FLAP CLASSIFICATIONS
Definition: A block of tissue with a functioning circulation that is designed to be
transferred from one part of the body (donor site) to another (recipient area)
Considerations
Vascularity
1. random cutaneous (subdermal plexus)
2. direct / axial cutaneous
3. fasciocutaneous
4. perforator
5. musculocutaneous
6. venous
Circulation
1. random
2. axial
o single artery
o multiple arteries
3. Flow
o orthograde flow
o retrograde flow
Components
1. skin
2. fat
3. fascia
4. muscle
5. bone
6. cartilage
7. tendon
8. nerve
Destination
1. local
2. regional
3. distant
a. random
b. pedicled
c. free
Movement
1. advancement
2. pivot
a. transpose
b. rotate
c. interpolate (including island)
3. turnover
4. distant
5. via carrier (tubed)
6. direct
7. free
Configuration
1. proximal pedicle
2. distal pedicle
3. bipedicled
4. islanded
5. special eg bilobed
Tissue preparation
1. no delay
2. delay
3. tissue expansion
4. prefabrication - implantation of vascular pedicles
5. prelamination - implantation of tissue or other devices into a flap prior to transfer
Flap vascularity
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macrocirculation of skin flaps from 3 sources (Daniel and Williams)
1. segmental
a. considered to be in continuity with the aorta as regards perfusion
pressure
b. generally course deep to the muscles and supply perforators to them,
and are accompanied by a single large vein, often in association with a
nerve
2. perforator
a. vessels that pass through muscles and and connect to cutaneous vessels
3. cutaneous vessels
a. 5 distinct plexi
i. Fascial
ii. Subcutaneous
iii. Subdermal
iv. Dermal
v. Subepidermal
Types of cutaneous territory (Cormack and Lamberty)
a. anatomical territory - This can be dissected out microscopically and is
delineated by the extent to which the branches of that vessel ramify before
anastomosing with adjacent vessels.
b. dynamic territory - This implies that some intervention has taken place
(usually surgical). This event promotes opening up of the anastomotic
channels that the vessel shares with adjacent vessels.
c. potential territory - This is encountered when an otherwise unrelated
cutaneous segment is isolated in continuity with the territory of an adjacent
artery. This is usually accomplished by a delay procedure when a
potential territory incorporates a “random” element of the flap that has
undergone fundamental changes between delay and flap elevation.
Angiosome (Taylor)
a. a composite unit of skin and underlying deep tissue supplied by its
b.
c.
d.
e.
source artery
Adjacent angiosomes are connected by choke vessels
a flap designed on a primary angiosome can reliable carry any adjacent
angiosome. Angiosomes beyond the adjacent angiosome are not generally
reliable unless a delay procedure is performed.
ie in a free TRAM, the primary angiosome is zone 1, and zones 2 and 3 are
the adjacent angiosomes, which are reliable. Zone 4 is two angiosomes
away from the primary angiosome and thus is not reliable.
In a pedicled TRAM, zone 1 is actually the adjacent angiosome and zones
2 and 3 are the angiosomes beyond it. This angiosome principle would
suggest that zones 2 and 3 in a pedicle flap are not reliable.
Random Flaps
Physiology
 Because of its thermoregulatory function, the rate of blood flow through the skin
is one of the most variable in the body.
 At baseline, blood flow to the skin is approximately 10 times that required for
nutritional support.
 It is because of this relative oversupply that random flaps are able to survive.
 Relative blood flow increases after flap is raised due to
1. Local hypoxemia and an increased level of metabolic products induce
precapillary sphincters to open
2. AV shunts - increase in body temperature results in a decrease in
norepinephrine release, which results in closure of the AV shunts and
increased blood flow to the skin.
 surviving length of a random flap does not depends entirely on the width of the
base –
 determined by the perfusion pressure within the arterioles and
intravascular resistance.
 Widening the base of a flap does not affect either of these factors. Thus,
there is no benefit to widening the base beyond a certain point.
 When perfusion pressure falls below the critical closing pressure of an
arteriole, blood flow through that arterial ceases.
 most authors agree that a length to width ratio of 3 or 4 to 1 will result in a
viable random pattern flap on the face or scalp.
 four important concepts
1. stress
 refers to the force applied per cross-sectional area.
2. strain
 refers to the change in length divided by the original length of the given
tissue to which a force is applied
3. creep
 refers to the increase in strain seen when skin is under constant stress
 occurs over a matter of minutes and is due to an extrusion of fluid from the
dermis and a breakdown of the dermal framework.
4. stress relaxation.
 the decrease in stress when skin is held in tension at a constant strain for a
given time.
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occurs over a matter of days to weeks and is due to an increase in skin
cellularity and the permanent stretching of skin components.
 concept of serial excision is based upon the fact that skin closed under
tension will display a certain amount of stress relaxation and creep over
time.
Delay - decreases the incidence of flap failure due to ischemia
 For random flaps, one incises along the long axis of the flap and
undermines without dividing either end of the flap
 For axial flaps, one incises along all margins but the base of the flap (so as
not to cut across the pedicle) without undermining.
Blood Supply
 subdermal plexus or may be axial
Advantages
1. Ideal colour match and composition (local tissue).
2. Good survival because of advantageous size (small!) and orientation.
3. Donor site usually easy to deal with.
4. Useful, especially on the face.
Disadvantages
1. Donor site morbidity.
2. Vascular compromise
3. Limited composition
4. Unreliability as size increases
Principles:
1. use aesthetic junctions
2. hide scars in relaxed skin tension lines
Langers vs RSLT
 Langer diagrams were developed from cadavers in a uniform position, with their
extremities in extension. Langer discovered that his lines changed depending on
the position of the cadaver.
 RSTL described by Borges 1962
 Borges argued that the Langer lines represented lines of cleavage in cadavers and
not lines of relaxed tension
 relaxed skin tension lines follow furrows formed when the skin is relaxed. Unlike
wrinkles, they are not visible features of the skin. They are merely derived from
the furrows produced by pinching on the skin. These furrows are produced most
easily with pinching perpendicular to the lines. When the skin is pinched oblique to
the relaxed skin tension lines, an S-shaped pattern is created. Fewer and higher
furrows are created if skin is pinched parallel to the lines
 Left) Borges's relaxed skin tension lines in the face. (Center) Comparison of
Borges's and Langer's face lines. (Right) Comparison of Borges's and Kraissl's face
lines. Reprinted with permission from Borges, A. F. Relaxed skin tension lines
(RSTL) versus other skin lines. Plast. Reconstr. Surg. 73: 144, 1984 .
RSTL are perpendicular to muscle fibres but parallel to orientation of collagen
fibres
Lines of maximal extensibility are perpendicular to RSTL
Facial aesthetic units
Advancement flaps
 Moves directly forward into a defect without any lateral movement or rotation
 No pivot point
 The donor site is closed primarily.
 Orientation is arranged so as to benefit maximally skin elasticity and blood
supply, ie movement perpendicular to the lines of maximal tension.
 excision of Burow's triangles (excess skin at the flap base) may be necessary to
permit advancement
Pivot flaps
Types
1. Rotation flap
2. Transposition flap
3. Interpolation flap
Rotation flap
 Triangular defect
 Radius AC is extended to a point
(D) that serves as the pivot point
for the flap.
 AD should be at least twice the
length of AC
 The semicircular line CD should
be 5-8x the length of AC
 back cut or Burows triangle may
be required to gain adequate
rotation.
Interpositional flap
 rotates about a pivot point into a
defect that is nearby but not directly adjacent to the donor site, so that its pedicle
must pass over or under the intervening tissue.
 Examples are the deltopectoral (Bakamjian) flap, island flaps such as the Littler
neurovascular digital pulp flap, and subcutaneous pedicle flaps.
Transposition flap
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flap that is moved laterally into the primary defect
usually rectangular or square
critical, when designing the flap, to make it longer than the defect so that after
transposition there is sufficient length to allow closure.
2 main types
1. transposition leaving a secondary defect requiring SSG
2. transposition with direct closure of secondary defect
Tension on transposition flaps may be reduced by
1. making a wider flap
2. making a longer flap
 will increase length:width ratio and thus compromise blood supply
 dog ears

3. making an extension cut (lengthen 1 limb furthest from defect)
 shifts the pivot point
 will increase length:width ration
4. making a back cut
 shifts pivot point closer to primary defect
 will reduce the flap widtj
Examples – Z plasty, Limberg flap, bilobed, Dufourmental flap
1. Bilobed flap
 first lobe the same size as the defect and the second lobe
substantially (~50%) smaller than the first
 elevated in the submuscular plane.
 primary lobe is usually at an angle of 45° or less to the defect
 secondary lobe is usually at an angle of 90-105° to the defect
2. Limberg flap
 equilateral parallelogram with angles of 60° and 120°
 should be aligned along the line of maximum extensibility.
 XY should be aligned parallel to RSTL
3. Z plasty
 Two triangular flaps are designed so that they have in common a
central limb aligned in the direction along which additional length
is desired
 produces lengthening in one direction (along the axis of the central
limb) and shortening in another direction.
 Indications
1. Realignment of tissues/shifting of topographical structures well known for realigning structures in which a step deformity
has occurred.
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2. Release of contractures by increasing the length along the axis
of the scar and breaking up the straight-line traction of the scar.
3. Effacement of a web
Classic Z of 60 can be modified by changing size or changing
angle:
1. The larger the Z-plasty flaps, the greater the lengthening
obtained., but also more tissue laxity required for lengthening to
occur in one direction and for shortening to occur in the other
direction.
2. transposition of larger Z-plasties required seven to 10 times
more tension to effect closure than a smaller Z-plasty
3. Narrow flaps (angle , 45 degrees) are tenuous from a vascular
point of view and yields a theoretical increase in length of only
50%
4. as the angle gets larger(>75), the flaps become much more
difficult to transpose.
5. tension required to close a 90-degree Z-plasty is 10 times that
required to close a 30-degree Z-plasty.
Limitations
1. Actual length versus theoretical length – studies in vivo have
shown an increase of only 40 to 60 percent of the
mathematically predicted value.The larger the Z, the closer
actual length approximates theoretical length
2. Hazard of small Zs - If the Z-plasty flaps are too small,
insufficient lengthening of the contracted band occurs.
3. Simple Zs of the web deepens it but does not lengthen it.
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Variations
1. Z plasties in series
a. lengthening obtained in series is additive, whereas
the shortening is in parallel(a Z to give 2cm of
lengthening will cause 2 cm of shortening as
opposed to 4 0.5cm Zs which give the same
lengthening but 0.5cm of shortening
b. limitations: actual lengthening obtained is much less
than the theoretical lengthening, because the field of
tension exerted by each Z-plasty impinges on its
neighbor, in doing so limiting the overall gain in
length. Another problem with multiple Zplasties in
series is that the central flaps have a somewhat
square shape and, consequently, unlike triangles, do
not interdigitate as easily
2. Double opposing Z plasty
a. Variation of Z plasty in series but 1 is reversed.
b. advantage that the flaps remain as triangles,
interdigitating with ease.
c. Does not lead to increased length compared to
classic Z
3. 4-flap Z plasty
a. advantage of gaining length in parallel (i.e., the gain
in length of the central limb is that of two large Zplasties).
b. There are two types of four-flap Z-plasty, the 120
(2.5x) and the 90 (2x), with each angle divided in
half to create four flaps. These smaller flaps can be
more easily transposed.
4. 5-flap Z plasty
a. a double-opposing Z-plasty (a Z-plasty in series
with the addition of a V-Y plasty between the two
b. One disadvantage of the technique is that the central
flaps are somewhat square, a shape that may
c. transpose with more difficulty.
d. The theoretical lengthening obtained is 75 percent
for the double-opposing Z-plasty, plus 50 percent
for the V-Y plasty, equalling 125 percent
e. 4 flap good when there is sufficient tissue laxity to
allow its design. 5 flap good when there isn’t.
5. 6 flap Z plasty
a. similar to the 45-degree four-flap Z-plasty with an
additional limb
b. This technique recruits maximally from the adjacent
tissue; as a result, transposing the flaps is often
difficult and dog-ears occur frequently.
6. Single limb Z plasty
a. involves the transposition of a simple, triangular
flap to another area. – ie treatment of medial
ectropion
7. Dancing man procedure
a. Described for treatment of epicanthic folds
b. Similar to the double opposing Z but rectangular
flaps are created rather than triangular.
Direct Cutaneous Vessels (Axial pattern flap)
 Flaps based on vessels that run in the subcutaneous system
 Examples
i. Supraorbital, supratrochlear arteries
ii. Lateral thoracic artery
iii. SEPA, SCIA flaps
Fasciocutaneous flaps
 In 1981, Ponten rediscovered the fasciocutaneous flap (Ponten superflap). He
noticed (like Gillies before him) that by elevating a skin flap with its underlying
fascia, flap vascularity was enhanced and thus longer flaps could be raised (2.5:1
ration instead of 1:1)
 Flaps that include the fascia have 15% greater surviving length than flaps that
exclude fascia (Tolhurst, Haeseker and Zeeman, 1983 and Thomson and Kerrigan,
1987).
 Refers to flaps based not on the fact that the flap is composed of fascia and skin
but rather it is the fasciocutaneous system of vessels that is responsible for its
blood supply.
Classification (Cormack and Lamberty)
Type A:

Multiple independent perforators
Pedicle of skin and fascia incorporating branches of several usually small
fascio-cutaneous perforators arising from multiple sources and entering the
base of the flap.

To achieve maximum length and reliability, the long axis of the flap must be
parallel to the axiality of the fascial plexus.
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The flap can be proximally or distally based.

Skin can be removed to create an island flap.

 Examples:
1.
Lower leg, medially (super-flap) and laterally
2.
Upper arm based on med and lat intermuscular septa
Type B: Solitary fasciocutaneous perforator

Raised on a single fasciocutaneous perforator of moderate size which is
consistent both in presence and location.

Can be used in numerous configurations: pedicled, island, free.

Venous drainage is by subcutaneous system of veins or by venae comitantes of
the perforator.

Example
1. antecubital forearm flap
2. The saphenous artery flap
3. The scapular and parascapular flaps
Type C: Segmental septocutaneous perforators

Based on several small fasciocutaneous perforators (contained in the
fascial septum) supported by a major segmental artery and used as a free flap.

Venous drainage is usually through the subcutaneous system of veins although
veins do accompany the perforator

Examples
1. Radial forearm flap
2. Peroneal artery flap (fibula flap)
Type D: Osteo-myo-fasciocutaneous free tissue transfer

A variation of the type C flap, eg, radial forearm flap including bone.
Advantages of fasciocutaneous flaps include:
1. ease of elevation
2. quick to elevate
3. less bulk
4. high reliability
5. easier transfer than for muscle flaps and no functional impairment
6. Lamberty feels they are superior for small defects.
Disadvantages
1. Poor donor site cosmesis , must frequently be covered with a skin graft.
2. Less resistant to bacterial inoculation when compared with musculocutaneous
flaps.
3. 40% incidence of complications, increasing to 71% when used for trauma cases
(Dickson, Dickson and Roberts). 2 out of 126 flaps were lost completely.
Observe caution
1. when the patient is obese,
2. in the presence of infection,
3. where there is the possibility of trauma to the local vasculature,
4. in the presence of small vessel disease.
5. with respect to flap design

Song has coined the term septocutaneous flap that allows a distinction to be made
between those flaps where the perforators need to be dissected out
(septocutaneous) from those where the vessel need not be exposed
(fasciocutaneous).
a. Fasciocutaneous flaps thus includes type A flaps and some type B flaps.
b. Septocutaneous flaps includes some type B flaps and all type C flaps.

These flaps can be further divided according to the direction of blood flow:
a. Proximal pedicle or,
b. Distal pedicle; reverse flow; retrograde flow.
Musculocutaneous Flaps
 composites of skin, subcutaneous tissue, underlying muscle and fascia supplied by
a dominant vascular pedicle.
 essential feature of a pedicled musculocutaneous flap is that its skin territory is
supplied by perforators from the muscle, as opposed to the other possibility of a
direct cutaneous (arterial) source.
 Advantages of musculocutaneous flaps:
1.
superior closure of dead space
2.
greater resistance to bacterial infection
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3.
early increased blood flow after elevation and transfer
Mathes and Nahai classification of muscle flaps
1.
Single vascular pedicle
2.
Dominant vascular pedicle plus minor pedicles
3.
Two dominant vascular pedicles
4.
Segmental vascular pedicles
5.
One dominant vascular pedicle plus secondary segmental vascular
pedicles
muscle serves the following functions in the flap:
1.
carries the essential blood supply,
2.
provides bulk for closure of dead space,
3.
high vascularity helps control infection.
To use a minor pedicle for transfer, a delay procedure is usually required 2 weeks
before transfer
During the first year after transfer atrophy of about 25 to 50% occurs.
Muscle flaps must meet certain criteria for safe transfer
1.
the muscle must be able to transpose to the wound - the arc of rotation
must be adequate
2.
the muscle must be accessible - this usually implies superficial
location
3.
the muscle must be of adequate size (both pedicle and flap portions);
4.
the vascular pedicle must be easily located, constant and adequate;
5.
the functional loss must be minimal - the muscle must be dispensable
muscle vs myocutaneous flaps
1.
Myocutaneous flaps are better where:
i. aesthetic skin match
ii. substantial soft tissue is required (as in breast reconstruction)
2.
In the lower leg, myocutaneous flaps may be larger than the equivalent
muscle flap.
3.
Muscle flaps leave much better donor sites (simple incision) than
myocutaneous flaps (grafted donor site).
4.
Muscle flap + SSG at first would not appear to give as good a coverage
as a myo-cutaneous flap with its full thickness skin and subcutaneous
fat. This has proved to be untrue. Muscle + SSG are of proven
durability.
Perforator Flaps
 Original description - a perforator flap were defined as a free flap consisting of
skin and subcutaneous fat only, based on a transmuscular perforator vessel that
was dissected by splitting the muscle and not harvesting it. (Koshima 1989)
 Thus an evolution of a myocutaneous flap
 Gent consensus (PRS Oct 2003) on perforator flap
o A perforator - any vessel that enters the superficial plane through a
defined fenestration in the deep fascia, regardless of origin.
o 2 types of perforators (direct or indirect)
o Definitions
1. A perforator flap is a flap consisting of skin and/or subcutaneous fat.
The vessels that supply blood to the flap are isolated perforator(s).
2.
3.
4.
5.
6.
These perforators may pass either through or in between the deep
tissues (mostly muscle).
A muscle perforator is a blood vessel that traverses through muscle to
supply the overlying skin.
A septal perforator is a blood vessel that traverses only through septum
to supply the overlying skin.
A flap that is vascularized by a muscle perforator is called a muscle
perforator flap.
A flap vascularized by a septal perforator is called a septal perforator
flap.
A perforator flap should be named after the nutrient artery or vessels
and not after the underlying muscle. If there is a potential to harvest
multiple perforator flaps from one vessel, the name of each flap should
be based on its anatomical region or muscle.
different types of direct and indirect perforator vessels with regard to their surgical
importance. 1, Direct perforators perforate the deep fascia only; 2, indirect muscle
perforators predominantly supply the subcutaneous tissues; 3, indirect muscle perforators
predominantly supply the muscle but have secondary branches to the subcutaneous
tissues; 4, indirect perimysial perforators travel within the perimysium between muscle
fibers before piercing the deep fascia; 5, indirect septal perforators travel through the
intermuscular septum before piercing the deep fascia.
 Advantages of perforator flaps over traditional musculocutaneous flaps include:
1) less donor site morbidity;
2) muscle sparing;
3) versatility in design to include as little or as much tissue as required;
4) improved postoperative recovery of the patient.
 Disadvanatges
1) Increased complexity
2) variability in the position and size of the perforator vessels.
3) small perforator vessels have the tendency to stretch, kink, or twist,
Examples
1) DIEP
2) SGAP
3) IGAP
4) Thoracodorsal
5) Anterolateral thigh flap
6) Transverse branch of LCFA (to TFL)
7) Medial sural artery