VIRTUAL ARTHROSCOPIC KNEE SURGERY TRANING SYSTEM

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VIRTUAL ARTHROSCOPIC KNEE SURGERY TRANING SYSTEM

• Yang Xiaosong
• The Chinese University of Hong Kong
• Tsinghua University

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VIRTUAL ARTHROSCOPIC KNEE SURGERY TRANING SYSTEM

• A joint project between
• the Chinese University of Hong Kong
• Tsinghua University,
• sponsored by
• The National Natural Science Foundation of China
  RGC of Hong Kong

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Minimally Invasive Microsurgical Technique

• Less trauma
• Reduced pain
• Quicker convalescence

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Restrictions of Arthroscopy

• Restricted vision
• Poor hand-eye coordination
• Limited mobility of surgical instruments

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Surgical Skill Training

• Animals
• Cadavers
• Virtual reality based simulation systems

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Arthroscopy Surgery
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Virtual Arthroscopic Knee Surgery Training System

• Modeling using data from Visible Human Project
• Simulation of the deformation of soft tissue with
  topological change by FEA
• User interaction
• Force feedback

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Hardware System Architecture
Central Computer (PIV 1.5G, Nivdia Geforce 3,
Windows 2000)
Input Device
Display Screen
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Software System Architecture
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Mesh Generation of Human Organs

• Segmentation
• Surface boundary meshes creation
• Tetrahedral mesh generation
• Mesh smoothing

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Collision Detection

• Prevent the arthroscope and operation facility
  from entering a solid object
• Get the initial intersection point for cutting
  simulation
• Collision detection for deformable objects,
  different from that of rigid objects
• AABB tree

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Simulation of Soft Tissue Deformation With
Flexible Cutting

• Physically reality
• Real-time interaction

Hybrid Finite Element Method
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Hybrid FEM

• Non-linear deformation and topology changing
  model in operating region (Region 1).
• The local small region, fast to compute
• Linear deformation and topology constant model in
  non-operating region (Region 2)
• The remaining large region, accelerated by
  pre-processing

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2-Dimension Sample
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Cutting of a single element
Degeneration cases
Normal Cases
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3-Dimension Example

• A simplified model of thigh
• Tetrahedral meshes simplification

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Input Device

• Four DOFs for arthroscope and instruments
• Pitch
• Yaw
• Insertion
• Rotation
• Force feedback
• Three DC motors attached for the first three DOF
• The fourth DOF need no force feedback

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Input Device Picture
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System Interface
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Sample
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Work to do

• More effective interactive 3-D segmentation
  system
• Realistic Rendering
• Simulation of complicated operation facilities

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Tetrahedral Mesh Generation of Human Organs on
Segmented Volume
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Tetrahedralization Algorithm on Segmented Volume

• Voxel-Split tetrahedralization
• 3D conforming Delaunay tetrahedralization
  algorithm
• Feature point based tetrahedralization

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Voxel-Split tetrahedralization

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Voxel-Split tetrahedralization
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Voxel-Split tetrahedralization
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Voxel-Split tetrahedralization
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Voxel-Split tetrahedralization

• Simplification of Segmentation Volume

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Voxel-Split tetrahedralization

• Global Simplification of Segmentation Volume
• Boundary voxel decomposition
• The order of voxel merge

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3D conforming Delaunay tetrahedralization
algorithm
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Tissue boundaryextraction
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3D conforming Delaunay tetrahedralization
algorithm

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Feature point based tetrahedralization

• Accurate.
• Small scale.
• Well-shaped.

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Feature point based tetrahedralization

• Placement of the mesh vertices
• Delaunay Triangulation
• Restore the tissue boundary and set element