DEPARTMENT OF PLASTIC AND RECONSTRUCTIVE SURGERY SKIMS SRINAGAR

1. Department of Plastic And
Reconstructive Surgery
Sher i Kashmir Institute of
Medical Sciences Srinagar
Seminar Topic: Properties of Skin and
Skin Expansion

2. Properties of Skin and
Skin Expansion
Presentor : Dr Junaid khiurshid
Moderator : Dr Umar Farooq

3. Structure
1- Epidermis
• - Stratum Corneum
• - Viable Epidermis
• 2- Dermis
• 3- Hypodermis

5. Definitions
• Tension: taut - tense - stretched firmly not slack -
resists deforming forces.
• Elasticity: recoils or springs back to its original
length or shape after being stretched or squeezed.
• Resilience: springy- adaptive – readily recovering
from shock.
• Tensile Strength: the degree to which it can be
elongated before it tears.

6. Mechanical Skin Properties
• Cytoskeleton Supports the cell and gives it its
shape
• Glycosaminoglycans( GAGs) & Proteoglycans
Viscoelastic properties & resistance to
compression
• Collagen fibers Tensile strength (resistance to
breaking or tearing)
• Elastic fibers Tension, resilience, elasticity

7. Physics

8. Viscoelasticity
• Viscoelasticity is the property of materials that
exhibit both viscous and elastic characteristics
when undergoing deformation.

9. Contd.
• The viscosity of a viscoelastic substance gives the
substance a strain rate dependence on time.
characteristics when undergoing deformation.
• Unlike purely elastic substances, a viscoelastic
substance has an elastic component and a viscous
component.

10. Stress relaxation
• Stress relaxation is a property of biological tissues
that is related to their viscoelastic properties
• The decline in pressure (stress) over time at a
constant volume (strain) is termed "stress
relaxation."

11. Contd.
• Isometric.
• Bladder is mostly smooth muscle, shows a high
degree of stress relaxation while a tendon that is
primarily composed of collagen shows virtually no
stress relaxation

13. Creep (deformation)
Creep (sometimes called cold flow) is the
tendency of a solid material to move slowly or
deform permanently under the influence of
persistent mechanical stresses
Creep is a time-dependent permanent
deformation of a solid material at a stress
level lower than the yield strength of the
material and subjected to an elevated
temperature.

14. Contd.
Mechanical creep defined as the elongation of skin
with a constant load over time beyond intrinsic
extensibility.
Biological creep defined as expansion due to
increased mitotic activity leading to true gain of
tissue

16. HISTORY OF TISSUE EXPANSION
• Neumann induced soft tissue growth with a
subcutaneously implanted balloon in an attempt to
reconstruct an external ear deformity.
• Radovan and Austad simultaneously evolved the
concept of purposeful soft tissue expansion with
use of an implanted silicone balloon.

17. • Radovan's device contained a self-sealing valve
through which saline was periodically injected to
increase size of the prosthesis.
• Austad's prosthesis was devised as a self-inflating
device using osmotic gradients driven by salt placed
within the expander.

18. BASIC PRINCIPLES
• Tissue expansion is a protracted procedure that
may involve temporary, but very obvious, cosmetic
deformity.
• Emotionally stable patients of all ages tolerate
tissue expansion well. Noncompliant or mentally
impaired patients are poor candidates.
• Smokers have a higher risk of complications.

19. Contd.
• Tissue expansion is generally best performed as a
secondary reconstructive procedure rather than in
the acute trauma period.
• Expansion can be performed adjacent to an area of
an open wound before definitive closure, but such a
procedure carries the risks of infection, extrusion,
and less than-optimal results.
• Tissue expansion is best suited to those patients
who require definitive, optimal coverage ,when
time is not of the essence.

20. Incision planning and implant
selection
• The proposed type of flap
• – advancement
• - rotation
• - Interpolation
• The simpler the flap, the less the potential for
complication.

21. Planning
• Incisions are incorporated into tissue that will
become one margin of the flap
• Aesthetic units are reconstructed
• Scars should be in minimally conspicuous locations
• Tension on suture lines should be low

22. Contd.
• Incisions should be planned to minimize tension on the
suture line and risk of extrusion.
• Tension from the initial inflation on the suture line will
be greater when incisions are parallel to the direction
of expansion than when they are perpendicular to it.
• Undermining of the prosthesis should be sufficient
enough that the prosthesis can be easily
accommodated and the wound can be closed in
multiple layers.
• The inflation valve and tubing should be maintained at
a site away from the incision.

23. The size of the implant
• The size of the implant selected should closely
relate to the size and shape of the donor surface.
• An implant equal to or slightly smaller than the
donor area is selected.
• In general, the use of multiple small expanders is
better than the use of one large expander. Inflation
of multiple prostheses proceeds more rapidly and
complications are fewer.
• Multiple expanders also allow the surgeon to vary
the plan for reconstruction after expansion

24. Implant and distal port positioning
• If a remote filling port and reservoir is chosen, it
must be placed superficially in subcutaneous tissue,
where even an extremely small port is easily
palpable under stable skin.
• To minimize discomfort, it is occasionally possible to
position a filling port in an area that is relatively less
sensitive.
• The port should be placed in a location that will not
be subjected to pressure. Bony prominences are
avoided

25. Implant inflation strategy and
technique
• Implants should be partially inflated immediately
after wound closure. This allows closure of “dead
space” to minimize seroma and hematoma
formation.
• It also smoothes out the implant wall to minimize
risk of fold extrusion.
• Enough saline is placed to fill the entire dissection
space without placing undue tension on the suture
line.
• Serial inflation usually starts 1–2 weeks after initial
placement.

26. Contd.
• Inflation reservoirs seal best when a 23-gauge or
smaller needle is used. A 23-gauge butterfly
intravenous needle is especially useful.
• Frequent small-volume inflations are better
tolerated and are physiologically more suited to the
development of adequate overlying tissue than are
large infrequent Inflations.
• Inflations proceed until the patient experiences
discomfort or blanching of the overlying skin

27. Contd.
• Devices such as pressure transducers and oxygen
tension monitors are available to help determine
proper inflation.
• An objective inspection of the patient’s response is
usually a reliable indicator of appropriate inflation.
• Serial inflations proceed until an adequate amount
of soft tissue has been generated to accomplish the
specific surgical goal.

28. Contraindications
• Active infection anywhere in the body.
• Clinically persistent or recurrent cancer.
• Poor vascularization of tissue in the area
where the implant is to be used
• History of compromised wound healing.
• Compromised immune system.
• History of sensitivity to foreign materials

29. Biology of tissue expansion
Children of Fire (Africa)

30. Epidermis
• Early after placement of the prosthesis, significant
thickening of the epidermis is evident. Within 4 to 6
weeks, epidermal thickness generally returns to
initial levels, but some increase in thickness persists
for many months.
• Hair follicles and accessory skin structures are
compressed but no evidence of degeneration.

31. Contd.
• Animal studies demonstrate that there may be an
increase in number of hairs and density
proportional with expansion.
• Melanocytic activity is increased during expansion
but returns to normal within several months after
completion of reconstruction

32. Right with expander

33. Dermis
• The dermis decreases rapidly in thickness over the
entire implant during expansion.
• Dermal thinning persists at least 36 weeks after
expansion is completed . A dense fibrous capsule is
formed around the implant, which becomes less
cellular over time.
• • The capsule is thickest at 2 months of expansion.
Progressive collagenization with well-organized
bundles develops during 3 months.

34. Contd.
• Expanded tissue demonstrates a quantitative
increase in collagen content of the dermis. After
expansion, the relative proportions of type I and
type III collagen are not significantly changed in the
dermalepidermal or subcutaneous-capsular
interface.
• Mitotic activity in the capsule fibroblast is maximum
about 96 hours after expansion.
• The application of a constant pressure beyond 96
hours results in progressive decrease in mitotic
activity

35. Muscle
• Muscle atrophies significantly during the process of
expansion, whether the prosthesis is placed above
or below a specific muscle .
• The effects on human muscle after expansion have
demonstrated occasional histologic ulceration.

36. Contd.
• Focal muscle fiber degeneration with glycogen
deposits and mild interstitial fibrosis have been
noted. Some muscle fibers show disorganization of
the myofibrils in the sarcomeres.
• Expansion of skeletal muscle is not a stretching
process but rather a growth of the muscle cell
accompanied by an increase in the number of
sarcomeres per fiber.

37. Bones
• There is a decrease in bone thickness and volume in
cranial bone beneath the expander, but bone
density is unaffected.
• An increase in bone volume and thickness occurs
predominantly at the periphery of the expander.

38. Contd.
• Osteoplastic bone resorption occurs beneath
expanders, and a periosteal inflammatory reaction
is seen at the periphery of the expander.
• Cranial bone appears to be significantly more
affected than long bone is. Long bone remodeling
begins within 5 days after removal of the expander,
and the long bone is completely normal within 2
months.

39. Vascularity of Expanded Tissue
• It has been clinically and histologically demonstrated
that a large number of new vessels are formed adjacent
to the capsule.
• The content of collagen fibers in existing vessels initially
decreases after expansion.
• Elastic fibers in existing blood vessels initially increase,
probably as a response to mechanical stress.
• Angiogenesis probably occurs secondary to ischemia of
the expanded tissues.
• Cells expressing vascular growth factor is significantly
increase

40. SURVIVAL
• Flaps elevated in expanded tissue have
significantly greater survival rates compared with
acutely raised and delayed flaps

41. Ultrastructure of Expanded Tissue
• The epidermis demonstrates a reduction of intercellular
distance and a significant decrease in the undulation of
the basal lamina .
• The dermis displays large, compact bundles of collagen
fibers oriented in parallel fashion over the implant
surface.
• Active fibroblasts are found in the expanded dermis.
• Myofibroblasts develop in the deep dermis adjacent to
the capsule.
• Skeletal muscle demonstrates pressure atrophy with
increased mitochondria and abnormal rearrangement
of sarcomeres

42. Molecular Basis for Tissue Expansion
• Intracellular tension and cell structure are
maintained by a system of microfilaments within
the cytoplasm.
• These microfilaments act to transduce signals to
adjacent cells and play a critical role in initiating
transduction cascades within the cell.
• Protein kinase C plays a pivotal role in signal
transduction.
• Mechanical strain on cell walls activates inositol
phosphatase, phospholipase A2, phospholipase D,
and other messengers

45. • Activation of these components results in protein
kinase C activation. Protein kinase C is associated
with nuclear proteins, intracellular signals can be
transmitted to the nucleus.
• Many growth factors, including platelet-derived
growth factor and angiotensin II, play a role in strain
induced cell growth.
• Platelet-derived growth factor has a effect of
stimulating cutaneous cell proliferation.
• Transforming growth factor-β production has also
been demonstrated in stretch in vitro models and
has been implicated in extracellular matrix
products.

46. The Source of Increased Tissue from
Expansion
• The increase in skin surface area over the expander
includes normal skin brought in from adjacent areas
as well as new skin generated by increased mitosis.
• • Increased mitotic activity in the epidermis directly
overlying the expansion. Serial inflations of the
prosthesis result in serial increases in tritiated
thymidine uptake.
• • With deflation of the implant, a significant
decrease in the rate of the epidermal mitosis below
normal baseline occurs.

47. Radovan's expander
• Radovan's expander consisted of a silicone prosthesis
with two valves, each connected to the main reservoir
by silicone tubing.
• One valve was used for injection; the other was used as
a means to withdraw fluid. Technologic improvements
resulted in a single valve for both purposes.
• The filling reservoir may be incorporated directly into
the prosthesis. Such devices have the advantage of
avoiding the remote port.
• The valve in the integrated prosthesis can be difficult to
palpate.
• Breast reconstruction with these prostheses has
become popular..

49. Expanders with distal ports
• Remote filling ports.
• Advantage of minimizing the risk of implant puncture
during inflation.
• The distal , self-sealing injection port and inflation
reservoir are connected to the prosthesis by alength of
tubing.
• This allows the injection port to be placed away from
the expander pocket.
• It is also possible to move the inflation port of a distant
reservoir to the exterior of the body; this location
facilitates inflation, particularly when the expansion is
accomplished by family member.

50. DISTAL PORT

51. Expanders with integrated ports
• The inflation reservoir may be incorporated directly in
the prosthesis.
• Advantage of avoiding the remote port and its
associated mechanical problems.
• Risk of inadvertent perforation of the prosthesis during
inflation is higher .
• Magnetic and ultrasonic devices can be useful when the
valve is difficult to locate and metal finding devices
have been designed.
• Expander prostheses with integrated valves are
particularly popular for breast reconstruction where
adequate soft tissue and p

53. Self-inflating expanders
• Self-inflating expanders have become available
largely through Europe.
• These contain osmotic hydrocolloids that cause
migration of extracellular water through the silicone
membrane of the device.
• The first such expander was devised by Dr. Austad
and was used experimentally.
• It was not approved by the Food and Drug
Administration

54. Tissue expansion in
special cases

55. Burns
• Reconstruction should be carried out after all burns
have and scars have matured.
• Planning is particularly important in these cases so
that a minimum number of suture lines is produced
and that these suture lines do not cross aesthetic
units.
• Significant late distortion and contracture may
result in excessive scars placed in burned tissue,
particularly in the facial area

57. Tissue expansion in children
• Skin and soft tissue are always thinner in children
than in adults. These tissues are probably better
vascularized but less resistant to trauma.
• Tissue expansion has a higher complication rate in
children than in adults.
• Major complication risk – particularly extrusion – is
more common at the second, third, and fourth
serial expansion. This is particularly true in the head
and neck (with the exception of the scalp).
• Small-volume inflation at frequent intervals is
especially useful in children because

58. Expansion of myocutaneous, fascial,
and free flaps
• Myocutaneous flaps are the standard of care for the
treatment of large defects, particularly when bone
and vital structures are involved.
• The territories of standard flaps are well described.
These territories can be considerably enlarged by
placing an expander beneath the standard
myocutaneous flap, and an extremely large flap can
be developed over a short period.

59. Contd.
• Expansion increases the vascularity of the flap and
allows a large, adjacent random area to be carried
with the original flap.
• Myocutaneous flaps such as the latissimus dorsi
and pectoralis can be expanded to almost double
their surface area, allowing coverage of almost any
defect on the abdomen or thorax.
• Expanders of up to 1000 Ml can be placed beneath
such flaps and rapidly expanded

60. Expanded full-thickness skin grafts
Donor defect is usually created by harvesting full-thickness
grafts.
• The placement of a large tissue expander beneath the donor
site can result in a large full-thickness graft that is
particularly useful in resurfacing large areas .
• The best color matches are generated when the full
thickness graft is expanded and harvested as close as
possible to the recipient site.
• The periorbital area and the area around the mouth are
particularly well suited to reconstruction with expanded full-
thickness grafts harvested from the supraclavicular area.
• Expanded full-thickness grafts are very helpful in
reconstructing defects of the forehead . A single full-
thickness graft can be harvested from the supraclavicular
• area or from under the breast fold.

61. Contd.
• The full-thickness graft is approximately 10–15%
larger than the recipient area.
• Expanded full-thickness skin grafts require more
immobilization than split thickness.
• A bolster dressing or, ideally, a VAC sponge dressing
is required. The graft is sutured in place and a VAC
sponge placed over the graft; 125 mmHg of
negative pressure is maintained for 4 days.

62. APPLICATION OF TISSUE
EXPANSION

63. HEAD AND NECK
• The skin of the face can be subdivided into five tissue specific
areas:
• 1. The scalp
• 2. The forehead is a continuation of the scalp, but it is
distinguished from the scalp by its thick skin, large number of
sebaceous glands, and lack of hair.
• 3. The nose is embryologically related to the forehead, so it
closely mimics the forehead in color, texture, and sebaceous
gland content.
• 4. The lateral cheek areas, neck, and upper lip have fewer
sebaceous glands; the skin is thinner, and the hair-bearing
pattern is significantly different in quality and quantity from that
on theremainder of the body.
• 5. The skin of the periorbital areas is extremely thin and pliable,
containing a minimal number of sebaceous glands

64. Scalp
• Tissue expansion is the ideal procedure for the
reconstruction of scalp defects.
• Expansion of the scalp is well tolerated and is the
only procedure that allows development of normal
hair-bearing tissue to cover the areas of alopecia.
• The amount of scar and deformity generated is
considerably less than other procedures such as
serial reduction and complex multiflap procedures

68. Nose
• The forehead is anatomically and histologically
identical to the scalp except for its different
numbers of sebaceous glands and hair-bearing
follicles.
• Reduction or increase of the surface area of the
forehead by 20–25% is not usually readily apparent
after appropriate hair styling

69. Contd.
• By expanding the scalp in conjunction with
expanding the forehead, better symmetric brow
positioning is achieved while maintaining the normal
hairline.
• Expansion of the forehead is useful in many
craniofacial anomalies with low hairlines.
• Expansion of the remaining forehead is
accomplished and moved into a cephalad direction.
• The intervening hair-bearing scalp is excised

70. Lateral face and neck
• The type of skin on the lateral facial areas and neck
is essentially the same.
• A large Mustardé expanded rotation flap can be
developed on the neck for use in facial
reconstruction.
• In children, there is a higher risk of extrusion
problems in the expansion of this area of the face .
• Adults, such reconstruction can be accomplished
with relative ease. The flap is based inferiorly and
medially

72. Giant hairy nevus face

76. Nose
• Reconstruction of major defects of the nose, including
total nose reconstruction, may be facilitated by pre
expanding the forehead skin.
• when total nose reconstruction is performed,
expansion of the entire forehead with a 400–600-mL
prosthesis generates an adequate number of large, well
vascularized flaps to accomplish both total nose
reconstruction and closure of the donor site.
• Because the color and texture of the forehead are
ideally suited to reconstruction of the nose, this
procedure makes reconstruction of any nasal defect
possible.

77. • A cranial bone or rib graft is taken to reconstruct
the dorsum of the nose. This is either secured to
the remaining nasal bone or attached by a plate to
the skull.
• The nasal cartilage is reconstructed bilaterally with
cartilage from the conchal bowl.

78. Mucosal melanoma nose

79. Ear
• Most cases of microtia and traumatic ear
deformities can be reconstructed without
expansion.
• Expansion is helpful when skin and soft tissue are
insufficient for reconstruction.
• As with all ear reconstructions, a child should be
approximately 7 years of age before reconstruction
is begun.

81. Periorbital area with expanded
full-thickness grafts
• The periorbital area contains skin that is soft and
pliable.
• Little tissue in the periorbital area can be expanded
or move easily.
• When large areas require reconstruction, full
thickness skin grafts from expanded donor sites are
recommended.
• Replacement of aesthetic units – the entire
periorbital area or the upper or lower lid – gives the
best result .

82. Reconstruction in the breast, chest,
trunk, and extremities.
• Tissue expansion was introduced by Chemar
Radovan in 1982 to facilitate breast reconstruction
in post mastectomy patients because these patients
were found to have insufficient chest wall tissue for
placement of the implant.

83. The Hypoplastic Breast
• Tissue expansion has played an important role in
the reconstruction of both acquired and congenital
breast hypoplasia.
• Management of the deformity depends on the
degree of breast asymmetry, the nature of the
deformity, the quality of the chest wall soft tissue,
and the age of the patient at presentation

87. The immature breast
• Management of young adolescents presenting
with breast Asymmetry. Adolescence is a
critical time that is characterized by intense
social pressures and self awareness of a
developing physique, so failure to address the
problem of breast asymmetry can result in
psychological problems. These patients do not
need full maturity for reconstruction

88. Correction of Poland syndrome
• Poland syndrome involves
- abnormal development of the breast
- thoracic wall deformities
- deformities of the upper extremity
- vertebral anomalies.
• Poland syndrome exhibits a uniform absence of the
sternal head of the pectoralis major muscle.
• Abnormalities in the anterior ribs and costal cartilages
and deficiencies of the muscles of the scapular area,
including the latissimus dorsi.
• Other findings include deficiency of subcutaneous
tissue; hypoplasia, aplasia, or malposition of the
nipple–areola complex; and deficiency of breast tissue

89. Expansion of the trunk
• The trunk and abdomen are well suited to tissue
expansion in individuals of all ages.
• Because of the large adjoining surface area from which
tissue can be recruited, large prostheses can be placed
and flaps quickly expanded.
• Large deformities, such as burns, giant hairy nevi, and
other congenital anomalies, the expanders are inflated
maximally and the flaps are advanced. The prostheses
are left in place and reexpansion is carried out in the
subsequent weeks.
• In the abdomen, two or three serial expansions are
usually well tolerated.

90. Ruptured omphalocele with liver covered in alloderem then
VAC applied FB STSG

91. At 4 years expanders placed beneath and lateral to rectus
muscles to generate adequate muscle and skin for
abdominal closure

92. Expansion in the extremities
• Skin and soft tissues of the extremities tolerate
tissue expansion well.
• The capsule that develops adjacent to the expander
has a resilient surface that can be transposed over
joints and tendons to decrease adhesions.

94. IMPLANT FAILURE
• Despite design improvements, the use of an
excessively large needle or the inadvertent
puncture of the implant can lead to implant
deflation.
• To maximize sealing of the valve, the implant
reservoir should be entered at a 90° angle.
• • If there is any question about the location of the
inflation reservoir, radiologic or sonographic
techniques may be helpful

95. INFECTION
• The introduction of bacteria to the wound in the
perioperative period is the most common cause of
early infection.
• Areas susceptible to lymphedema, such as traumatized
lower extremities, carry a significantly higher rate of
infection.
• An area of copious lymphatic drainage, such as the
neck or the groin, also tends to accumulate lymphatic
fluid around a prosthesis and is more susceptible to
infection.
• If infection occurs late in the course of expansion, the
prosthesis can be removed and the expanded tissue
advanced after irrigation of the infected cavity.

96. IMPLANT EXPOSURE
• Implant exposure can occur both early in the postoperative
period and after a protracted course ofexpansion.
• Treatment of the exposed implant depends on the timing of
exposure.
• Exposure early after placement is usually related to
inadequate dissection or use of an excessively large
prosthesis that abuts on wound closure.
• If the prosthesis becomes exposed soon after placement, it is
best to remove it and reoperate 3–4 months later.
• Late exposure is usually related to excessively rapid or
overzealous inflation.
• If minimal or late exposure occurs during the course of
expansion, the procedure can continue withthe use of
antibiotic creams on the exposed area: In this situation,
multiple, rapid fillings are done to generate adequate tissue.

97. COMPROMISE AND LOSS OF FLAP
TISSUE
• To ensure vascularity ,one should attempt to
maintain a major axial vessel in the expanded
tissue.

98. Special Scenario
• Erin and Abbey Delaney were born in Philadelphia
on July 24, 2016. As many twins are, they were
close—specifically, they were joined at the top of
the head.

99. Erin And Abby

100. • “We are very thankful to be able to look forward to
going home with two separate, healthy girls,” said
the twins’ parents, Abdelmajeed and Enas Gaboura,
in a statement.