Journal of Computer Aided Surgery Vol.5 No.4
Abstract: This paper a new handheld laparoscopic forceps manipulator for
laparoscopic surgery using 2 bending mechanisms by multi-slider linkage
mechanisms to achive high mechanical performance and applicability . A
bending mechanism consisted of 3 outer frames, 2 rotating joints and 2
sliding linkages for drive and restraint. The rotation of the joint was
available by pulling / pushing the adjacent element by sliding linkage
in order . We connected 2 bending mechanisms, one was for the horizeontal
plane bending and the other was for the vertical plane bending, enabling
2-DOFs independent motions between - 90 degrees and ＋ 90 degrees. The
2-DOFs bending mechanism and 1-DOF forceps mechanism were driven by 3 brushless
DC-servomotors. We examined the actual angle of 2-DOFs bending mechanism,
obtaining repeatability of ±0.87 degrees in the horizontal plane bending
and ±0.91 degrees in the vertical plane bending . In an animal experiment
this manipulator performed laparoscopic surgical takes under pneumoperitoneum.
In conclusion, we were sure of a usefulness of multi-slider linkage mechanisms
for the new handheld forceps manipulator to cinical application, which
showed high repeatability of less 1.0 mm manipulation and large working
space with sufficient generated power of end -effector.
Keywords: Multi-slider linkage mechanisms, Laparoscopic, Manipulator.
Abstract: We evaluated the mechanical properities of biodegradable microstructures
produced by a three-dimensional microfabrication system that we had developed.
Biodegradable materials are indispensable in developing modern medical
equipment, but the lack of a suitable processing method is hindering the
application of these materials. Our fabrication system has achieved a high
resolution (50 μm) and the high bio-applicability of the fabricated structure
has been verified by cultivating cell lines in a biodegradable vessel fabricated
using our system . However, the mechanical strength of the fabricated
structure had been unknown. To measure the mechanical strength of our structures,
we fabricated test pieces using Poly(D, L-lactide-co-glycolide) , and subjected
them to a tensile test. In order to evaluate the mechanical strength of
the structures , two types of test piece were prepared , one scanned parallel
to the tensile direction, and the other scanned perpendicular to it. The
strength of our fabricated structure was shown to be about 55 percent of
the tensile strength of structures made from the same material but fabricated
using the conventional method. Our fabrication system is expected to find
applications in tissue engineering in the near future.
Keywords: Three-dimentional microfabrication, Poly-lactide, Biodegradable
polymer, Bioerodible, Tensile strength.
Abstract: The purpose of this study is measurement of forces exerted during
the robotic needle insertion into human vertebra and comparison between
robotic and manual needle insertion. Axial forces exerted during robotic
insertion into human vertebrae fixed with water solution of formaldehyde
did not exceed 25 N when the feed rate was no more than 0.5 mm/s. There
was no statistically significant influence of formaldehyde fixation on
axial forces exerted. The forces exerted during robotic insertion ware
as small as less than 50 % of those during manual insertion partly because
of sufficiently wide angle of the needle twisting.
Keywords: Percutaneous vertebroplasty, Needle insertion, Robot, Force.
Abstract: Purpose: The aim of this study was to analyze the mandibular
movement of a patient with square mandible using the 4-dimensional (4D)
analyzing system , and to suppose the cause of square mandible from characteristics
of the movements.
Methods:Subjects were a healthy volunteer and a patient with square mandible.
A volunteer was a 26-year old fdmale who had no missing teeth and no morbid
findings in clinical examination. A patient was a 37-years old female.
Diagnostic imaging scarcely depicted any disc derangement, but a severely
limited jaw opening was noted . As well , her facial appearance showed
a characteristic ssquare mandible facial configuration .
The skull and mandible were reconstructed into a 3-dimensional (3D) bone
model from the CT data and mandibular movements were recorded by a measurement
device of MM-JI-E(Shofu Inc.). The bone model and mandibular movements
were combined using the 4D analyzing system.
The origin and halt of each masticatory muscle were positioned on the surface
of the 3D bone model, and connected together with a string respectively
. In this system, the color of the string was designed to be passively
changed in accordance with mandibular movements.
Results and Discussion: In this case, the cause of opening limitation was
not the opening muscle itself but contraction of the temporal muscle .
Therefore, it was supposed that the load extended to the masseter muscle
from the temporal muscle depended on the masseter muscle, and resulted
in muscle hypertrophy or angle hyperplasia.
Keywords: Four- dimensional analysis, Mandibular movement, Masticatory
muscle model , Square Mandible.