King Suad University College of Engineering Industrial Engineering Department

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King Saud UniversityCollege of
EngineeringIndustrial Engineering Department

• Custom-Made Artificial Knee

By Abdullah AlNuiam Supervised By Prof. Saied
Darwish
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Outline

• Introduction
• Objective
• Artificial Knee joint
• Biomaterial
• Mastercam
• CNC Machine
• G-codes
• Conclusions

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Introduction

• Biomedical engineers have long been working on
  solutions to design a better replacement joints
  to improve the lives of the thousands of patients
  every year
• The design, manufacture and placement of these
  artificial joints require a high degree of skill
  and a thorough knowledge of physics, biology and
  chemistry

Some examples

• Artificial hips, knees and other joints.
• Ultrasound, magnetic resonance imager (MRI) and
  other
• medical imaging techniques.

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Types of joints

• Ball and socket joints

• Gliding joints

• Hinge joints

• Saddle joints

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Knee Joint

• The knee is the largest joint in the body
• Normal knee function is needed to perform routine
  everyday activities
• The most common reason for having a knee replaced
  is osteoarthritis.

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Problem definition

• This project aims to manufacture a custom made
  knee joint locally using MasterCAM to design and
  CNC machine to manufacture.

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Normal Knee

• The knee is the largest joint in the body
• Normal knee function is needed to perform routine
  everyday activities
• It consists of
• Femur which rotate the upper end of the shin
  bone (tibia)
• Tibia which is the shin bone
• Patella (knee cap) which slides in a groove on
  the end of the femur.

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What Is a Knee Replacement?

• The most common reason for having a knee replaced
  is osteoarthritis.
• Knee replacement, is a surgical procedure in
  which the diseased parts of the knee joint are
  removed and replaced with new artificial parts.
• The goals of knee replacement surgery
• include increasing mobility, improving the
• function of the knee joint, and relieving pain.

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Surgical Considerations

• When choosing an implant, the surgeon will
  consider many factors, including the patient's
• Age
• Weight
• Gender
• Anatomy
• Activity level
• Medical history
• General health

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How Are Knee Problems Diagnosed

• Diagnostic tests depend on the findings of the
  medical history and physical exam, such as
• X-ray
• Computerized axial tomography (CAT) scan
• Bone scan (radionuclide scanning)
• Magnetic resonance imaging (MRI)
• Biopsy
• Those tests are needed in designing custom-made
  knee joint they show angles and sizes needed to
  produce a replacement knee that matches this
  human's body structure.

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Injuries

• Osteoarthritis (OA)
• Rheumatoid
• Avascular Necrosis
• Malalignment of Knee Joint

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Project Objective

• The custom-made is the only solution for tumor
  patients .
• Hospitals need to convert the x-ray into solid
  models that can be manufactured.
• The Objective is to test the visibility of
  manufacturing a custom-made artificial knee joint
  locally.
• This is to develop a special design to suit each
  patient with the minimum possible time and
  minimum cost

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Knee Replacement

• The complexity of the knee joint has presented
  special challenges in the design and insertion of
  an artificial joint.
• The knee needs to allow movement from zero
  (straight) to 90 degrees at least.

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Components of Artificial Knee

• Femur (top)
• Tibia (bottom)
• Polyethylene (in between)

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Types of Knee Replacements

• Depending on the degree of mechanical stability
  provided by the design of the artificial knee,
  there are three basic categories of knee
  replacement
• Non- constrained
• Semi- Constrained
• Unicondylar

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Progresses in Knee Replacement

• Technology has led to the development of
  materials used.
• Major advancements in knee replacement have
  greatly improved the outcome of the surgery
• Artificial joint replacement for arthritis of the
  knee is one of the most successful surgeries of
  the last century
• 95 of people are able to begin walking the day
  following surgery and pain relief is achieved.

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Advantages of Knee Replacement

• This operation produces very effective and long
  lasting relief from joint pain
• It gives a joint which functions normally
• The recovery period from the operation is very
  short
• The patient is able to walk from the 2nd or the
  3rd day after the operation.
• The patient regains a normal lifestyle and
  mobility with significant improvement in quality
  of life

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Biomaterial

• Biomaterial are materials used for surgical or
  dental instruments and for external prostheses.
• A biomaterial placed within the interior of the
  body must be biocompatible.
• It should possess adequate physical and
  mechanical properties to serve as replacement of
  body tissues
• It should be amenable to be formed into different
  shapes, have relatively low cost, and be readily
  available

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Biomaterial

• The primary materials used in Total Knee System
  implant components include cobalt chromium
  molybdenum alloy (Co-Cr-Mo)

cross sections of tibia base plate
Cross Section of CO-Cr-Mo formal
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Types of Wear

• Abrasive Wear
• Adhesive Wear
• Fatigue Wear
• Third Body Wear

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Role of Industrial Engineer

• Gather information about joint/bones dimensions
  using x-rays to come up with suitable knee
  replacement sizes
• Develop models for patients come up with an
  appropriate combination of cement thickness,
  offset distance and femoral head size that will
  accommodate the patient's size.
• Implementing CAD/CAM and extracting CNC codes to
  manufacture the appropriate knee replacement for
  Saudi patients
• Predict the durability of the replacement by
  modeling the progress of the wear behavior of
  replaced components

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Mastercam
MasterCAM is a commercial Computer Aided
Manufacturing software package includes a CAD
environment, a geometry-to-G-code translator, and
a G-code simulator. MasterCAM provides full 2D
and 3D design capability for drawing mechanical
parts, and creates output code for programming
CNC
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Advantages of MasterCAM

• Mastercam can build work-holding fixtures,
  complex 3D form fixtures, and to build
  assemblies.
• Mastercam allows for fast and easy development of
  tool paths.
• Fast and easy translation between CAD and CAM
  files.
• You can check your work for errors before the
  actual machining began, saving the time and
  money.

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Manufacturing Process

• The dimensions of the femur of the artificial
  knee joints were measured to get the following
  dimensions

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Procedure of Manufacturing

• 1) The blank for the job is prepared by Material
  cutting, milling and surface grinding.
• 2) The workpiece is WIRECUT in the WEDM machine
  and so is the holder
• 3) The workpiece is machined in the upside-down
  direction to finish all bottom operations with
  material for a screw hole in the center

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Procedure of Manufacturing

• 4) The workpiece is fixed to the holder with the
  screw. The job is held at 45degree to run a CAM
  program generated in that direction.
• 5) The workpiece is than held at another angle of
  -45degree to run another CAM program generated in
  that direction.
• 6) The job is polished to achieve the required
  finish

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Final Shape
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Machine

• The machine used to manufacture this artificial
  femur knee joint was a Huron kx-15 five axis
  machine
• That device is very appreciated for the machining
  of very technical and complex work pieces

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CNC Controller

• CNC stands for "Computer Numeric Control". It's
  referring to machinery that is under automated
  control, as opposed to manually by an operator.

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G-Codes

• What is G-code?

When the designed product is produced using CNC
machine tools, the machine tool controller needs
explicit instructions describing the type and
order of individual steps required to perform a
given task. These instructions are provided to
the controller in the form of alphanumeric codes
(G-code) and are usually called a part program.
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Sample of G-Codes

• (PROGRAM NAME - Knee joint)
• N100G21
• N102G0G17G40G49G80G90
• (UNDEFINED TOOL - 1 DIA. OFF. - 41 LEN. - 1 DIA.
  - 6.)
• N104T1M6
• N106G0G90G54X-101.307Y2.758A0.S50M5
• N108G43H1Z60.
• N110Z-.354
• N112G1Z-5.354F0.
• N114X-101.21Z-5.137
• N116X-101.043Z-4.837
• N118X-100.959Z-4.66
• N120X-100.71Z-4.24
• N122X-100.691Z-4.203
• N124X-100.622Z-4.095
• N126X-100.41Z-3.839
• N128X-100.248Z-3.676
• N130X-100.126Z-3.542

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Sample of G-Codes

• N1178X-37.64Z-7.54
• N1180X-37.614Z-7.595
• N1182X-37.451Z-8.398
• N1184X-37.356Z-8.975
• N1186Z-3.975
• N1188G0Z-2.858
• N1190X-39.326Y48.883
• N1192G1Z-3.886
• N1194Z-8.886
• N1196X-39.808Z-8.589
• N1198X-57.292Z-8.59
• N1200X-57.547Z-8.841
• N1202Z-3.841
• N1204G0Z-3.84
• N1206X-81.326
• N1208G1Z-3.886
• N1210Z-8.886
• N1212X-81.808Z-8.589
• N1214X-99.292Z-8.59

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Tool path for the model
Video of Process
1st set up
2nd set up
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Conclusions

• The present work shows that artificial knee joint
  could be manufactured locally.
• The MasterCAM proved sufficient, not only to
  represent the femur part of the joint, but also
  to generate tool path and G-codes necessary to
  manufacture the femur part of the joint.
• This success will hopefully have a reflection on
  the manufacture of custom-made artificial knee.
  This is expected to help reduce the suffering of
  our patients.

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Thank You
Special thanks to my adviser Prof.
Darwish
King Saud UniversityIndustrial Engineering
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