ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

MICROMOTION ANALYSIS OF PRESS FIT RADIAL COMPONENT
OF THE TOTAL WRIST ARTHROPLASTY
S. Meireles 1 , L.J. Berglund 2 , A. Completo 3 , J.A. Simões 4 and K.N. An 5
1. ABSTRACT
A persistent problem related to total wrist arthroplasty is loosening of the distal
component of the implant. The initial stability of the implant immediately following
implantation may be a significant factor. Successful stability resulting in minimal
relative motion at the implant-bone interfaces allows osseointegration to occur thereby
providing a strong attachment between prosthesis and bone. The purpose of this study
was to measure stem-bone micromotion in the proximal component of the Re-Motion
prosthesis immediately following implantation in a cadaveric model. Micromotion at
the radial component was measured for three different loading conditions. Acceptable
amounts of micromotion were measured with this implant for the proximal component.
2. INTRODUCTION
There is considerable debate regarding total wrist arthroplasty (TWA) to treat end-stage
wrist arthritis due to a high number of complications 1-4 . Many surgeons still prefer
fusion 5,6 . However, with the advent of new designs of prostheses, complications seem
less frequent and less devastating 7 and attitudes are gradually changing 5 . The Universal
2 (KMI/Integra Life Sciences Corporation, Plainsboro, NJ, USA), Re-Motion (Small
Bone Innovations, Morrisville, PA, USA), Maestro (Biomet Manufacturing
Corporation, ) and Gibbon (Swemac, Linkoping, Sweden) prostheses are the latest
generation of total wrist implants currently available in the United States. All of them,
except the Gibbon, share the concept introduced by Menon for distal component
fixation utilizing a central stem in the capitate and two adjacent screws in the
surroundings carpus.
In total wrist arthroplasty (TWA) design, stablility is a primary consideration. If the
joint is not stable, it cannot provide pain-free function 8 . The primary stability of a
prosthetic device is related to the occurrence of aseptic loosening 9 . Achieving
appropriate primary fixation is particularly important for cementless arthroplasty to
1 Ph.D. student, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de
Santiago, 3810-193 Aveiro, Portugal
2 B.S., Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905,
USA
3 Ph.D., Department of Mechanical Engineering, University of Aveiro, Campus Universitário de
Santiago, 3810-193 Aveiro, Portugal
4 Ph.D., Department of Mechanical Engineering, University of Aveiro, Campus Universitário de
Santiago, 3810-193 Aveiro, Portugal
5 Ph.D., Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905,
USA