BASIC PRINCIPLES IN PLASTIC SURGERYDr.YASIR NAIF QASSIM F.I.B.M.S(plastic & reconstructive)

Definitions:

Plastic as a word came from a Greek word plastikos which means remold or reform.

Plastic as an adjective = capable of being shaped or formed.

Is a branch of surgery that deals with remold,repair& restore body parts. Unlike other surgical specialties, plastic surgery is not organized around a specific organ system so it is based on principles rather than specific surgical procedures.It is divided into 2 main parts:

1.Cosmetic(aesthetic)plastic surgery:That deals with reshaping the normal structures of the body to improve the patients appearance e.g. rhinoplasty,abdominoplasty,facelift,…etc.

2.Reconstructive plastic surgery:That deals with repairing or reshaping(reconstructing) the acquired or congenital abnormalities e.g.reconstructing cleft lip,cleftpalate,traumaticwounds,burn deformities,…etc.

WOUNDS

A wound can be defined as a disruption of the normal anatomical relationships of tissues as a result of an injury. The injury may be intentional such as a surgical incision or accidental followingtrauma. Immediately following wounding, the healing process begins.

PHASES OF WOUND HEALING:

1-The inflammatory phase: begins immediately following tissue injury and lasts 2-3 days. Begins at the time of injury; lasts 2 to 3 days.Initially there will be vasoconstriction to achieve hemostasis,then platelet plug forms and clotting cascade is activated, resulting in fibrin deposition.Platelets release platelet-derived growth factor (PDGF) and transforming growth factor β (TGF-β) from their alpha granules, attracting inflammatory cells, particularly macrophages ,then vasodilation occurs and vascular permeability increases (due to histamine, platelet-activating factor, bradykinin, prostaglandins), aiding the infiltration of inflammatory cells into the wound.Neutrophils peak at 24 hours and help with débridement.Monocytes enter the wound, becoming macrophages, and peak within 2 to 3 days.Limited numbers of lymphocytes arrive later.

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2-Proliferative phase:begins around day 3, as fibroblasts arrive,and lasts through week three.Fibroblasts attracted and activated by (PDGF and TGF-β released by platelets and macrophages) reaching peak numbers by day 7.Collagen synthesis (mainly type III), angiogenesis, and epithelialization occur.

3-Remodeling phase:The remodeling phase is the longest part of wound healing and isbelieved to last from 21 days to 1-2 year.collagen accumulation reaches asteady-state, where there is no change in total collagen content. During this time,there is replacement of the random collagen fibrils with organized, cross-linked fibrils. Type I collagen replaces type III until it reaches a 4:1 ratio of type I to type III (that is of normal skin and mature scar tissue).Scars continue to gain strengthover this phase; however, the tensile strength of scars never reaches that found inunwounded skin, approaching approximately 70-80% of normal strength.

TYPES OF WOUND HEALING:

1.Primary healing (primary intention):wound closureby direct approximation, pedicle flap or skin graft within hours of an injury.2-Secondary Spontaneous healing (secondary intention):woundleft open to heal spontaneously by contractionand epithelialization.Contraction results from centripetal force in woundmargin probably provided by myofibroblasts and epithelialization proceeds from wound marginstowards center at 1 mm/day.3-Tertiary healing ( tertiary intention):delayed woundclosure after several days and can occur any time after granulation tissue hasformed in wound.Delayed closure should be performed when the wound is not infected.

Forms of abnormal wound healing:

1-Impaired healing:that occurs due to local and systemic factors.

Local factors Systemic factors

local ischemia.edema.infection.radiation.foreign body.pressure.

D.M.malnutrition.chemotherapy.steroids.smoking.immunocompromized state.aging process.

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2-Excessive wound healing: in a form of keloids or hypertrophic scars.

Keloids: scar tissue that extends beyond the boundaries of the incision or wound, may develop months to a year after injury, and do not resolve spontaneously. Common in ear lobes,presternalarea,shoulders and areas of tension.Hypertrophic scars: scar tissue that does not extend beyond the boundaries of the incision or wound,develop within weeks of wounding (during the inflammatory phase), and there is usually some degree of improvement with time.

When analyzing a wound, the options for closure are evaluated beginning with the simplest and progressing up to the more complex option according to the “reconstructive ladder” .

Healing by secondary intention:mostly adopted for small wound,by leaving the wound to heal by itself without surgical intervention apart from local wound care.It depends upon epithelialization and wound contraction provided by myofibroblast.

Direct closure: most preferable method because it use the same skin and tissue of the area with the same coloure and quality but this depends on the availability of the surrounding tissues.When the wound is clean,direct closure is achieved by approximating the wound edges without tension.When the wound is contaminated with irregular margins direct closure should not be done unless the wound is copiously irrigated with normal saline and all the devitalized tissues are debrided.There are many methods of wound debridment:

1.Mechanical:by sharp or blunt excision of the dead tissues.

2.Gauze:wet to dry dressing.

3.Chemicals:like topical enzymes that digest the dead tissues.

On closing the wounds aseptic measures(hand scrubbing,using sterile istruments,hair shaving and clean operative site)should be followed and haemostasis should be secured by(digital pressure,electrocautery,clamping or ligating the bleeding vessel or even by using fibrin glue).

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Antibiotics are indicated in:

a.Presence of gross contamination or surrounding cellulitis.

b.human or animal bites.

c.immunocompromized and diabetic patients.

d.patients with vulvular heart disease to prevent endocarditis.

Methods of wound closure:

A.simple interrupted.

B.vertical mattress.

C.horizontal mattress.

D.subcuticular.

E.half buried horizontal mattress.

F.continuous over and over.

In addition to sutures;staples,surgical tapes e.g. steri-strips,and biological or synthetic materials e.g.cyanoacrylate are used as wound closure materials.

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A graft is a segment of tissue that is completely detached from its original site and blood supply(donor site) and transferred to another new site(recipient site),hence its survival depends on the blood supply of the recipient site.

Classifications:

1-According to the source: a.Auto(homo) graft:taken from the same individual. b.Allo(hetero) graft:taken from another individual but of the same species. c.Xenograft:taken from another species(e.g. animals like pigs).2-According to composition: a.Simple graft:composed of a single type of tissue e.g. skin only, tendon only, nerve only,…etc. b.Composite graft:composed of more than one type of tissue e.g. chondrocutaneous graft(skin and cartilage).

Skin graft:

A piece of skin of variable thickness transferred from the donor site to resurface the recipient site when the primary wound closure can not be achieved due to shortage of adjacent tissues for a reason or another.They could be:1. Full thickness (FTSGs): consist of full thickness skin (epidermis and dermis)2. Split thickness (STSGs):consist of the epidermis and varying degrees ofdermis. They can be described as thin, intermediate,or thick according to the amount of dermis. FTSG provide better texture and colour matching.The sensation and the presence of skin appendages are also better than STSG.

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All skin grafts undergo two contractions: 1-Primary contraction: immediately after removal from the donor site as a result of the elastin in the dermis → thick graft has more primary contraction than thin grafts.2-Secondary contraction: after revascularization in the final recipient location.Itinvolves contraction of the healed graft and is probably a result of myofibroblast activity.

Skin Graft Adherence:

There are two phases of graft adherence. The first is fibrinous deposition and adhesion, begins with placement of the graft on the recipient bed,lasting about 72 hours.The second involves the ingrowth of fibrous tissue and vessels into the graft.

Survival of skin grafts:

Skin grafts survive (take) by 3 mechanisms:a. Serum imbibition:In the first 24-48 hours after grafting,skin grafts passively absorb the nutrients in the wound bed by diffusion.b. Inosculation:By day 3, the cut ends of the vessels on the underside of the dermis begin to form connections with those of the wound bed

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c. Angiogenesis:By day 5-7, new blood vessels grow into the graft and the graft becomes vascularized.

Hence,the requirements for graft survival are:1-well vascularized bed→any avascular recipient site like denuded bone(without periostium),denuded cartilage(without perichondrium),denuded tendon(without paratenon) are contraindicated for skin grafts.2-Contact with the recipient bed→any seroma,hematoma,pus,and lose graft application to the bed can lead to graft failure.3-Clean non infected recipient site→heavy infection especially with streptococci can lead to graft failure.

Harvesting skin grafts:

1-STSG→by free hand knives (e.g. Humby knife, Blair knife, and a simple scalpel) or by power-driven dermatomes (electric Brown dermatome ,air Zimmer dermatome and Padgett dermatome).2-FTSG→by a simple scalpel.

Donor Sites:Split-thickness skin grafts can be taken from any area on the body, including the scalp,the Popular areas for split-thickness graft harvest include the thigh and trunk.The donor site of a split-thickness skin graft generally heals by re-epithelialization in 14-2l days so the dressing which is composed of fine mesh(tull) gauze impregnated with a lubricant e.g antibiotic ointment is left in place for 2-3 weeks without changing unless there are features of infection(persistant pain, bad odour,fever,….).

Full-thickness skin grafts can be taken from the The upper eyelid, postauricular , preauricular, supraclavicular, antecubital,volar wrist and groin skin.The donor area is closed by primary suturing unless the area is large → closed by STSG.

Recipient Sites:The recipient site should be vascular and clean,and the graft is secured in place using sutures or staples.the first layer of dressing sould be non adherent covered by dry gauze and bandging.On the face and trunk, the graft is better to be secured to

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the recipient bed by tie-over dressing. The first post-operative inspection of the skin graft is usually performed between 2–5 days postoperatively.

Meshed versus sheet skin graft:Skin grafts can be meshed using scalpel or mesher to increase the surface area→large area can be grafted in addition to that there is no or very little chance for the hematoma or seroma to be collected underneath the meshed graft but they have pebble appearance(aesthetically less acceptable) and liable to contract on application to a joint area.

In contrast ,sheet graft provide superior aesthetic appearance and has less liability for contruction on application on joint area but the risk of development of hematoma and serome beneath it is more in addition to difficulty in resurfacing large areas.

Skin graft failure is caused by:a.Hematoma/seroma — Hematomas and seromas prevent contact of the graft to the bed and inhibit revascularization. They must be drained by day 3 to ensure “take”.It is the most common cause of graft failure.

b.Infection .

c.Poor wound bed — Because skin grafts depend on the underlying vascularity of the bed, wounds that are poorly vascularized with bare tendons or bone, or because of radiation, will not support a skin graft.

d.Sheer forces separate the graft from the bed and prevent the contact necessary for revascularization and subsequent “take”.

e.Upside down application of the graft.

Cultured skin graft:

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Mainly used to cover large defect when the autologus skin is insufficient e.g. extensive burns.Cultured skin grafts composed mainly of epithelium→non satisfactory mechanical nor aesthetic coverage.

Surgical flaps:A flap is a segment or unit of tissue that has its own blood supply indicated for:

1.Covering recipient beds that have poor vascularity(e.g. denuded bone,denudedcartilage,denuded tendon,…etc). 2.Covering vital structures(exposed nerves,exposed major vessels…etc). 3.Reconstructing the full thickness defects of eyelids, lips, ears, nose, and cheeks. 4.Padding body prominences. 5.When it may be necessary to operate through the wound at a later date to repair underlying structures. 6.providing a functional motor unit using muscle flaps. 7.Providing sensation using sensate flap. 8.controlling infection in the recipient area(e.g.in chronic O.M.).

CLASSIFICATION

I-ACCORDING TO BLOOD SUPPLY:

A.Random flaps:have no specific or named blood vessel incorporated in the base of the flap.Theyderive their blood supply from the dermal and subdermal plexus.

B.Axial flaps: have specific named vascular system that enters the base and runs along its axis.They can be sub classified into:

1.Peninsular axial flaps:that keep both the skin and vessel intact at their base.

2.Island axial flaps:that keep only the vessels intact at their base.

3.Freeflaps:both the skin and the vessels are transected at flap base and transferred from the donor site to the recipient site. They require re-

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anastamosis of the artery and vein with the recipient vessels at the recipient site.

II.ACCORDING TO LOCATION (proximity to the primary defect that needs to be reconstructed):

1.Local flaps: are raised from tissues directly adjacent to the primary defect (in direct contact with the defect).

2.Regional flaps: are raised from tissue in the vicinity but not directly adjacent to the primary defect(no direct contact with the defect).

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3.Distant flaps: are raised from tissue at a distance from the primary defect.The free flaps considered distant flaps.

III.ACCORDING TO THE WAY OF MOVEMENT:A.Pivotal flaps:flaps that rotate abouta pivot point and subdivided into:

1.Rotationalflaps:designed and moved in an arc( curvilinear)manner

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2-Traspositional flaps:triangular or rectangular flaps that move laterally to cover the directly adjacent defect (its movement is not in an arc manner).

3-Interpolational flaps:as the transpositional flaps but there is a bridge of tissue between the flap and the defect(i.e. the flap is not in a direct contact with the defect),so iterpolational flaps are either tunneledunder or passed over intervening tissue to close a defect

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B.Advancement flaps: All advancement flaps are moved directly forward or to one side into a defect without any rotation or lateral movement about a pivot point like the single-pedicle advancement, bipedicle advancement, and the V-Y advancement flaps.

single-pedicle advancement flap

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bipedicle advancement flap

V-Y advancement flap

IV.ACCORDING TO TISSUE CONTAINED(COMPOSITION):

-Skin flap (skin+superficial fascia).-Fascia flap e.g. Serratus fascia flap-Fasciocutaneous(skin +superficial fascia+deep investing fascia)-Muscle flap e.g.temporalis muscle flap.-Bone flap e.g. Fibula flap-Myocutaneousflap(skin+fascia+muscle).-Osseomyocutaneous(skin+fascia+muscle+bone).

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Monitoring of flaps1. Clinical evaluation is the best method of flap assessment.a. Temperature: Should be body temperature.b. Color: Should be pink, neither white nor blue/purple.c. Capillary refill: Should be approximately 2 seconds.d. Point bleeding: Upon introduction of a fine-gauge needle, bleeding should be present. Blood should be red, not purple/blue.e. Firmness: Should be soft, but with some appreciable turgor.

Signs of insufficient arterial supply: Cold ,capillary refill slower than 2 seconds ,slow or absent point bleeding and softer.Signs of insufficient venous return (venous congestion):Warmer than expected , blue to purple hue , capillary refill faster than 2 seconds (blood pooled in venous system returns rapidly) , brisk point bleeding,with dark blood , tense and swollen.

2.Doppler studies.3.Fluorescein dye.4.Sensors for O2, pH, temperature.

Factors leading to flap necrosis:1.Haematoma collection beneath the flap.2.Tight suturing.3.Tight dressing.4.Kinking of flap pedicle.5.Cool ambient.6.Nicotine,caffeine& other vasoconstrictive agents.7.Technical errors.

Z-PLASTY:Is a technique in which two triangular flaps are transposed and interdigitated with each other to revise and redirect existing scars or to provide additional length in the setting of scar contracture.

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