Use of Grafts & Alloplastic material in

Maxillofacial Trauma

Contents

Introduction Bone grafts Cartilage grafts Muscle grafts Skin grafts Nerve grafts Vessel grafts Fat grafts Alloplastic graft materials Conclusion References

Introduction

Head and neck reconstruction is a special challenge in the field of oral and

maxillofacial surgery and plastic surgery. With the advancements in the

field of oral and maxillofacial surgery , head and neck surgery for various

pathologies and deformities there is increase demand of oromandibular

reconstructive has been arising.

The modern day oral and maxillofacial surgeon needs hard tissue grafting

procedures to meet patient needs in reconstructive surgery involving

trauma, pathology , cleft and craniofacial deformities, orthognathic

surgery, aesthetic surgery, and dental implants.

Introduction to Grafts

The gold standard for bony reconstruction in the maxillofacial region is

currently the use of autogenous bone.

There are certainly other biomaterials available for use in the maxillofacial

region, including banked bone, ceramics, bioactive glass, and bovine bone,

to give some examples.

Bone grafts

When faced with a patient who requires reconstruction of significant hard tissue losses of the mandible, bone grafting is the most viable treatment option.

Principles of bone induction and conduction have been studied extensively over the years.

The graft must be able to provide a source of viable osteogenic cells, such that it maintains sufficient osseous bulk and resists resorption for subsequent prosthetic rehabilitation.

It must also acts as a precursor for bone production and maturation by the bone induction principle. The graft must physically correct any facial form deficiencies resulting from underlying hard tissue losses.

BONE GRFATING BIOLOGY

Cancellous grafts are revascularized more rapidly than cortical grafts.

Cancellous bone incorporates by an appositional phase followed by a resorptive phase but cortical grafts incorporate by a resorptive phase followed by an appositional phase (creeping substitution).

Cancellous grafts tend to repaircompletely whereas cortical grafts remain a mixture of necrotic and viable bone.

TYPES OF BONE GRAFTS

SOURCE

AUTOGENOUS GRAFTSALLOGRAFTS

XENOGRAFTSXENOGRAFTS

DONOR SITE

HISTOLOGIC ARCHITECTURE

cortical bone, cancellous bone

combination of the two

EMBRYOLOGIC ORIGIN

endochondral membranous

BLOOD SUPPLY

free graftfree or regional flap

PRINCIPLES OF BONE GRAFTING:

1.Harvest bone from areas you are familiar with 2. Contour bone graft to fit defect 3.Fix bone graft to defect in a tension-free manner 4.Ensure absolute immobilization static v/s dynamic zones 5.Differentiate between child and adult grafts 6.Avoid contaminated sites 7. Do not graft exposed 8.Ensure adequate blood supply over graft 9. Do not compromise 10.Assess graft “take” periodically.

Regional Donor sites for bone grafts

Somsak Sittitavornwong, Rajesh Gutta. Bone Graft Harvesting from Regional Sites. Oral Maxillofacial Surg Clin N Am 22 (2010) 317–330.

Distant Donor sites for bone grafts

Cartilage grafts

Muscle grafts

Joshua W. Trufant, Sean Marzolf, Brian C. Leach, Joel Cook. The utility of full-thickness skin grafts (FTSGs) for auricular reconstruction. Journal of the American Academy of Dermatology, Volume 75, Issue 1, July 2016, Pages 169-176

Comparison of similar helical defects repaired with the

combination of a cartilage graft and 2-staged mastoid flap (A to C)

versus

repair with full-thickness skin graft alone (D to F).

The end aesthetic outcome is nearly identical with no penalty for

the simpler repair.

Skin graft take and healing

Four phases:

1. Adherence

2. Plasmatic imbibition

3. Revascularization

4. Remodelling

Heather Le Cocq, Paul R.W. Stanley. Closing the gap: skin grafts and flaps. Surgery (Oxford), Volume 29, Issue 10, October 2011, Pages 502-506

Nerve grafts

Chewing food Swallowing Shaving Applying lipstick,

make-up Kissing Drinking fluids Speaking Washing Tooth brushing Playing wind musical

instruments

Common orofacial functions that are interfered with by lost or altered sensation from peripheral trigeminal nerve injuries Algorithm for the management

Great Auricular Nerve (GAN) - neck for nerve gaps of less than 3 cm

Sural nerve (SN) – longer nerve gaps

Size of Donor Nerve Grafts Relative to Injured Nerve

Donor Nerve

Injured Nerve

Sural(2.1 mm)

Greater Auricular(1.5 mm)

Greater AuricularCable (3.0 mm)

Inferior alveolar

(2.4 mm)88% 63% 125%

Lingual (3.2 mm) 66% 47% 94%

Adapted from Brammer JP and Epker BN.

Internal neurolysis:

Nerve stump preparation

Neurorrhaphy

8-0 monofilamentnonresorbable nylon suture

Incomplete eye closure Drooling Speech difficulties Nasal airway

obstruction Cosmetic problems

Problems associated with

facial nerve injury

FACIAL NERVE REPAIR• Primary Repair and Cable Grafting• Cross-Facial Nerve Grafting• Crossover Grafts

DYNAMIC RECONSTRUCTION TECHNIQUES• Regional Muscle Transfer - temporalis• Other Regional Flap Options• Free-Muscle Transfer

STATIC RECONSTRUCTION TECHNIQUES• Brow lifts• Gold weight lid loading• Nasal lateralization procedure• Static sling procedure• Cheiloplasty

FACIAL REHABILITATION• Physiotherapy

Facial nerve static reconstruction. (A) Patient status after resection of malignant right parotid tumor with complete right facial paralysis. Note he significant facial ptosis. (B) Patient status after right browlift, placement of gold weight right upper lid, right commissure of the lip suspension.

Vessel grafts

The first and second sutures are performed 180° from each other. The third suture is placed between the first two while holding the vessel on both sides with the tails of the first and second sutures. After interrupted sutures are placed on one side of the vessel, the microvascular clamps are turned to expose the other side of the anastomosis and proceed in a similar fashion as on thefirst side.

Fat grafts Areas traditionally used for harvesting autologous fat include

the abdomen, flank, gluteal region, thigh, and medial knee. Less common sites include the buccal fat pad and

infratemporal fossa.

Three primary arcs:(1) Lateral cheek projection from the tarsus down to the lower

face,(2) Along the jawline on each side from the lateral mandible to the

mentum, (3) On the forehead and continuing into the convexity of the brow.

Coleman cannulas: (A) No. 1, most blunt tip; (B) No. 2, intermediate tip; (C) No. 3, least blunt tip

• 1 to 3 mL of anesthetic is used for each milliliter of fat to be aspirated.

• Normalize oncotic pressure by adding 1 to 2 mL of human albumin to the 10-mL syringe before harvesting the fat.

3100 rpm for 2 minutes

Centrifuged fat showing three layers: supranatant layer of

triglycerides/oil, middle layer of fat, and infranatant (blood, fluid).

0.05 to 0.1 mL of fat per parcel

Suzan Obagi. Autologous Fat Augmentation for Addressing FacialVolume Loss. Oral Maxillofacial Surg Clin N Am 17 (2005) 99 – 109.

Alloplastic graft materials

Significant advances in materials science and engineering during the latter

half of the 20th century have made the internal use of alloplastic implants

an integral part of many primary and secondary facial procedures.

Their use can also be traced to the simultaneous development of broad

spectrum antibiotics, an improved understanding of the healing of bone

and soft tissues, and the remarkable tolerance of well-vascularized facial

tissues to alloplastic materials.

Alloplastic materials can be described by the term synthetic, indicating that

they are manufactured from nonorganic sources.

Wound healing withalloplastic graft materials

The end-stage healing response to most biomaterials is the formation of an enveloping fibroconnective tissue scar or fibrous encapsulation.

1. Chronic inflammation2. Granulation tissue development3. Foreign body reaction4. An enveloping fibrosis

Almost all biomaterials implanted in the face develop a surrounding fibrous scar, with the one exception of metallic plates used for bone fixation, which can develop bone attachment directly to the implant.

Principles of facial alloplastic material selection and surgical placement

1. Biocompatibility2. Biomaterial is appropriately matched to the tissue plane within which

it will be implanted3. Vascularity and adequacy of soft tissue coverage4. Local tissue infection5. Thickness of overlying soft tissue6. Size of implant7. Fixation of implants to the most stable adjacent structure8. Appropriate use of antibiotics9. Hydrophilic and hydrophobic properties of graft materials10. Handling of graft with all aseptic precautions

Dimethylsiloxane (silicone)

The only noncarbon chain polymer used in medical implantation devices.

Parasymphysis; inferior border and mandibular ramus (angle); paranasal, infraorbital, maxillary, and malar sites; orbital floor and globe; nasal dorsum and columella; and ear.

1. Easy to sterilize by steam autoclaving or irradiation

2. Easily modified intraoperatively3. Retains its flexibility through a

wide temperature range4. Stabilized by suture or screw

fixation5. Economical

6. High degree of chemical inertness

7. Hydrophobic8. Extremely resistant to

degradation9. No tissue ingrowth or

attachment

Polytetrafluoroethylene

Because of the lack of crosslinking in its molecular structure, it is very flexible and has a low tensile strength.

Since 1975 - Vascular prosthes, in abdominal and thoracic surgery applications.

PTFE was originally introduced in facial surgery in the 1980s as a skeletal augmentation material known as Proplast.

The fibrillar composition results in noninterconnected surface openings with pore sizes of 10 to 30 μm.

Can’t be used for TMJ prosthesis.

Polytetrafluoroethylene

Since 1994 - subdermal implantation in the lip, nasolabial folds, glabella, nasal dorsum, and other subcutaneous facial defects; as slings for ptotic tissues of the eyelid and face; and for bony augmentation of the midface, malar, and mandibular areas.

Compressive strength can be improved by adding layers (eg. Block form) Provides ease of removal.

POLYETHYLENE It is available commercially in three major grades:

low-density, high-density, and ultrahigh-molecular-weight polyethylene.

Intramaterial porosity with a pore size between 125 - 250 μm, which permits extensive fibrovascular ingrowth throughout the implant.

HDPE can be shaped intraoperatively with some difficulty.

It accepts drilling and fixation techniques without fracture.

Care should be taken when placing the material immediately underneath a thin soft tissue cover

POLYESTERS

Wide range of shapes (e.g., suture, mesh, vascular conduits,

plates, screws) and sites of tissue implantation, with physical

properties that extend from resorbable to permanent

implants.

They are composed of large, linear, aromatic (permanent)

or aliphatic (resorbable) thermoplastic polymers created by

the establishment of ester linkages between the carbon

bonds.

Polyethylene Terephthalate

synthetic meshes such as Dacron and Mersilene

Onlay facial and nasal augmentation material, genioplasty procedures.

fibrous ingrowth and its soft flexible nature, fixation to the implantation site without palpable edges is usually ensured.

Use of PET mesh in areas of thin overlying skin (e.g., nose) should be avoided.

Available in a mandibular reconstructive tray or as a sheet for cranial coverage, it provided a porous material for bone graft containment or defect coverage.

Resorbable Polymers The aliphatic polyesters are the most widely used class of

resorbable polymers in surgery, and the poly(α-hydroxy) acids (PHAs), consisting of six-membered lactone rings known as lactide and glycolide, comprise most resorbable implantable devices commercially sold.

This copolymer combination combines the more hydrophilic and rapidly resorbing PGA with the more hydrophobic and very slowly resorbing PLA to produce workable fixation devices that maintain strength long enough for craniofacial bone healing (6-8 weeks).

Dexon suture (pure PGA, Davis & Geck, Wayne, NJ) in 1971

Vicryl [90% PGA, 10% PLA], Ethicon, Somerville, NJ)

Monocryl (polyglecaprone 25, a glycolide and ε-caprolactonecopolymer, Ethicon)

1996 - 82% PLA and 18% PGA (LactoSorb, Walter Lorenz Surgical,Jacksonville, FL)

POLYAMIDE

Polyamides are derivatives of nylon that are chemically related to the polyester family of materials. They are best known clinically as a mesh material (Supramid, S. Jackson. Alexandria, VA).

They are very hydroscopic, are structurally unstable in vivo, and undergo hydrolytic degradation & is degraded with a mild foreign body reaction.

They were once used for nasal contouring and augmentation genioplasty, but clinical experience demonstrated that fibrosis and resorption of the material occurred over time.

Although still used by some surgeons for orbital floor reconstruction, this material is now largely of historical interest.

Eppley BL: Alloplastic implantation. Plast Reconstr Surg 104:1761, 1999.

ACRYLIC Acrylic biomaterials are derived from

polymerized esters of acrylic or methylacrylic acids.

greatest use in plastic surgery for cranioplasty procedures in filling full-thickness cranial defects or in secondary fore.

An exothermic reaction results - temperatures can be as high as 80°

Prolo D: Cranial defects and cranioplasty. In Wilkins RH, Rengachary SS, editors:- Neurosurgery, vol. 2, New York, 1985, McGraw-Hill, pp 1647.

Computer-generated cranial implant is composed of sintered hard tissue replacement (HTR) (composite of PMMA and polyhydroxyethylmethacrylate(pHEMA) granules, creating an anatomic prosthesis with interconnected porosity for reconstruction of a large frontal-orbital defect.

Advantages Very low cost Intraoperative fabrication, and

adaptation Can be loaded with antibiotics by

mixing antibiotic powder in the acrylic resin

In the treatment of infected craniofacial fractures and

Reconstructions Can be heated or autoclaved

without change in its physical form

The adjunctive use of metal mesh reinforcement provides more closely approximates the strength of cranial bone

Disadvantages Profound and offensive odor

Allergic reactions

Pregnant females

High cure temperatures require

cool irrigation

Very high bacterial adhesion

property

Thinning of the overlying skin,

implant exposure and infection

ACRYLIC

METALS Since 40 yrs - repair and reconstruction of craniofacial and upper

extremity skeletal injuries, and as an adjunct to oral and craniofacial prosthetic rehabilitation.

The biocompatibility of metal implants is primarily determined by their surface properties and corrosion resistance.

After implantation, an oxide layer quickly forms on the metal’s surface that determines its resistance to corrosion and the amount of leaching of metals or oxides into the adjacent tissues.

The combination of corrosion and metal ion release may cause pain and localized tissue reactions around the implant, necessitating its removal.

Stainless steel, Vitallium, Titanium and Gold

Stainless steel

Alloy of iron, nickel, and molybdenum, with a surface layer of chromium oxide

Have a higher corrosion potential, have a greater amount of metal ion release, and are more likely to require secondary removal.

Nickel - allergic reactions

Vitallium Introduced in the 1930s.

Cobalt-chromium alloy that has strength comparable to that of stainless steel.

It also forms a chromium oxide surface layer, it is much more highly resistant to corrosion than stainless steel due to the higher concentration of chromium in the alloy.

Radiographic imaging and artifact scatter - lost favor for most craniofacial indications

Titanium

Pure material - titanium allergy, toxicity or tumorigenesis.

An alloy - Ti-6a-4v: 6% aluminum an 4% vanadium), which improve the strength

Titanium oxide surface layer - very adherent and highly resistant to corrosion, and even if the oxide layer is damaged, it reforms in milliseconds.

Low density - minimal x-ray attenuation, no artifact on CT or magnetic resonance images.

Gold

Does not develop a layer of oxide

Lack of strength

It has one surgical use as an upper eyelid implant for the treatment of

acquired ptosis in facial nerve palsies

Weights between 0.6 and 1.6 g

CALCIUM PHOSPHATE

Bioactive - osteoconduction Potential for tissue ingrowth and integration into the

recipient site Very well tolerated, with essentially no inflammatory

response, minimal fibrous encapsulation, and no negative effects on local bone mineralization

Ceramic hydroxyapatite - Dense granules or blocks Nonceramic – powder and liquid mixtures

CALCIUM CARBONATE Cranioplasty material (bone cement) Porous and adhesive mixture

Mixing of three components: two castor oil–derived fatty acids (prepolymer and polyol) and a calcium carbonate powder.

Interaction of the fatty acids- release of calcium dioxide - material’s porosity and expands the volume - very liquid to a firm solid.

The second liquid phase, which lasts 4 to 8 minutes after mixing, makes it possible for the material to be injected through small-bore tubes or needles.

Once polymerized - predominantly closed pore (cell) scaffold - bonelike rigidity and strength.

CYANOACRYLATE First described in 1949 - synthetic cyanoacrylate

derivatives for nonmedical uses.

Adverse tissue reactions result from the by products of cyanoacrylate polymer degradation: cyanoacetate and formaldehyde.

However, dermal suture support is still needed.

butyl-2-cyanoacrylate (Histoacryl)octyl-2-cyanoacrylate (Dermabond)

enough to cover 15-20 cm of wound closure

MANAGEMENT OF ALLOPLASTIC INFECTION

1. Migration2. Extrusion3. Palpability4. Risk of infection

Adhesion of bacteria to an implanted biomaterial surface

Initial reversible physical phase (i.e., Physicochemical interaction between

bacteria and material surface)

Irreversible cellular phase (i.e., Cellular interactions between bacteria

and material surface)

Reversed by mechanical washing or irrigation

Occurs intraoperatively Early postoperative period

Drainage and removal of the materialIs advised. Reimplantation 3-6 months

later

Conclusion Reconstruction continues to challenge the head and neck surgeon.

Although, no method meets all the requirements, free tissue transfer techniques allow us to more consistently and reliably meet the needs of the patient.

Each donor site has specific advantages and disadvantages. There must be adequate bone and soft tissue to reconstruct the particular defect.

The status of the patient will always play a role in reconstruction selection. If suitable, we believe mandibular reconstruction with vascularized bone provides optimal function and cosmesis.

Successful reconstruction requires thoughtful selection of a donor site tailored to each patient’s needs.

Conclusion We have passed the era when successful oromandibular reconstruction is

judged by survival of the flap or graft.

With flap survival rates exceeding 95%, the focus is now on function and aesthetics.

Objective means to measure functional deficits and postoperative results are available and need to be instituted into meaningful comparative studies.

REFERENCES

1. Peter Ward Booth, Barry L. Eppley, Rainer Schmelzeisen. Maxillofacial Trauma and Esthetic Facial Reconstruction.  Churchill Livingstone, 2003 , 11th edition.

2. Oral and Maxillofacial Trauma, Volume 2. Raymond J. Fonseca,Robert V. Walker Snippet view - 1991 .

3. Miloro, M., & Peterson, L. J. (2012). Peterson's principles of oral and maxillofacial surgery. Shelton, CT: People's Medical Pub. House-USA.

4. WILLIAMS, J. L., & ROWE, N. L. (1994). Rowe and Williams' maxillofacial injuries. Edinburgh, Churchill Livingstone.

5. Fred G. Fedok. Costal Cartilage Grafts in Rhinoplasty. Operative Techniques in Otolaryngology (2008) 19, 267-272.

REFERENCES

6. Eppley BL: Alloplastic implantation. Plast Reconstr Surg 104:1761, 1999.

7. Suzan Obagi. Autologous Fat Augmentation for Addressing Facial Volume Loss. Oral Maxillofacial Surg Clin N Am 17 (2005) 99 – 109.