Clinical Orthopaedics and Related Research®

, Volume 471, Issue 2, pp 519–526

What Factors Affect Posterior Dislocation Distance in THA?

  • Jim Nevelos
  • Aaron Johnson
  • Christopher Heffernan
  • James Macintyre
  • David C. Markel
  • Michael A. Mont
Symposium: Papers Presented at the Annual Meetings of The Hip Society

DOI: 10.1007/s11999-012-2559-1

Cite this article as:
Nevelos, J., Johnson, A., Heffernan, C. et al. Clin Orthop Relat Res (2013) 471: 519. doi:10.1007/s11999-012-2559-1

Abstract

Background

Dislocation remains common after total hip arthroplasty. Efforts have been made to identify and minimize risk factors. One such factor, jump distance, or the distance the femoral head must travel before dislocating, has been poorly characterized with respect to three-dimensional kinematics.

Questions/purposes

We therefore determined: (1) the three-dimensional stability of four different component designs; (2) whether the degree of abduction and anteversion affects the stability; (3) whether pelvic inclination angles affected stability; and (4) which combination of these three factors had the greatest stability.

Methods

We created a positionable three-dimensional model of a THA. Acetabular components were modeled in various abduction and anteversion angles and in two different pelvic inclinations which simulate standing and chair-rising activities.

Results

The posterior horizontal dislocation distance increased as inclination angle and femoral head size increased. The 48-mm resurfacing typically had lower jump distances and was at risk of posterior edge loading at 30° inclination. The highest jump distance for all positions and activities occurred with the dual-mobility bearing.

Conclusion

These findings suggest that monoblock cups require extremely accurate positioning for low dislocation risk and that pelvic orientation may increase dislocation risks.

Clinical Relevance

As a result of the dual-mobility designs having the greatest resistance to dislocation, these cups may be appropriate for patients who are at risk for dislocation in difficult primary situations and in revision hip arthroplasty procedures in which proper component orientation may be less likely to be achieved.

Copyright information

© The Association of Bone and Joint Surgeons® 2012

Authors and Affiliations

  • Jim Nevelos
    • 1
  • Aaron Johnson
    • 3
  • Christopher Heffernan
    • 1
  • James Macintyre
    • 1
  • David C. Markel
    • 2
  • Michael A. Mont
    • 3
  1. 1.Stryker OrthopaedicsMahwahUSA
  2. 2.Providence Hospital, DMC-Providence Residency ProgramSouthfieldUSA
  3. 3.Center for Joint Preservation and Reconstruction, Rubin Institute for Advanced OrthopedicsSinai Hospital of BaltimoreBaltimoreUSA