The University of Southampton
University of Southampton Institutional Repository

Simulation of the passive and active motions of the replaced knee - effect of malalignment and ligament strains

Simulation of the passive and active motions of the replaced knee - effect of malalignment and ligament strains
Simulation of the passive and active motions of the replaced knee - effect of malalignment and ligament strains

A fully mechanical test rig was developed to simulate a series of passive stability tests;  the rig allowed the strains of the primary knee ligaments to be altered as well as coronal plane alignment.  In addition, the rig was used to conduct contact pressure measurements using Tekscan instrumentation.  It was shown that implant design played a significant role in the passive stability of the replaced knee, and that each design was affected differently by altered ligament strains and component alignment.  Assessment of stability in a certain plane was able to highlight specific surgical inaccuracies;  for example, ligament imbalance was best detected by varus-valgus stability testing.

In phase two of the research, computational finite element (FE) models were created for validation against the experimental test results.  Using explicit FE analysis the experimental passive stability testing was simulated.  There was a good agreement between the FE simulations and the experimental results in terms of displacements, rotations and contact pressures.

The final stage of the research focused on simulating normal gait using the FE models.  After recording the kinematics and contact pressures for the idealised knees, gait was assessed with altered ligament strains and component malalignment.  Results from the present study showed that imbalanced ligaments did not significantly affect the gait kinematics or contact pressures;  however the force distribution across the knee was altered.  It has been reported that post-operative malalignment may be due to imbalanced ligament strains;  this correlates with the present research which showed that immediate post-operative malalignment could occur due to an uneven force distribution caused by imbalanced ligaments.  Slight malalignment did not however significantly alter the kinematics during gait, but did affect the contact pressure distribution.

University of Southampton
Curtis, Neil
487d5f0a-ba7f-4b4d-8a7a-358829cdd5f9
Curtis, Neil
487d5f0a-ba7f-4b4d-8a7a-358829cdd5f9

Curtis, Neil (2004) Simulation of the passive and active motions of the replaced knee - effect of malalignment and ligament strains. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

A fully mechanical test rig was developed to simulate a series of passive stability tests;  the rig allowed the strains of the primary knee ligaments to be altered as well as coronal plane alignment.  In addition, the rig was used to conduct contact pressure measurements using Tekscan instrumentation.  It was shown that implant design played a significant role in the passive stability of the replaced knee, and that each design was affected differently by altered ligament strains and component alignment.  Assessment of stability in a certain plane was able to highlight specific surgical inaccuracies;  for example, ligament imbalance was best detected by varus-valgus stability testing.

In phase two of the research, computational finite element (FE) models were created for validation against the experimental test results.  Using explicit FE analysis the experimental passive stability testing was simulated.  There was a good agreement between the FE simulations and the experimental results in terms of displacements, rotations and contact pressures.

The final stage of the research focused on simulating normal gait using the FE models.  After recording the kinematics and contact pressures for the idealised knees, gait was assessed with altered ligament strains and component malalignment.  Results from the present study showed that imbalanced ligaments did not significantly affect the gait kinematics or contact pressures;  however the force distribution across the knee was altered.  It has been reported that post-operative malalignment may be due to imbalanced ligament strains;  this correlates with the present research which showed that immediate post-operative malalignment could occur due to an uneven force distribution caused by imbalanced ligaments.  Slight malalignment did not however significantly alter the kinematics during gait, but did affect the contact pressure distribution.

Text
981876.pdf - Version of Record
Available under License University of Southampton Thesis Licence.
Download (44MB)

More information

Published date: 2004

Identifiers

Local EPrints ID: 465643
URI: http://eprints.soton.ac.uk/id/eprint/465643
PURE UUID: bcbdb066-5154-4159-b6ed-7bae60f544fb

Catalogue record

Date deposited: 05 Jul 2022 02:16
Last modified: 05 Jul 2022 06:03

Export record

Contributors

Author: Neil Curtis

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×