titanium in biomedical

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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