Determining the optimal mechanical requirements for early intervention devices in the knee
Determining the optimal mechanical requirements for early intervention devices in the knee
Interpositional arthroplasty is a treatment option for isolated medial compartment
osteoarthritis of the knee. No bone resection and no mechanical fixation
are the main advantages of this procedure. However post-operative problems,
such as implant dislocation, swelling and severe knee pain have been generally
observed. Since these problems are related to the motions and loads occurring
at the knee and probably to design factors of the implant, there is a need to
investigate the kinematics and contact mechanics of the knee implanted with an
interpositional spacer and its differences with respect to the normal knee. Although
the knee joint is routinely involved in dynamic activities, to date, no
experimental or numerical studies have investigated the kinematics and contact
mechanics of the normal knee joint during dynamic loading conditions, most of
the experimental and finite element studies are static or quasi-static in nature.
Hence the purpose of this study was to investigate: 1) the behaviour of the
normal knee joint under dynamic loading conditions, 2) the performance of a
knee implanted with an interpositional spacer and 3) the effect of several implant
design parameters on the behaviour of the implanted knee. The kinematics and
contact pressures of the normal knee joint during the activities of walking, stair
ascent and squatting were obtained using dynamic finite element analysis. Higher
contact pressures were predicted when applying more demanding loads, during
the simulation of the squatting and stair ascent activities. Similar ranges of motion
were predicted for the three activities simulated, despite the difference in the
magnitude of the loads applied, due to the restraining function of the ligaments
and the geometry of the surfaces into contact. In the second study, the kinematics
and contact pressures of a knee implanted with a polyurethane interpositional
spacer were obtained and compared to the normal knee. In general, for the three
activities simulated, the implanted knee was able to follow the kinematics of the
normal knee, however higher contact pressures were predicted in the medial side
of the tibial and femoral articular cartilages, which could increase the propensity
for articular cartilage degeneration. In the third study, the influence of implant
material, size, thickness and radii of the bearing surface in anterior/posterior and
medial/lateral directions was assessed. A hard material compared to the menisci,
such as a cobalt-chromium alloy, caused higher contact pressures in both the medial
and lateral side of the knee. Implant size did not affect the kinematics or
contact pressures in the knee, however anterior dislocation of the implant was
observed for a large spacer during the squatting activity. Thickness and radii of
the bearing surface did not show any significant influence on the kinematics or
contact pressures.
Esteban, Sara Checa
6acb8e55-4152-412c-9acf-2f7a26ef693d
July 2007
Esteban, Sara Checa
6acb8e55-4152-412c-9acf-2f7a26ef693d
New, Andrew
d2fbaf80-3abd-4bc5-ae36-9c77dfdde0d6
Taylor, Mark
e368bda3-6ca5-4178-80e9-41a689badeeb
Esteban, Sara Checa
(2007)
Determining the optimal mechanical requirements for early intervention devices in the knee.
University of Southampton, School of Engineering Sciences, Doctoral Thesis, 231pp.
Record type:
Thesis
(Doctoral)
Abstract
Interpositional arthroplasty is a treatment option for isolated medial compartment
osteoarthritis of the knee. No bone resection and no mechanical fixation
are the main advantages of this procedure. However post-operative problems,
such as implant dislocation, swelling and severe knee pain have been generally
observed. Since these problems are related to the motions and loads occurring
at the knee and probably to design factors of the implant, there is a need to
investigate the kinematics and contact mechanics of the knee implanted with an
interpositional spacer and its differences with respect to the normal knee. Although
the knee joint is routinely involved in dynamic activities, to date, no
experimental or numerical studies have investigated the kinematics and contact
mechanics of the normal knee joint during dynamic loading conditions, most of
the experimental and finite element studies are static or quasi-static in nature.
Hence the purpose of this study was to investigate: 1) the behaviour of the
normal knee joint under dynamic loading conditions, 2) the performance of a
knee implanted with an interpositional spacer and 3) the effect of several implant
design parameters on the behaviour of the implanted knee. The kinematics and
contact pressures of the normal knee joint during the activities of walking, stair
ascent and squatting were obtained using dynamic finite element analysis. Higher
contact pressures were predicted when applying more demanding loads, during
the simulation of the squatting and stair ascent activities. Similar ranges of motion
were predicted for the three activities simulated, despite the difference in the
magnitude of the loads applied, due to the restraining function of the ligaments
and the geometry of the surfaces into contact. In the second study, the kinematics
and contact pressures of a knee implanted with a polyurethane interpositional
spacer were obtained and compared to the normal knee. In general, for the three
activities simulated, the implanted knee was able to follow the kinematics of the
normal knee, however higher contact pressures were predicted in the medial side
of the tibial and femoral articular cartilages, which could increase the propensity
for articular cartilage degeneration. In the third study, the influence of implant
material, size, thickness and radii of the bearing surface in anterior/posterior and
medial/lateral directions was assessed. A hard material compared to the menisci,
such as a cobalt-chromium alloy, caused higher contact pressures in both the medial
and lateral side of the knee. Implant size did not affect the kinematics or
contact pressures in the knee, however anterior dislocation of the implant was
observed for a large spacer during the squatting activity. Thickness and radii of
the bearing surface did not show any significant influence on the kinematics or
contact pressures.
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Published date: July 2007
Organisations:
University of Southampton, Engineering Mats & Surface Engineerg Gp
Identifiers
Local EPrints ID: 64811
URI: http://eprints.soton.ac.uk/id/eprint/64811
PURE UUID: 719716b0-8866-47a1-8672-e0be1e4ce499
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Date deposited: 16 Jan 2009
Last modified: 15 Mar 2024 12:02
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Contributors
Author:
Sara Checa Esteban
Thesis advisor:
Andrew New
Thesis advisor:
Mark Taylor
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