The development of a damage based boneremodelling algorithm

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The development of a damage based
bone-remodelling algorithm

• By Jan Hazenberg

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overview

• Bone
• Hip-implants
• Bone remodeling
• Work done so far
• Further work

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From skeleton to microstructure
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Bone microstructure
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Cortical versus trabecular bone
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Osteocytes and canaliculi
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Hip-implants

• Between 500,000 and 1 million hip implants per
  year
• 65 due to osteoarthritis (insert picture)

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Failure No. 1
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Types of implants

• Cemented
• Patients gt 60 years
• Cements with or without antibiotics
• High and low viscosity cement
• Uncemented
• Patients lt 60 years and exceptions
• Biological coating on the stem

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Success of hip-replacement is depending on
Surgical factors Surgical experience and
skills Patient selection   Prosthetic
factors Prosthetic materials Shape Prosthetic
fixation (cemented or press-fit) Surgical
instrumentation   Patient factors Patient
compliance to surgical instructions Patient
activity Patient weight General health Patient
bone quality and quantity
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Hip-replacement
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Bone remodeling

• Bone a unique material
• Modeling
• Remodeling
• Adaptation

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Basis Multi-cellular Units (BMU)
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Stimuli proposed in literature

• Strain energy density
• Stress
• Strain
• Electrical stimuli
• Chemical stimuli
• Damage (fatigue due to cyclic loading)
• Osteocytes, the living cells in the structure are
  assumed to sense these stimuli.

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EFFECT OF HIP-IMPLANT ON BONE
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CALCULATIONS AND VALIDATION OF FEA
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Modeling the process
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Work done so far 1
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Work done so far 2
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Work done so far 3
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Work done so far 4
MSc. Eoin Bates The effect of fluid on the
stresses around the cracks in bone.
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Approach for the stimulus
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Damage tensor

• Aim is to develop a damage tensor as a function
  of stress and the microstructure (age) of bone.