0.001) whereas assembly force and head length played a lesser, insignificant, part in the variation. Data from push-on/pull-off tests were used to calculate coefficients of friction under axial loading, which were significantly correlated with taper angle and material. Torque testing shows greater variability than push-on/pull-off tests for similar combinations, and for zirconia heads on other tapers. The coefficients of friction measured (0.16-0.31) are significantly different from values typically used in stress analyses.
authors.affiliation: Department of Biomaterials/Handicap Research, Institute for Surgical Sciences, University of Gothenburg, Sweden.
authors.forename: W
authors.initials: W
authors.lastname: Macdonald
authors.forename: A
authors.initials: A
authors.lastname: Aspenberg
authors.forename: C M
authors.initials: CM
authors.lastname: Jacobsson
authors.forename: L V
authors.initials: LV
authors.lastname: Carlsson
mesh_terms: D001672:Biocompatible Materials; D002858:Chromium Alloys; D005270:Femur Head; D017276:Friction; D006622:Hip Prosthesis; D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design; D015203:Reproducibility of Results; D013193:Stainless Steel; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium; D015040:Zirconium
chemical_list: D001672:Biocompatible Materials; D002858:Chromium Alloys; D013193:Stainless Steel; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide