Massachusetts Institute of TechnologyMassachusetts Institute of TechnologyHarvard Medical SchoolHarvard Medical School

Brigham and Women’s HospitalBrigham and Women’s HospitalVA Boston Healthcare SystemVA Boston Healthcare System

2.79J/3.96J/BE.441/HST522J2.79J/3.96J/BE.441/HST522J

FORMATION OF SOFT TISSUE AND BONE FORMATION OF SOFT TISSUE AND BONE AROUND IMPLANTS:AROUND IMPLANTS:

The Chronic Response to ImplantsThe Chronic Response to Implants

I.V. Yannas, Ph.D. and M. Spector, Ph.D.I.V. Yannas, Ph.D. and M. Spector, Ph.D.

RESPONSE TO IMPLANTS:RESPONSE TO IMPLANTS:WOUND HEALINGWOUND HEALING

Surgical ImplantationSurgical Implantation

Vascular ResponseVascular ResponseClottingClotting

PhagocytosisPhagocytosisNeovascularizationNeovascularization

New Collagen SynthesisNew Collagen Synthesis

Tissue of Labile and Stable CellsTissue of Labile and Stable Cells Tissue of Permanent CellsTissue of Permanent Cells

FrameworkFramework FrameworkFramework ScarringScarringIntact DestroyedIntact Destroyed (fibrous encapsulation;(fibrous encapsulation;

synovium)synovium)RegenRegen. . ScarringScarring Chronic InflammationChronic Inflammation

((incorpincorp. . (fibrous encapsulation;(fibrous encapsulation;of implant)of implant) synovium)synovium)

Chronic InflammationChronic Inflammation

Acute Acute InflammationInflammation GranulationGranulation

TissueTissue

Implant MovementImplant Movement

Inc. timeInc. time

Photo removed due to copyright considerations.

I. Metchnikoff

In 1923 a piece of glass was removed from a patient’s back; it had been there for a year. It was surrounded by a minimal amount of fibrous tissue, lined by a glistening synovial sac, containing a few drops of clear yellow fluid.

Photo removed due to copyright considerations.

Smith-Peterson

J. Bone Jt. Surg., 30-B:59 (1948)

Four pages removed due to copyright considerations.

I. Silver

CHRONIC RESPONSE TO IMPLANTSCHRONIC RESPONSE TO IMPLANTS

•• Persistence of macrophages* at the implant Persistence of macrophages* at the implant surfacesurface

•• Presence of fibroblasts*Presence of fibroblasts*•• Proliferation and increased matrix synthesis of Proliferation and increased matrix synthesis of

fibroblasts can result from mechanical fibroblasts can result from mechanical perturbation by the implant or by agents perturbation by the implant or by agents released by the implant, leading to an increase in released by the implant, leading to an increase in the thickness and density of the scar tissue.the thickness and density of the scar tissue.

•• Fibroblast contraction can result in scar Fibroblast contraction can result in scar contracture.contracture.

* Constituents of synovium* Constituents of synovium

MACROPHAGE AND FIBROBLAST MACROPHAGE AND FIBROBLAST INTERACTIONS IN SYNOVIUMINTERACTIONS IN SYNOVIUM

Macrophage + Part. Sol. Part +Macrophage + Part. Sol. Part + RegReg..EndocytosisEndocytosis

Fibroblast + ECM +Fibroblast + ECM + RegReg..

Fibroblast + ECM +Fibroblast + ECM + RegReg..

Fibroblast + ECM +Fibroblast + ECM + RegReg..

Fibroblast + ECM +Fibroblast + ECM + RegReg..

MitosisMitosis

MigrationMigration

SynthesisSynthesis

ContractionContraction

IonsIons Mechanical forceMechanical force

RESPONSE TO IMPLANTS:RESPONSE TO IMPLANTS:WOUND HEALINGWOUND HEALING

Surgical ImplantationSurgical Implantation

Vascular ResponseVascular ResponseClottingClotting

PhagocytosisPhagocytosisNeovascularizationNeovascularization

New Collagen SynthesisNew Collagen Synthesis

Tissue of Labile and Stable CellsTissue of Labile and Stable Cells Tissue of Permanent CellsTissue of Permanent Cells

FrameworkFramework FrameworkFramework ScarringScarringIntact DestroyedIntact Destroyed (fibrous encapsulation;(fibrous encapsulation;

synovium)synovium)RegenRegen. . ScarringScarring Chronic InflammationChronic Inflammation

((incorpincorp. . (fibrous encapsulation;(fibrous encapsulation;of implant)of implant) synovium)synovium)

Chronic InflammationChronic Inflammation

Acute Acute InflammationInflammation GranulationGranulation

TissueTissue

Implant MovementImplant Movement

Inc. timeInc. time

IMPLANT MATERIALS/BIOMATERIALSIMPLANT MATERIALS/BIOMATERIALSTISSUE RESPONSETISSUE RESPONSE

Soft Tissue (that does not regenerate)Soft Tissue (that does not regenerate)•• Fibrous capsule (scar)Fibrous capsule (scar)

Synovium: fibrous tissue interspersed with Synovium: fibrous tissue interspersed with macrophagesmacrophages

Wound healing response of repair (scar formation) Wound healing response of repair (scar formation) coupled with macrophage accretion at the “dead coupled with macrophage accretion at the “dead space” space” -- chronic inflammationchronic inflammation

BoneBone•• Tissue integration and tissue bondingTissue integration and tissue bonding

TISSUE INTEGRATION TISSUE INTEGRATION TISSUE BONDINGTISSUE BONDING

•• Tissue Integration (Osseointegration)Tissue Integration (Osseointegration)Apposition of tissue (bone) to the implant (contact of Apposition of tissue (bone) to the implant (contact of

bone with the surface but not necessarily bonding); bone with the surface but not necessarily bonding); no macrophage layer?no macrophage layer?

Regeneration of tissue up to the surface of the implantRegeneration of tissue up to the surface of the implant•• Tissue Bonding (Bone Bonding)Tissue Bonding (Bone Bonding)

Chemical bonding of tissue (Chemical bonding of tissue (vizviz., bone) to the surface., bone) to the surfaceProtein adsorption and cell adhesionProtein adsorption and cell adhesionBiomaterials: calcium phosphates and titanium (?)Biomaterials: calcium phosphates and titanium (?)

Dental Implant Designs and Materials

Carbon

TitaniumAlumina

Images removed due to copyright considerations.

Alumina AluminaCarbon

Blade Implant

Photos removed due to copyright considerations.

“Commercially pure” Titanium

Two-Stage Design;to shield the artificial

root from loading during the initial stage of healing

Images removed due to copyright considerations.

Osseointegration

Images removed due to copyright considerations.

T. Albrektsson, et al., Ann. Biomed. Engr., 11:1 (1983) T. Albrektsson, CRC Crit. Rev. Biocompat., 1:53 (1984)

Osseointegration:Control of Surgical Trauma

Image removed due to copyright considerations.

T. Albrektsson, CRC Crit. Rev. Biocompat., 1:53 (1984)

Implants with Porous Coatings in Bone

Bone

Metal stemBone

Beaded porous coating

Image removed due to copyright considerations.

Image removed due to copyright considerations.

Image removed due to copyright considerations. Bone

Hydroxyapatite-Coated Implants

Images removed due to copyright considerations.

Plasma-sprayedHA coating, 40 µm thick

3 hrMetal

Image removed due to copyright considerations.

Bone Image removed due to copyright considerations.

Cylindrical implant in canine

prox. femur

6 da Plasma-Sprayed Hydroxyapatite

Coating

Image removed due to copyright considerations.

14 daImage removed due to

copyright considerations.

Bone regeneration in the gap between the implant surface and surrounding bone.

Plasma-Sprayed Hydroxyapatite Coating14 days

Photo removed due to copyright considerations.