Clinical Orthopaedics and Related Research®

, Volume 471, Issue 2, pp 403–409

Acetabular Cup Design Influences Deformational Response in Total Hip Arthroplasty

  • John B. Meding
  • Scott R. Small
  • Mary E. Jones
  • Michael E. Berend
  • Merrill A. Ritter
Symposium: Papers Presented at the Annual Meetings of The Hip Society

DOI: 10.1007/s11999-012-2553-7

Cite this article as:
Meding, J.B., Small, S.R., Jones, M.E. et al. Clin Orthop Relat Res (2013) 471: 403. doi:10.1007/s11999-012-2553-7

Abstract

Background

Press-fit acetabular components are susceptible to deformation in an underreamed socket, with excessive deformation of metal-on-metal (MOM) components potentially leading to increased torsional friction and micromotion. Specifically, however, it remains unclear how cup diameter, design, and time from implantation affect shell deformation.

Questions/purposes

We asked whether (1) changes in component geometry and material altered maximum shell deformation and (2) time-dependent deformational relaxation processes occurred.

Methods

Diametral deformation was quantified after press-fit implantation of metal shells into a previously validated polyurethane model. Experimental groups (n = 6–8) consisted of 48-, 54-, 60-, and 66-mm MOM cups of 6-mm wall thickness, 58-mm cups of 10-mm wall thickness, and CoCrMo and Ti6Al4V 58-mm modular cups.

Results

Greater cup diameter, thinner wall construction, and Ti6Al4V modular designs generated conditions for maximum shell deformation ranging from 0.047 to 0.267 mm. Relaxation (18%–32%) was observed 120 hours postimplantation in thin-walled and modular designs.

Conclusions

Our findings demonstrate a reduction of shell deformation over time and suggest, under physiologic loading, early component deformation varies with design.

Clinical Relevance

Component deformation should be a design consideration regardless of bearing surface. Designs neglecting to adequately address deformational changes in vivo could be susceptible to diminished cup survival, increased wear, and premature revision.

Copyright information

© The Association of Bone and Joint Surgeons® 2012

Authors and Affiliations

  • John B. Meding
    • 1
  • Scott R. Small
    • 1
  • Mary E. Jones
    • 2
  • Michael E. Berend
    • 1
  • Merrill A. Ritter
    • 1
  1. 1.Joint Replacement Surgeons of Indiana Foundation, IncMooresvilleUSA
  2. 2.Department of Applied Biology and Biomedical EngineeringRose-Hulman Institute of TechnologyTerre HauteUSA

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