ALLOPLASTIC MATERIALS IN PLASTIC SURGERY

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ALLOPLASTIC MATERIALS 

IN PLASTIC SURGERY 

David Leshem M.D. 

DEPARTMENT OF PLASTIC SURGERY 

TEL AVIV SOURASKY MEDICAL CENTER 

January 2001 

ALLOPLASTS – DEFINITIONS 

• Foreign, non-autogenous materials implanted into tissues for purpose of 

augmenting, reconstructing or replacing tissues, organs or functions of the 

body. 

• Does not depend on local tissues for survival. 

• Temporary implants must disintegrate gradually within a predictable time 

without the production of non-compatable, harmful disintegration products. 

• Permanent implants must provide maintenance-free function in a 

physiologic environment over the patient’s lifetime. 

• Advantageous because: 1. No donor site morbidity. 

2.Unlimited availability. 

3.No operative time for harvesting the graft.

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Criteria for the IDEAL ALLOPLAST (Scales) 

1. Not physically modified by soft tissue. 

2. Chemically inert. 

3. Elicits no inflammatory or foreign body reaction. 

4. Non-carcinogenic. 

5. Produces no state of allergy or hypersensitivity. 

6. Resists mechanical strains. 

7. Capable of fabrication in the form desired. 

8. Sterilizable. 

9. Effective in its intended application. 

10. Temporary (degradable) implants must resorbe in 

predictable non-toxic fashion. 

Biocompatibility (Williams) 

“A state of affairs when a biomaterial exists 

within a physiologic environment without 

either the material adversely and 

significantly affecting the body, or the 

environment of the body adversely and 

significantly affecting the material.”

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Mechanical properties 


• Elastic: X-Y 

• Plastic: Y-F 

• D: Permanent deformation 

• U: Ultimate strength 

• F: Ultimate failure

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• Brittle - Ceramics 

• Ductile - Metals 

• Rubbery - Polymers 

Bone – intermediate 

(ceramic & polymer) 


• Load – static or cyclic 

• Fatigue curve – 

interplay load repetition 

• Endurance limit – load 

below applied repetitively 

without failure.

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• Toxicity 

• Immunogenicity 

Biologic properties 

• Carcinogenicity (Solid state Carcinogenicity theory) 

• Efficacy 

• Potentiation of infection 

• Porosity and tissue ingrowth 

ALLOPLASTIC IMPLANT CONSIDERATIONS 

TISSUE BED 

• Tension of soft tissue closure 

• Thickness of overlying soft tissue 

• Mobility of surrounding tissues 

• Vascularity of recipient site 

• Adequacy of pocket dissection 

• Proximity to bacteria-laden cavities 

• Exposure to mechanical loading

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ALLOPLASTIC IMPLANT CONSIDERATIONS 

IMPLANT CHARACTERISTICS 

• Flexibility 

• Hardness 

• Surface texture 

• Porosity 

• Antibiotic absorption 

• Ease of material contouring 

• Adaptability to recipient site 

• Implant fixation 

TECHNICAL CONSIDERATION WHEN 

IMPLANTING ALLOPLAST 

• Ensure medical acceptability & quality controlled material. 

• Suitable mechanical properties for role. 

• Avoid chemical sterilization. 

• Avoid sharp edges and corners. 

• Stable tension free tissue coverage. 

• Avoid hematoma or dead space in recipient pocket. 

• Remote incision site. 

• Avoid soiling the implant. 

• Minimal or no implant mobility.

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COMPLICATIONS OF IMPLANTING 

ALLOPLASTS 

• Implant does not fulfill the intended role. 

• Mechanical failure. 

• Infection of implant. 

• Severe or persistent inflammation around the implant. 

• Immune alterations secondary to the implant. 

• Toxicity or carcinogenicity. 

• Exposure and/or extrusion. 

• Excessive capsule formation. 

• Capsular contracture.

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CLASSIFICATION OF ALLOPLASTS 

By composition 

• Metals Corrodible -stainless steel 

Noncorrodible -vitallium 

-titanium 

• Polymers Nonelastomeric -polyamide 

-polyesters 

-polyethylenes 

-polyurethanes 

-polymethylmethacrylate 

-polypropylene 

Elastomeric -silicones 

• Ceramics -tricalciumphosphates 

-hydroxyapatite 

CLASSIFICATION OF ALLOPLASTS 

By resorbability 

• Resorbable 

• Nonresorbable 

By Origin 

• Natural 

• Synthetic 

• Semisynthetic

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METALS 

• Uses: skeletal application 

skin staples 

suture 

• Biocompatability: release of ions – toxicity 

• Saline environment – corrosion 

• Oxide layer – resistance to corrosion 

• Corrosion – pain and tenderness, possible 

erythema and sinus tract 

STAINLESS STEEL 

• Alloy – iron, nickel, molybdenum, 

chromium oxide. 

• Annealed – ductile (plastic deformation) 

• Cold worked – stronger

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Advantages 

STAINLESS STEEL 

• Extensive experience 

• Easily fabricated 

• Readily available 

Uses 

• Plates 

• Screws 

• K wires 

Disadvantages 

• Corrosion (removal 2-5y) 

• Annealed easily 

deformed 

• Scatter on CT scan 

STAINLESS STEEL

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VITALLIUM 

Alloy – chromium, cobalt 

Advantages 

• Corrosion resistant 

• Fatigue resistance 

• Strength 

• Little scatter on CT scan 

Disadvantages 

• Brittle 

• Premature fracture 

Uses 

• Fracture plates (Luhr mandibular compression and 

miniplates) 

TITANIUM 

• Pure – element 22 (grade 1-4) 

• Alloy – Ti6Al4V (grade 5) 

• Fabrication more difficult then stainless or 

vitalium

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Advantages 

• Strong 

• Light weight 

• Ductile 

• Corrosion resistant 

• Little scatter on CT 

Uses 

• Fracture plates 

• Screws 

• Mesh 

TITANIUM 

Disadvantages 

• Difficult and 

expensive to 

manufacture 

TITANIUM 

• Osseointegrated implants (dental implants) 

• Bone-anchored suturing devices

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OSSEOINTEGRATED 

IMPLANTS 

OSSEOINTEGRATION – Direct contact 

between metal and bone, without a fibrous 

interface, at light microscopic level. 

(Branemark)

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GOLD 

• Gold plate repair of cleft palate - 1565 

• Nobel element - number 76 on periodic table 

• No oxide layer 

• Lack of strength – softness 

• Expensive 

• Upper eyelid weight – 0.6-1.6 gr. (ptosis) 

POLYMERS 

• Polymers – long chins of repeating units 

that can reach massive molecular weights. 

• Mainly used for soft tissue applications

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POLYMERS 

Properties determined by 

• Chemical composition 

• Ester and amide links permit enzymatic 

degradation 

• Linear, branched and cross link – viscosity 

• Length of chain: low mwt – liquid 

increase mwt gel solid elastomer 

Polyethylene 

• Nonresorbable, synthetic, relatively LMWT 

• Manufactured in forms with increasing strength and 

stiffnes: 

low density – LDPE 

high density – HDPE 

ultrahigh density – UHDPE 

• Porous and woven forms allow fibrovascular ingrowth

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Disadvantages 

Polyethylene 

• Solid form difficult to sculpt 

• Mild persistent chronic foreign body 

reaction 

• Not autoclavabel (melts) 

Polyethylene 

Uses 

• Porous solid (Plastipore, Medpor) – 

augmentation implants, orbital floor 

reconstruction. (pore size 100-250m – 

fibrovascular ingrowth). 

• UHDPE – component of artificial joints 

• Marlex – abd. & chest wall recon., superior 

tensile strength. Not autoclavabel.

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Polypropylene 

• Nonresorbable, synthetic. 

• Highly inert. 

• Similar properties of polyethylene. 

• Can be autoclaved. 

Uses 

Woven mesh (Prolene), suture. 

Polytetrafluoroethylene (PTFE) 

• Non-resorbable, synthetic 

• Inert, antifriction and non-adhesive properties 

• Low tensile strength, pliable. 

uses 

• Woven – vascular prosthesis 

– suture coating - antifriction

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Proplast – PTFE combined with fiber, 

increased porosity and tissue ingrowth for 

stabilization. 

• Proplast 1 – graphite 

• Proplast 2 – alumina 

• Proplast HA – hydroxyapatite 


Proplast 

• Augmentation – chin, malar, nose. 

• Black – not for subcutaneous use. 

• Removed from market – biomechanical 

failure and foreign body reaction in TMJ 

reconstruction.

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GORTEX – expanded PTFE 

• Inert, non-allergenic, non-carcinogenic. 

• Low infection rate. 

Uses 

• Sutures. 

• Soft tissue patches. 

• Subcutaneous augmentation materials – lip, 

chin, nasal, malar, forehead and muscle sling. 

• Dura defects. 

Polyurethane 

• Alternating hard (urethane) and soft (polyether) 

segments. 

Uses 

• Meme, Ashley natural Y breast implant – open cell 

PU foam coating for breast implant 

- allow tissue ingrowth in mammary pocket 

and reduced rate of capsular contracture. 

- PU foam fragmented and degraded releasing 

potentially toxic breakdown products. 

- No reports of cancer caused by PU – removed from 

market 1991

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Polyester 

• Most widely used family of biomaterials in 

surgery. 

• Synthetic polymers with repeating carbonoxygen 

esoteric groups. 

• Chemical structure variation – permanent 

Polyester 

Polyethylene terephthalate 

• Most common of the Polyesters. 

• Widely used in the textile industry. 

– resorbable 

• Permits tissue anchoring to smooth substrate. 

• Early fibrous encapsulation with minimal 

foreign body reaction.

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Uses 

Polyester 

• Dacron – arterial prostheses, suture material. 

• Mersilene – abd. & chest wall reconstruction, 

facial onlay augmentation.(genioplasty) 

• Xomed – reinforced with polyurethane, 

craniofacial reconstruction. 

Polyester 

Aliphatic polymers 

• More then 20 years of use. 

• Resorbable – hydrolysis of ester bond 

• Sutures –Dexon (polyglycolic acid) 

–Vicryl (polyglactin–polyglycolic/lactic) 

– Maxon (polyglyconate) 

– Monocryl (polyglecaprone 25)

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Polyester 

LactoSorb – 82% polylactic and 18% polyglycolic acid 

• Bone fixation device. 

• Strength – 6 to 8 weeks. 

• Complete resorption – approx. 1 year. 

Polymethylmethacrylate 

• Non-resorbable, inert synthetic polymer. 

• Hard transparent resin. 

• Prefabricated or shaped at surgery. 

• Exothermic reaction - 80ºc, 8-10 min.

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Advantages 

• Inexpensive 

• Once cured, it can be contoured with burrs. 

• Can be custom prefabricated. 

• Radiolucent. 

• Dureable. 

• Biocompatible. 

• Low thermal conductivity. 


Disadvantages 

• Offensive odor - allergic reaction. 

• High cure temperature – require irrigation. 

• High bacterial adhesion.

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Uses 


• Cranioplasty. 

• Orthopedic surgery – bone cement. 

• Impregnated with gentamicin – infected 

long bone fractures. 


HTR-PMI – Composite: Polymethylmethacrylate and 

Polyhydroxyethylmethacrylate 

• Significant strength. 

• Porosity. 

• Hydrophilicity. 

• Calcium hydroxide coating – negative charge. 

• Preformed craniofacial implant. 

• Extensive fibrovascular ingrowth, limited 

bony ingrowth.

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• Derivatives of nylon. 

Polyamides 

• Nonresorbable inert alloplast. 

• Hydroscopic, unstable in vivo. 

• Degraded, mild foreign body reaction. 

• Supramid – mesh – not in use. 

uses 

• Suture material. 

Polydimethylsiloxane - SILICONE 

• Nonresorbable synthetic polymer containing 

noncarbon chain, repeating - (Si – O) – backbone 

with organic groups (methyl) attached to the 

silicone atom. 

• Silicone – generic name for high MWT polymer 

• Liquid oil, gel or rubber elastomer. 

• Viscosity – length of chain and crosslinking. 

• Silica particles added to rubbery form – increase 

tensile strength.

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SILICONE 

Properties 

• Thermal and oxidative stability. 

• Resistance to weathering. 

• Hydrophobic nature. 

• Low surface tension. 

• Good dielectric strength. 

• Versatility of structural forms. 

• Nonporous – resist tissue ingrowth. 

• Gas or steam sterilized. 

Properties – cont. 

SILICONE 

• Chemically and physically inert – controversial 

• Degrades in water, soil, air and in-vivo. 

• Shell of breast implant – semipermeable – bleeds

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Local reaction to silicone 

Injected liquid silicone oil- 

• Granulomatous reaction locally and 

regional lymph nodes. 

• Chronic infection, tissue breakdown and 

extrusion. 

• Impurities ? Reported in medical grade. 

• Liquid silicone not recommended. 


Silicone gel- 

• Breast implant bleed or rupture – increase 

capsular contracture – Si in capsule. 

• Ab. Found in serum - after rupture. 

• Siliconomas – granulomas after rupture or 

bleed. 

Histology – phagocytic cells – silicone. 

Chronic inflammatory reaction, foreign body 

reaction.

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Silicone elastomer- 

• May cause capsular contracture. 

• Persistent seromas. 

Silicone synovitis- 

• Infrequent severe synovial inflammatory 

response to silicone joint implants. 

• Reaction to fragmented particles. 

systemic reaction to silicone 

• Hematogenous and lymphatic dissemination. 

• Human Adjuvant Disease (HAD) – Miyoshi 1973 

- stimulation of autoimmune mediated illness after 

implantation of foreign body. 

- nonspecific connective tissue symptoms (fever, 

malasie, arthralgia, arthritis, lymphadenopathy, 

ESR, +Rh factor).

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Connective tissue disease- 

• Controversial – whether silicone and CT 

dis. Are related. 

• RA, Scleroderma, SLE, Sjogren’s, Mixed 

CT dis., etc. 

• Scleroderma most commonly associated 

with breast implants. 

• Epidemiologic studies – no risk of CT dis. 


Malignancy- 

• Silicone injected into mice is carcinogenic. 

• No evidence that silicone is carcinogenic in 

humans.

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Uses of silicone 

Silicone rubbers have been implanted every where in 

the body. 

• Orbital floor recon. – Silastic sheets 

• Malar augmentation – preformed implants 

• Maxillary and zygomatic recon. – custom implants 

• Chin augmentation – prefabricated implants 

• Mandibular condyle – silicon blocks (no longer) 

• Ear recon. – custom implants 

• Nasal augmentation - preformed implants and block 

Uses of silicone – con. 

• Breast augmentation and reco. - preformed implants 

• Small joint arthroplasty: hand - preformed implants 

• First stage tendon recon. – silastic rods 

• Cranioplasty & forehead contouring – prefabricated 

implants 

• Tissue expansion - prefabricated expanders 

• Scar revision – silastic sheets

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Properties- 

Ceramics 

• Brittle – minimal deformation per unit force. 

• Strong compressive strength. 

• Weakened by flaws, microcracks and porosity. 

• Highly inert. 

• Used as bone substitutes, not in load bearing 

areas. 

Hydroxyapatite (HA) 

• Most common apatite crystal is calcium HA 

• Synthetic varieties: 

- sintering Ca and P particles 

- dense or porous 

• Natural varieties: 

- porous coralline HA (50-200m) 

• No inflammatory or foreign body giant cell response 

• Bone regeneration by osteoconduction (scaffold) 

• No osteoinduction

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Hydroxyapatite (HA) 

• Bone growth enhanced by fixation of HA 

• HA resorbed after bone regenerated 

Tricalcium Phosphates (TCP) 

• Bone ingrowth (less than HA) 

• Resorbable over time, unpredictable 

• Very inert 

• No advantage over HA

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HA Cement (Paste) 

• Calcium phosphate based (terra & bi CaP) 

• Microporous 

• Resorbable 

• Inlay position 

HA Cement (Paste)

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Bioglass 

synthetic bone graft 

• Silicone, calcium, phosphorous oxide. 

• “Osteoconductive” – scaffold. 

• High osteoblastic activity ? 

• Can be combined with auto and allograft bone. 

• New biomaterials. 

Future 

• Pharmacologic technology – merge 

antibiotics, growth factors etc.

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References 

• Flood J. Implantation:bone, cartilage, and 

alloplasts. Selected readings in plastic 

surgery, volume 9(8), 2000. 

• Barry L. Eppley, Alloplastic Implantation, 

PRS – NOVEMBER 1999. 

• Christine Tang, Alloplastic materials in 

plastic surgery, April 1997. 

THANK YOU!

ALLOPLASTIC MATERIALS IN PLASTIC SURGERY

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