Biomedical Engineering Reference
In-Depth Information
The analogical and empirical approach to prosthesis design relies on practices,
tools, choices, etc. specific to the medical and industrial sectors concerned.
Before a reconstruction of the natural joint can be produced, it first has to be
characterized and then the model is gradually built up. From observing the physical
phenomena involved (geometry and behavior on contact, etc.) perspectives for
experimental analysis can be decided on [
15
,
16
]. This characterization provides
a set of results and input data on which a preliminary model can be based. By
exploiting the possibilities of this model and assessing its robustness it can be further
strengthened and validated.
Simulation can often lead to more creative proposals for solutions, using
new technologies (material, treatments, production, etc.) or innovative functional
diagrams.
1.2
Protocol to Characterize TMJ Biomechanics
First, using a “mechanism theory” approach, the temporomandibular joint is likened
to a mechanical joint between two undeformable solid bodies. The term joint here
refers to the “contact” between the two elements. By its nature (localized, applied
linearly or across a surface) and its geometry (surface area), this contact partially
enables the six possible relative movements to take place and ensures that articular
forces are transmitted.
The relationship between degrees of freedom (mobility) of the natural joint and
forces that can be transmitted was characterized using results from three types of
experimental reading:
Cadaver dissections
1
-
to study functional anatomy and the geometry of the
articular surfaces,
Electromyography
2
and MRI
3
-
to study muscle actions,
-
3-D video analysis to study kinematics and observe articular displacements.
1.2.1
Cadaver Dissection
In the protocol, fresh cadavers were dissected so that the contact zones (nature of
the contact) and the muscle anchor points could be observed. The directions of
the muscle forces were determined experimentally by photographic readings and
calculations.
1
Dissections carried out with JC. Coutant in the Medical-Surgical Anatomy Department, Univer-
sity of Bordeaux.
2
Electromyography readings taken at the University of Perm as part of the International Project on
Scientific Cooperation CNRS-RFBR n
ı
4280.
3
MRI images produced at the University Teaching Hospital, Bordeaux.
