titanium in biomedical
TRANSCRIPT
Keith Jackson Technical Director
ZUUDEE
Titanium in Biomedical Applications
Requirements for Medical Devices
Reduce pain
Increase mobility
Correct abnormality or deformity
No adverse biological response
Reliable performance
Strength
Long service life
Titanium in Biomedical Applications
Titanium Properties
High strength
Fracture toughness
Low modulus
Low weight
Corrosion resistance
Biocompatible
Non magnetic
Julius Wolff German Anatomist 1836 - 1902
Julius Wolff German Anatomist 1836 - 1902
Bone is deposited and resorbed
in accordance with the stresses placed upon it.
Wolff’s Law
Wolff’s Law
Friedrich Pauwels 1885 -1980
Cells subjected to stress and strain
differentiate into fibroblasts and chondroblasts
Pauwels’ Theory
Bone Remodelling
Bones are constantly remodelled by osteoblasts and osteoclasts
Implants much stiffer than bone will bear more of the load, reducing stress in the bone.
The body will respond by increasing osteoclast activity, causing bone resorption.
Cancellous bone is more biologically active and resorbs much more quickly than cortical bone.
Stress Shielding
www.doitpoms.ac.uk
Mechanical Properties
The lower modulus of titanium alloys compared to other implant metals is a positive factor in reducing bone resorbtion.
Ti12Mo6Zr2Fe wrought-F1813
Ti13Nb13Zr wrought-F1713
CP and Ti6Al4V SG powders for coating implants
-F1580
Ti5Al2.5Fe wroughtPart 10-
Ti6Al7Nb wroughtPart 11F1295
Ti6Al4V standard grade (SG) wrought (F1108 specifies SG castings)Part 3F1472
Ti6Al4V ELI wrought (ASTM F620 specifies ELI forgings)Part 3F136
Unalloyed titanium – CP grades 1-4 (ASTM F1341 specifies wire)Part 2F67
Alloy(s) Designation(s)BS 7252 /ISO 5832ASTM
Titanium alloys suitable for medical applications
More than 1,000 tonnes of titanium devices are implanted in patients worldwide every year.
Dental Applications
Titanium is corrosion resistant
Pioneered in the early 1950s by Swedish scientist Per-Ingvar Branemark
Dental Applications
Dental Applications
Maxillofacial and Craniofacial Applications
Cardiovascular Applications
Cardiovascular Applications
Titanium is non magnetic
Cardiovascular Applications
Trauma
Trauma
Trauma
Trauma
Spinal Implants
Spinal Implants
Joint Replacement Implants
More than 1 million hip and knee replacementsperformed world-wide each year
1. INCREASED LIFE EXPECTANCY
By 2050, 25% of the UK population will be over 65
http://www.statistics.gov.uk
Market drivers for improved implant performance
Market drivers for improved implant performance2. HEAVIER PATIENTS
3. EARLIER SURGICAL INTERVENTION
typical historic patient > 65 years (1 million steps/year)
younger patients demand:increased survivorship 20 – 40 yearsand optimised function
Traditional patients = 20 million steps / lifetime
Young active patients = 200 million steps / lifetime
10 x increase in demand on joint replacement implant compared with older patients
Market drivers for improved implant performance
4. IMPROVED FUNCTION
Increased range of movement
Increased stability
Reduced risk of dislocation
Market drivers for improved implant performance
Titanium Joint ReplacementsConcerns and Challenges
Some cases of fatigue failure due to high loads and millions of loading cycles
Other implant materials provide better bearing surfaces
Titanium is the material of choice for cementless implant fixation, however it is no longer used with bone cement due to the potential for crevice corrosion
Titanium is bioinert so no adverse biological reaction, however fibrous tissue encapsulation can lead to micro-motion, pain and loosening
Surface modification is required to deliver reliable implant fixation in the long-term
Improved implant performance at an acceptable cost
64 year-old man weighing 70 kg
performed strenuous manual labour
forged Ti 6Al V4 alloy
femoral stem size 12mm
Four years after original operation the patient experienced severe pain in the left hip while walking
The implant was well fixed
Fatigue Failure
Metal on Polyethylene Bearing CoupleParticulate UHMWPE wear debris
Activation of macrophages in periprosthetic tissueRelease of cytokine TNF alpha
OsteoclastsOsteolysis
Aseptic Loosening
UHMWPE wear problem
Titanium not suitable as an implant bearing
Titanium not suitable as an implant bearing
Classification of Biomaterials (Osborn 1979)
Bioactive
Bioinert
Biotolerated
CLASSIFICATION
Bonding Osteogenesis
Hydroxy-apatite
Contact Osteogenesis
TitaniumAlumina
Carbon Fibre
Distance Osteogenesis
Bone CementMetal Alloys
TISSUE REACTIONMATERIAL SYMBOL
Classification of Biomaterials (Osborn 1979)
Stainless Steel implantBiotolerated (distance)
Carbon implantBioinert (contact)
H-A.C. Coated implantBioactive (bonding)
HAC
New bone
Surface morphology of Titanium
Tecotex®Computer-generated, photo-etched, 3D surface textures
Porous titanium surfaces
CSTi™ (Cancellous-Structured Titanium™) Porous Coating
Porous titanium surfaces
Furlong® H-A.C. Total Hip Replacement
The First in the Worldimplanted by Ronald Furlong FRCS 1985
Titanium alloy components (Ti6Al4V)
Coated Implant Fixation
• Titanium Alloy Ti-6Al-4V
• Hydroxyapatite Ceramic
• Bilateral osteogenesis
• Chemical bond with bone
• Physiological Fixation
Furlong & Osborn JBJS 73(B)741-5 1991
H-A.C. Coated Titanium
Norwegian Arthroplasty Register Acta Orthopaedica Scandinavica
Supravit® HAC VPS Coating
HAC Coating Cross-section SEM
Ti-6Al-4V
Ti
HAC
ESEM image of bone formation on Supravit®
Field width 0.07mm
Supravit® HAC - Bone Interface
Furlong® H.A.C Femoral StemHistology - Supravit
Furlong® H.A.C Femoral StemHistology - Supravit
Manufacturing Process
Machining
Glazing & Polishing
Ceramic Coating
Metrology
Clean, Pack & Sterilise
Regulatory Affairs• Medical Devices Directive 93/42/EEC for CE Marking.
• ISO 9001:2008 Quality Management System (QMS).
• ISO 13485:2003 QMS for Medical Devices.
• USA Food & Drug Administration (FDA) 21 CFR Part 820.
• ISO 14001:2005 Environmental Management
• BS OHSAS 18001:2007 : Health & Safety Management
Thank you for your attention
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