MIDDLE EAST TECHNICAL UNIVERSITY

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MIDDLE EAST TECHNICAL UNIVERSITY MECHANICAL
ENGINEERING DEPARTMENT ME 590 SEMINAR
Thesis Subject BIOMECHANICAL MODELLING OF HUMAN
HAND
Prepared by Osman KILIÇ Supervisors
Prof. Dr. Turgut TÜMER
Asst. Prof. Ergin
TÖNÜK
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ANATOMY OF THE WRIST
JOINTS
BONES
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VOLAR (PALMAR) LIGAMENTS
DORSAL LIGAMENTS
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FUNCTIONS OF THE WRIST
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SURGICAL PATHOLOGICAL ASPECTS OF THE WRIST
MODEL
Changes in load distribution between carpal bones
is very important for implant applications,
surgical operations and ligament tears.
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Pathological Example
Capitate
Capitate
Scaphoid
Scaphoid
Lunate
Lunate
Extra loading on Lunatum bone due to abnormal
contact structure between Capitate and Lunate.
Cup shaped part of the Capitate is shaved to
remove extra load on Lunate.
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IN LITERATURE
Kinematics of wrist bones are not studied as a
whole structure. Instead, there are studies
containing a few bones which generally focus on
contact forces and relative motion observations.
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Recent studies are about finite element modelling
of wrist bones.
Radius
In all these models, most of the bones, ligaments
and joints are missing.
In order to have high a fidelity model of the
wrist bones, ligaments and joints should be
studied as a whole.
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THESIS STUDIES
The wrist is modeled by using Msc. ADAMS software.
3D wrist bone models are taken from
anthropometric database of ADAMS
/Lifemodeler Sex Male Age 360 months
Height 1778 mm Weight 77 kg
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BONES
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Motion Analysis of the Wrist Bones
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• Contacts and jonts between
• the wrist bones are analyzed
• Joints are taken as spherical joints.

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JOINT-LIGAMENT-CONTACT MODEL
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LIGAMENTS
Stiffness Coefficient
Damping Coefficient
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52 different ligaments with different stiffness
and damping coefficients are used in the model
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JOINTS
BUSHING ELEMENTS
20 bushing elements (joints) are used in the
model (Coordinates are local coordinates of the
bushing elements)
In the model, rotational spring and damper
coefficients are 1 of translational spring and
damper coefficients.
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CONTACT
Penetration distance
e gt 1 ? stiffening stiffness e lt 1 ? softening
stiffness
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JOINT-LIGAMENT-CONTACT STRUCTURE
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FLEXION MOTION
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EXTENSION MOTION
The model gives correct results for flexion but
for extension limit is exceeded
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RADIAL DEVIATION MOTION
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ULNAR DEVIATION MOTION
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AXIAL LOADING
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20
20
60
50
30
20
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CONCLUSION FUTURE WORK

• For flexion, extension, radial and ulnar
  deviation motions a different
• analysis and a model will be developed
• Joint and ligament variables (stiffness
  damping coefficients) will be
• revised for each different model
• Surface discontinuities on the bones causes
  errors in the results
• More accurate bone structures will be taken
  from CT data

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THANK YOU