Mathematical models of the knee joint are important tools which have both
theoretical and practical applications. They are used by researchers to fully understand
the stabilizing role of the components of the joint, by engineers as an aid for
prosthetic design, by surgeons during the planning of an operation or during the
operation itself, and by orthopedists for diagnosis and rehabilitation purposes.
The principal aims of knee models are to reproduce the restraining function of
each structure of the joint and to replicate the relative motion of the bones which
constitute the joint itself. It is clear that the first point is functional to the second
one. However, the standard procedures for the dynamic modelling of the knee
tend to be more focused on the second aspect: the motion of the joint is correctly
replicated, but the stabilizing role of the articular components is somehow lost.
A first contribution of this dissertation is the definition of a novel approach —
called sequential approach — for the dynamic modelling of the knee. The procedure
makes it possible to develop more and more sophisticated models of the
joint by a succession of steps, starting from a first simple model of its passive motion.
The fundamental characteristic of the proposed procedure is that the results
obtained at each step do not worsen those already obtained at previous steps, thus
preserving the restraining function of the knee structures.
The models which stem from the first two steps of the sequential approach are
then presented. The result of the first step is a model of the passive motion of
the knee, comprehensive of the patello-femoral joint. Kinematical and anatomical
considerations lead to define a one degree of freedom rigid link mechanism, whose
members represent determinate components of the joint. The result of the second
step is a stiffness model of the knee. This model is obtained from the first one, by
following the rules of the proposed procedure. Both models have been identified
from experimental data by means of an optimization procedure. The simulated
motions of the models then have been compared to the experimental ones.
Both models accurately reproduce the motion of the joint under the corresponding
loading conditions. Moreover, the sequential approach makes sure the results
obtained at the first step are not worsened at the second step: the stiffness model
can also reproduce the passive motion of the knee with the same accuracy than the
previous simpler model.
The procedure proved to be successful and thus promising for the definition of
more complex models which could also involve the effect of muscular forces.
| Identifer | oai:union.ndltd.org:unibo.it/oai:amsdottorato.cib.unibo.it:953 |
| Date | 17 April 2008 |
| Creators | Sancisi, Nicola <1979> |
| Contributors | Parenti Castelli, Vincenzo |
| Publisher | Alma Mater Studiorum - Università di Bologna |
| Source Sets | Università di Bologna |
| Language | English |
| Detected Language | English |
| Type | Doctoral Thesis, PeerReviewed |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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