Biomedical Engineering Reference
In-Depth Information
palpated ALs. Without careful palpation during data collection, simulation results
may lead to poor visualization.
9.2.2 Joint Kinematics Data for Shoulder Rhythm Determination
This section describes the experimental protocol used to collect joint kinematics
related to the shoulder complex in order to perform ShRm estimation through a
newly-developed approximation method. The aim of the method is to allow the
following pipeline:
•
Numerical data on the orientation and position of the humerus related to the thorax
is first collected.
•
Then, the collected data are processed by the newmethod to estimate the orientation
and position of the scapula and clavicle.
ShRm and Shoulder Motion Datasets
Datamust be collected in order to determine the relationships between on the one hand
the humerus behavior and, on the other hand the related displacements of the clavicle
and scapula. These relationships will be used for defining the “shoulder rhythm
mechanism”. It has been already stressed that it is recognized that muscle tension
play an important role to explain the scapula displacements along the thorax [
75
,
76
],
evenmore than for any other joints inwhich joint stability is less dependent onmuscle
control. This explains why differences are observed between ex-vivo measurements
performed on cadaveric specimens and during active in-vivo shoulder data. It is
therefore of importance that modeling activities concentrate on both kind of data.
For this reason, data collection related to the work presented in this chapter first
concentrates on ex-vivo measurements because it allows, thanks to the nature of the
experiment, accurate kinematic data collection through the use of pins, including
reflective markers, drilled directly into the specimen skeleton. These first datasets
allowed performing a first ShRm estimation. However, the analyzed ex-vivo joint
movements were passive. Supplementary datawere required to assess the precision of
the determined shoulder rhythmduring in-vivo activities (similar to the displacements
visible at Fig.
9.3
). These supplementary data were used in order to improve the
initial model prototype towards a final model usable for both in-vivo and ex-vivo
applications.
In summary, several datasets obtained from various specimens and subjects were
collected. Shoulder kinematic data were acquired from various specimens and vol-
unteering subjects (Table
9.2
). Thirty different datasets were collected from 2 fresh-
frozen specimens: these datasets included passive shoulder displacements in all
conventional anatomical planes (i.e., sagittal, frontal and horizontal planes) and
along intermediary planes. Three volunteers were asked to perform actively sim-
