Total Hip Replacement: Implant Choices

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Total Hip Replacement Implant Choices
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Introduction

• Improvements in durability and compatibility of
  materials for hip replacements
• New designs to help patients of any age
• Choices of hip joint materials
• Metal-on-polyethylene
• Metal-on-metal
• Ceramic-on-ceramic
• Ceramic-on-polyethylene

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Total Hip Replacement

• The goal is to reduce hip pain and improve the
  motion in your hip.
• More than 345,000 people in the United States
  annually undergo hip replacement surgery.

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Anatomy of the Hip

• Ball and socket joint
• Femoral head or ball is at the end of thighbone
  or femur.
• Socket or acetabulum holds the ball.

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Hip Replacement Components

• Acetabular component - consists of two components
• Cup - usually made of titanium
• Liner - can be medical grade plastic, metal or
  ceramic

Cup
Liner
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Hip Replacement Components

• The femoral component (stem and neck portion), is
  made of metal.
• Femoral head is made either of metal or ceramic.
• Stem is shaped to fit into the bone and support
  the new joint.

Head
Neck
Stem
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Choosing an Implant Right for You Important
Factors to Consider

• Range of Motion
• Stability
• Wear resistance
• Lifestyle
• Gender
• Age
• Weight
• Severity of Osteoarthritis disease

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Range-of-Motion(ROM) What is it? Why is it
Important?

• Arc created by bending the limb at the joint
  called flexion
• Allows thigh to flex from 0 to 90 degrees
• Flexion beyond 90 degrees can cause dislocation

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Stability What is it?Why is it Important?

• Amount of resistance to forces causing motion or
  change of position
• Ligaments and muscles create a resistance force
  keeping the ball of the thighbone in contact with
  the hip socket
• Stability is the mechanical goal of the implant.

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Implant Stability

• Flexing beyond 90 degrees may bring the femoral
  neck against the rim of the cup causing
  impingement
• Femoral ball could leave the cup and dislocate

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How to Improve Hip Stability

• Implants with large diameter ball components
  (36mm or greater) provide more stability
• Allows flexion above 90 degrees without
  impingement

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What are Possible Side Effects?

• Larger cups and liners that may require the
  removal of excess healthy acetabulum bone

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Wear What is it? Why is it Important?

• Similar to erosion
• Caused by friction between the femoral head and
  acetabular cup
• May result in particles flaking off
• Immune system attacks particles and potentially
  bone, causing osteolysis
• Implant may loosen and function improperly

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Hip Implant Bearing Materials

• The bearing is the union of the ball and socket.
• Bearings are made from a variety of commercially
  available materials.

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Hip Implant Bearing Materials

• Metal-on-Polyethylene (poly)
• traditional bearing
• Poly cup with a metal ball
• Metal-on-Metal
• All metal ball and cup
• Ceramic-on-Polyethylene (poly)
• Poly cup with a ceramic ball
• Ceramic-on-Ceramic
• Ceramic cup and ball

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Metal-on- Polyethylene Implants
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Metal-on-Poly Overview

• Poly acts as a cushion for the joint
• Shell made of titanium alloy
• Cup made of medical grade cross-linked
  polyethylene
• Long clinical history since 1963
• Not toxic to the body

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Metal-on-Poly Overview

• Inappropriate for patients who recently or
  currently have
• Joint sepsis (infection)
• Insufficient bone stock
• Marked atrophy (weakness)
• Upper femur deformity
• Skeletal immaturity

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Metal-on-Poly Range of Motion

• Wide range of motion up to 90 degrees flexion
• Options available for patients with
• Smaller bone structure
• Smaller stature
• Abnormal hip structure

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Metal-on-Poly Stability

• Accommodate different sizes of femoral heads
• Control over customization of the implant and fit
  in the body
• Increased cup options to optimize joint stability
• Precise insertion, increasing stability

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Metal-on-Poly Wear

• All bearing surfaces wear with time
• Marathon Cross Linked Polyethylene from DePuy,
  exhibits 86 wear reduction vs. traditional
  polyethylene in mechanical tests

Wear Rates Marathon vs. Traditional Poly
Traditional Polyethylene
Marathon Cross Linked Polyethylene from DePuy
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Metal-on-Metal Implants
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Metal-on-Metal Overview

• Ball and liner made of high-standard,
  surgical-grade cobalt chromium alloys
• Not toxic to the body
• Available since 1960s

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Metal-on-Metal Overview

• Appropriate patients may have
• Young and active lifestyle
• Rheumatoid arthritis
• Osteoarthritis
• Post-traumatic arthritis
• Collagen disorders
• Avascular necrosis
• Non-union of femoral fractures

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Metal-on-Metal Overview Cont.

• Inappropriate for patients who recently or
  currently have
• Joint sepsis (infection)
• Insufficient bone stock
• Marked atrophy (weakness)
• Upper femur deformity
• Skeletal immaturity

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Metal-on-Metal Overview Cont.

• Metal-on-metal femoral heads offer
• Low wear
• Resistance from corrosion and wear
• Excellent clinical history- over 100,000
  implanted
• Increased range of motion
• Very hard and resistant to chipping or cracking
• Smaller diameter acetabular designs to conserve
  healthy bone

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Metal-on-Metal Range of Motion and Stability

• Available in large diameter femoral balls (36mm
  or greater)
• Greater range of motion (up to 151 degrees)
• Increased stability
• Lower rate of dislocation

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Metal-on-Metal Wear
Wear Rate Metal vs. Polyethylene

• Wear rates up to 100 times less than
  metal-on-poly bearings in mechanical tests

Traditional Polyethylene
Ultamet Metal on Metal Articulation from DePuy
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Ceramic-on-PolyethyleneImplants
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Ceramic-on-Poly Overview

• Cup made of Marathon cross-linked poly
• Ball made of Biolox Delta Ceramic
• Composite zirconia aluminum ceramic

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Ceramic-on-Poly Overview cont.

• Appropriate patients may have
• Rheumatoid arthritis
• Osteoarthritis
• Post-traumatic arthritis
• Collagen disorders
• Avascular necrosis
• Non-union femoral fracture

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Ceramic-on-Poly Overview cont.

• Inappropriate for patients who recently or
  currently have
• Joint sepsis (infection)
• Insufficient bone stock
• Marked atrophy (weakness)
• Upper femur deformity
• Skeletal immaturity

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Ceramic-on-Poly Range of Motion and Stability

• Available with large diameter femoral ball (36mm
  or greater)
• Greater range of motion (up to 151 degrees)
• Multiple liner options to reduce the potential
  for dislocation

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Ceramic-on-Poly Wear
Fracture toughnessBiolox Delta vs. Alumina

• Marathon Highly Cross Linked Polyethylene
  exhibits 86 wear reduction over standard poly
  liners in mechanical test
• Biolox Delta Ceramic Ball resistant to chipping
  or cracking
• 97 tougher than traditional alumina ceramics in
  mechanical tests
• Smoother femoral ball decreases wear potential

Biolox Delta from DePuy
Conventional Alumina Ceramics
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Ceramic-on-Ceramic Implants
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Ceramic-on-Ceramic Overview

• Ball and cup made of alumina ceramic
• Shorter clinical history
• Not toxic to the body

Not currently available from DePuy Orthopaedics.
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Ceramic-on-Ceramic Overview cont.

• Ceramic femoral heads offer
• Excellent compatibility within the body
• Good mechanical performance
• Very hard and scratch-resistant
• Chemical and temperature stability

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Ceramic-on-Ceramic Overview cont.

• Appropriate patients may have
• Young and active lifestyle
• Rheumatoid arthritis
• Osteoarthritis
• Post-traumatic arthritis
• Collagen disorders
• Avascular necrosis
• Non-union of femoral fractures

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Ceramic-on-Ceramic Overview cont.

• Inappropriate for patients who recently or
  currently have
• Joint sepsis (infection)
• Insufficient bone stock
• Marked atrophy (weakness)
• Upper femur deformity
• Skeletal immaturity
• Osteoporosis

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Ceramic-on-Ceramic Range of Motion

• Large diameter femoral balls
• Reduced range of motion (133 degrees)
• Increased stability
• Larger diameter femoral balls require larger
  diameter acetabular shells
• 36mm ball requires a 58mm shell

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Ceramic-on-Ceramic Stability

• Intolerance to any impingement of the neck
  against rim of the cup.
• Emphasis on correct implant placement, especially
  in younger patients
• Potential for neck and rim impingement with
  reduced range of motion
• Severe impingement may cause a fracture,
  requiring revision surgery

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Ceramic-on-Ceramic Wear

• 100-200 times less wear rate than other materials
  in mechanical tests
• Resistance to deformation and surface scratching
• Less particle debris around joint available to
  get into the body

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Bearing Summary - Choices

• Surgeons choose a bearing based on durability,
  level of performance, wear resistance and your
  personal needs.
• All of todays bearing materials offer the
  potential for excellent performance.
• No one material is right for every patient.
• Only your surgeon can determine whats right for
  you.
• And whats right for you may not be right for the
  next patient!

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Benefits to Patient from Surgery

• Return to Mobility
• Restores lifestyle
• Freedom

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Potential Complications and Risks

• Individual results may vary
• There are potential risks and recovery can take
  time.
• The performance of any new joint will depend on
  your weight, activity level, age and other
  factors.

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Questions?

• Thank You!