Title: Total Hip Replacement: Implant Choices
1Total Hip Replacement Implant Choices
2Introduction
- 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
3Total 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.
4Anatomy 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.
5Hip Replacement Components
- Acetabular component - consists of two components
- Cup - usually made of titanium
- Liner - can be medical grade plastic, metal or
ceramic
Cup
Liner
6Hip 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
7Choosing an Implant Right for You Important
Factors to Consider
- Range of Motion
- Stability
- Wear resistance
- Lifestyle
- Gender
- Age
- Weight
- Severity of Osteoarthritis disease
8Range-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
9Stability 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.
10Implant 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
11How to Improve Hip Stability
- Implants with large diameter ball components
(36mm or greater) provide more stability - Allows flexion above 90 degrees without
impingement
12What are Possible Side Effects?
- Larger cups and liners that may require the
removal of excess healthy acetabulum bone
13Wear 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
14Hip Implant Bearing Materials
- The bearing is the union of the ball and socket.
- Bearings are made from a variety of commercially
available materials.
15Hip 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
16Metal-on- Polyethylene Implants
17Metal-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
18Metal-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
19Metal-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
20Metal-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
21Metal-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
22Metal-on-Metal Implants
23Metal-on-Metal Overview
- Ball and liner made of high-standard,
surgical-grade cobalt chromium alloys - Not toxic to the body
- Available since 1960s
24Metal-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
25Metal-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
26Metal-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
27Metal-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
28Metal-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
29Ceramic-on-PolyethyleneImplants
30Ceramic-on-Poly Overview
- Cup made of Marathon cross-linked poly
- Ball made of Biolox Delta Ceramic
- Composite zirconia aluminum ceramic
31Ceramic-on-Poly Overview cont.
- Appropriate patients may have
- Rheumatoid arthritis
- Osteoarthritis
- Post-traumatic arthritis
- Collagen disorders
- Avascular necrosis
- Non-union femoral fracture
32Ceramic-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
33Ceramic-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
34Ceramic-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
35Ceramic-on-Ceramic Implants
36Ceramic-on-Ceramic Overview
- Ball and cup made of alumina ceramic
- Shorter clinical history
- Not toxic to the body
Not currently available from DePuy Orthopaedics.
37Ceramic-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
38Ceramic-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
39Ceramic-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
40Ceramic-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
41Ceramic-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
42Ceramic-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
43Bearing 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!
44Benefits to Patient from Surgery
- Return to Mobility
- Restores lifestyle
- Freedom
45Potential 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.
46Questions?