Download Abdominal Wall Reconstruction

Abdominal Wall Reconstruction
Introduction
Abdominal wall defects may be skin, subcutaneous, myofascial or combination of the
above
Aetiology of common defects
Tumours
Desmoid
 Often found in the anterior abdominal wall and is an accumulation of fibrous tissue
arising from the musculoaponeurotic layer of the torso
 F>M
 3rd -5th decades and usually after pregnancy
 Histological benign but can be locally invasive
 40% recurrence within 2 yrs
 Radiation may reduce recurrence when adequate margins can not be obtained
Dermato fibrosarcoma protruerans
 Rare cutaneous tumour that presents as a slow growing blue red nodule commonly
on the trunk
 The tumor extensively infiltrated the dermis and the subcut tissue
 Aggressive resection with wide margins
Primary and secondary malignancies
 Sarcomas are amongst the most common primary malignancy of the abdo wall
 Wide excision and rads
 Often full thickness excision
Infection
Necrotising fasciitis
Trauma
 Traumatic abdominal wounds are usually from GSW
 usually full thickness and result in intrabdo injury thus in contaminated wounds
Incisional Hernia
 incidence of ventral hernia after midline laparotomy ranges from 2% to 11%
 Post op wound infection and dehiscence increases herniation rates
 Other predisposing factors
1) age
2) type of incision
3) obesity
4) malnutrition
5) steroid
6) anaemia
Abdominal compartment syndrome
 Treatment involves opening the abdominal cavity and managing the primary
etiology until the abdomen can be closed again
 open management is performed until the abdomen can be safely closed.
 there exists a population in whom the abdomen cannot be safely closed. In these
patients, closure is usually obtained by placement of absorbable mesh and
subsequent skin grafting, which leaves the patient with a large ventral hernia and a
potential skin deficit that will need to be managed.
Anatomy
Skin and subcutaneous tissue
 anatomy of the abdominal skin envelope of an individual is related to body
habitus and previous surgery.
 The obese patient has an excess amount of skin.
 Patients with previous incisions may have significant disturbances in the
cutaneous blood supply. Tissue expansion will change the anatomy of the dermis
and epidermis, and the capsule will assist in skin perfusion
 The underlying subcutaneous tissue is divided into the superficial and deep layers,
which are separated by Scarpa’s fascia.
 Whereas the superficial layer covers the entire abdominal wall, the deep layer is
limited to the lower abdomen, below the level of the umbilicus.
Musculofascial layer
 Fusion of the abdominal fascia forms three lines - the linea alba and the two linea
semilunaris
 The deep fascia is composed of aponeurosis of the EO, IO and TA which fuse at
the lateral wall of the RA to form the semilunar lines
 Above the arcuate line, the aponeurosis of the EO and IO form the Ant Fascial
layer and the aponeurosis of the IO splits to join the TA fascia to form the post
layer
 Below the arcuate line all three layers join together to form the ant layer of the
rectus sheath
 Muscular layer divided into
1. Anterior layer – rectus abdomimus and pyramidalis
2. Anterolateral layer – EO, IO TA
3. Posterior layer – quadratus lumborum
Vascular supply
 Three zones (Huger)
1. Zone I
a. area between the lat border of the rectus sheath and extending to the costal
margin and xiphoid down to a line drawn between the ASIS
b. The blood supply to this zone is from the DIEA and DSEA perforators
2. Zone II
a. covers a line drawn below the ASIS and extends to the inguinal creases
b. SIEA, SEPA, circumflex iliac
3. Zone III
a. flanks and lateral abdomen,lateral to zone I and sup to Zone II
b. supplied by the intercostal, subcostal, and lumbar arteries
c. travel circumferentially on the transversus abdominis, perforating the
oblique muscles and supplying the overlying skin.
Ian Taylor PRS Jan 1984
 The vascular territories of the superior and the deep inferior epigastric arteries
were investigated by dye injection, dissection, and barium radiographic studies. By
these means it was established that the deep inferior epigastric artery was more
significant than the superior epigastric artery in supplying the skin of the anterior
abdominal wall.
 Segmental branches of the deep epigastric system pass upward and outward into
the neurovascular plane of the lateral abdominal wall, where they anastomose
with the terminal branches of the lower six intercostal arteries and the
ascending branch of the deep circumflex iliac artery.
 The anastomoses consist of multiple narrow "choke" vessels. Similar connections
are seen between the superior and the deep inferior epigastric arteries within the
rectus abdominis muscle well above the level of the umbilicus.
 Many perforating arteries emerge through the anterior rectus sheath, but the
highest concentration of major perforators is in the paraumbilical area. These
vessels are terminal branches of the deep inferior epigastric artery. They feed into a
subcutaneous vascular network that radiates from the umbilicus like the spokes of
a wheel. Once again, choke connections exist with adjacent territories: inferiorly
with the superficial inferior epigastric artery, inferolaterally with the superficial
circumflex iliac artery, and superiorly with the superficial superior epigastric
artery.
Lymphatics
 Below the umbilicus, in zone II, the drainage is to the inguinal nodes. Deeper
drainage occurs by means of the deep epigastric vessels to the external iliac nodes.
 Zone I drains both to the deep epigastrics and follows zone III drainage to the
lateral lumbar nodes and superficial inguinal nodes.
Innervation
 Intercostal, subcostal, iliohypogastric and ilioinguinal supply motor and sensory
innervation and arise from the nerve roots T7-L4
 rectus abdominis muscle is innervated by the five lower intercostal nerves as well
as the subcostal nerve.
 external oblique is innervated by the intercostal, subcostal, and iliohypogastric
nerves.
 internal oblique and transversus abdominis muscles are supplied by the intercostal,
subcostal, iliohypogastric, and the ilioinguinal nerves.
Reconstruction
Goals of abdominal reconstruction are
1) restoration of function and integrity of the musculofascial abdominal wall
2) prevention of visceral eventration
3) provision of dynamic muscular support
Pre op assessment
History
Medical
1. Pulmonary status – increased risk of post op cx
2. Nutritional status – affects wound tensile strength
3. Immunosuppression - affects wound healing
Examination
1) Assess components that are lost and need reconstruction
1) skin
2) soft tissue
3) fascia
2) Assess wound bed
 Assess if tissue loss is relative or absolute – relative is seen when the soft
tissue contracts and the bowel distends –easier to repair than if absolute
loss of tissue
 Inflammation and edema affect the ability to advance tissue and if possible
delay reconstruction until inflammation improves
 The infection rate for a clean wound is 1.5 to 3.0 percent, for a clean
contaminated wound 3 to 4 percent, for a contaminated wound 8.5 percent,
and for a dirty wound as high as 40 percent.
 Presence of radiation changes
 Previous mesh and incisions
 Presence of enterocutaneous fistulas
Investigations
CT scan may be beneficial in assessing size of ventral hernia and position of muscle
Immediate vs delayed reconstruction
 Immediate is preferred
 Procedure delayed if
1) unstable patient
2) reconstruction option limited or risky
3) wound contaminated
4) further procedure is planned
 if definitive reconstruction needs to be delayed, use VAC dressing + SSG to
temporalise the wound.
 If abdominal reconstruction is delayed, surgery should be avoided for 6 months or
until the previous abdominal scar has fully matured. This will decrease the number
of adhesions and the density of the scar tissue.
Defect Classification
 According to component loss
1. Partial or Complete
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2. Skin, musculofascial or both
Sub classified according to location and size
Hurwitz defined topographic locations to aid in approach to the reconstruction
Midline defects
 more difficult to reconstruct due to limited arc of rotation for local flaps
and regional flaps are usually harvested from the lateral position and thus
are difficult to advance to the midline.
 In midline defects with relative tissue deficiency, tissue can be advanced
with fascial relaxation incisions(component separation) or staged pleating
of mesh.
Lateral defects
 component separation is of limited use and achievable myofascial
advancement will decrease by only one half in this setting
 Most local and distant flaps may be rotated easily into lateral defects
Defects with a poor vascular bed secondary to radiation, regardless of size, are best
managed with cutaneous and fasciocutaneous flaps originating outside of the
radiation field
For defects greater than 15 cm in size, options include local random flaps, axial
skin flaps, and pedicled fasciocutaneous flaps, all of which can be enlarged with
tissue expansion.
Reconstruction Algorithm
Methods of closure
Skin grafts
 used if the adequate soft tissue is well perfused and there is adequate support for
the abdomen
 SSG can be placed directly onto the abdominal viscera but they are frequently
unstable and promote adhesions and lack of structural integrity – often require use
of abdominal binders
 If further revisions planned - takes least 6 months for mesh to implant and the skin
graft to separate from the abdominal viscera
Composite reconstruction
Direct closure
 Best suited for wounds <6cm
Component Separation (Ramirez PRS 1990)
 uses bilateral, innervated, bipedicle, rectus abdominis- transversus abdominisinternal oblique muscle flap complexes transposed medially to reconstruct the
central abdominal wall.
 Best for midline defects
Method
 procedure is begun by elevating the skin flaps off of the underlying abdominal
musculature in a lateral direction toward the anterior axillary line
 A vertically oriented incision parallel with the linea semilunaris is made 1 cm
lateral to it to identify and develop the plane beneath the external oblique fascia but
superficial to the internal oblique fascia
 careful not to dissect deep to this layer to avoid injuring the internal oblique fascia
or muscle.
 Deep dissection here may damage the segmental innervation of the rectus
abdominis muscle or injure the Spigelian fascia, thus predisposing the patient to a
Spigelian hernia.
o NB: Spigelian hernia is an acquired ventral hernia through the linea
semilunaris. Nearly always found above the level of the inferior
epigastric vessels, and most often occur where the semicircular line fold of Douglas - cross the linea semilunaris.
 dissection proceeds in this relatively avascular intermuscular plane and is
continued in a lateral direction beyond the area of skin undermining to at least the
level of the midaxillary line
 If additional mobility of these structures on either side of the midline is desired,
then the dissection in the intermuscular plane can be continued to the posterior
axillary line.
 In the rare instance that additional advancement is needed, the rectus muscle can
be elevated off of the posterior rectus sheath in its entirety. Two centimeters of
additional advancement can be obtained at each level by using this maneuver
 A total of 12cm, 20cm and 10cm of advancement can be obtained in the upper ,
middle and lower thirds respectively
 leave the anterior rectus fascia intact to allow secure suture placement.
 recurrence rates between 0% and 11% reported in the literature
 A useful modification is an incision of the posterior rectus sheath, which is then
dissected off the rectus muscle to allow additional medial mobilization.
Tissue expansion
 used to close skin and subcutaneous defects greater than 15 cm in size after
temporary control is achieved with a skin graft
 Expanders are inserted between internal oblique and transversus abdominis
(Hobar) or between EO and IO (Jacobsen)
 Skin stretch is best over ribs, ilium, or lumbar fascia.
 Advatanges – reconstruction can be performed with well vascularized, innervated,
autologous tissue.
 Disadvantages
1. lengthy, multistaged procedures
2. high complications rate – 20-30%
 Others have used inflation of air directly into the peritoneal cavity over days as a
method of tissue expansion
Reconstruction of Abdominal Support
Direct Closure
 Partial myofascial defects smaller than 3 cm in size are closed primarily.
Alloplasts
 Classified as
o meshed vs unmeshed
o absorbable vs non absorbable
 Use of prosthetics in defect closure requires the presence of adequate skin and
subcutaneous coverage as well as an adequate wound bed
 Non- meshed products prevent bacterial egress and inhibit collagen formation
 Meshed materials allow septic drainage, provide easy access to the abdominal
cavity and allow granulation tissue to grow within the interstices for added strength
 Attempts should be made to protect the intraabdominal contents with omentum –
others have brought omentum out and placed it above the mesh (risk is hernia
along the exit site)
 Failure of prosthetic material occurs with excessive wound tension, poor wound
status, and a history of infection.
 complications including seroma formation, infection, fistula, and repair failure
 Types:
1. polypropylene mesh (Marlex)
a. As a result of its macroporous structure, this permanent mesh induces
intense fibrovascular infiltration and is incorporated into the surrounding
musculofascial tissue edges of the defect.
b. Unfortunately, the same host response can cause dense adhesions when
the mesh is placed directly over the bowel and other visceral organs.
c. Resistant to infection will initially take a graft but eventual mesh
extrusion will occur in majority
d. Best used under a flap
e. Of the two types of polypropylene mesh, Prolene mesh has lower
complications rates than does Marlex mesh
f. Caution with intraabdominal placement with risk of enterocutaneous
fistula – ensure inlay mesh is under tension and wrinkle free.
g. composite mesh devices composed of a structural polypropylene mesh
and an anti-adhesive component have been shown to cause fewer bowel
adhesions than polypropylene mesh
2. Gortex
a. Incorporates poorly with soft tissues - produces fewer adhesions and
more easily removed - associated with decreased rates of adhesions
and fistulas.
b. shows lower wound strength than Marlex
c. may be placed as an underlay on bowel - offers a mechanical advantage
because the forces generated by intraabdominal pressure tend to hold the
patch in place.
d. when it becomes exposed, the lack of soft-tissue attachments causes
exudative fluid to dissect along the entire mesh, and the likelihood of
salvage with local means becomes quite low.
3. Vicryl mesh
a. remains in place for approximately 4 to 6 weeks, providing support
while granulation tissue forms in the wound.
b. Mainly indicated in contaminated wounds as a temporary measure
c. limited because of its association with ulceration, fistulas, and late hernia
formation
d. Ulceration is believed to occur secondary to ischemia resulting from the
restricted vascular perfusion of granulation tissue growing through mesh
e. As the wound contracts, wrinkles occur with resultant loss of coverage,
extrusion, and erosion.
Method
 An inlay, rather than interposition or onlay, technique has been reported to result
in a stronger abdominal wall repair due, in part, to continuous positive intraabdominal pressure ( In contrast, chest wall repairs are generally subject to
negative intrathoracic pressure and thus onlay preferred)
 Abdo pressure and muscle contraction can result in lateral distraction which can
lead to recurrence between the mesh and native fascia
- retro rectus repair space between the rectus muscle and the peritoneum. The
advantage of this is that the forces of the abdominal pressure pushes the
peritoneum and the post rectus fascia against the mesh, which is isolated from
the abdominal contents with the only chance of recurrence is at the superior
and inferior margins
- onlay graft to reinforce
 Management of recurrence usually involves placing more mesh in the abdomen.
Although this is usually successful, failure after 2 or 3 attempts warrants
consideration of alternative methods of closure.
 Mesh infection - options:
1. Opening the wound and treating it with dressing changes is successful in some
patients.
2. Resection of the nonincorporated mesh and implantation of a
bioprosthesis(Alloderm)
3. In patients who have failed conservative and minimal surgical management,
total mesh excision may be required. Reimplantation of mesh into this infected
field is not recommended
Biosynthetic
Alloderm (PRS Oct 2005)
 potential advantages of AlloDerm over other commonly used permanent prosthetic
mesh products include
1. minimal abdominal adhesions to the repair site,
2. remodeling with autologous, vascularized tissue,
3. resistance to bacterial infection.
4. may be used in irradiated fields
5. small areas of exposure are relatively simple to treat with local wound care.
 tensile strength of the implanted AlloDerm does not decrease and remains stronger
than native fascia
 One drawback is the need to splice together small pieces when a large mesh is
required
Autologous
Fascia lata graft
 lower risk of infection than synthetic mesh
 lack of tensile strength and contractility make fascia inferior to muscle flaps.
 Disadvantages:
1. Limited size
2. Donor site morbidity – muscle bulge, scar
3. stretches with time
Omentum
 advantages of being highly vascularized and of providing plentiful fat for
contouring.
 Disadvantages:
1. requires akin graft
2. lacks fascial support, requiring prosthetic material for strengthening.
Flap reconstruction
Fascio-cutaneous flaps
 primarily to repair partial defects of the skin and subcutaneous tissues.
 Upper 1/3rd
o Thoracoabdominal – limited arc of rotation
 Middle 1/3rd
o Iliolumbar bipedicled flap
 Lower 1/3rd
o Groin flap
o DIEA
Musculocutaneous flaps
 optimal choice for partial musculofascial defects of the lateral abdominal wall
greater than 3 cm in size.
 They provide fascial support as well as soft tissue cover and are usually used in
contaminated fields where nonabsorbable synthetic mesh cannot be used
 Flaps used :
1) TFL
2) Rectus femoris
3) Rectus abdominis
4) Lat dorsi flap
TFL flap
 Type I flap
 Large skin territory of 15x 40 cm can be used with the flap.
 Posterior border is a line from the greater trochanter to the lateral knee at the
margin of biceps femoris muscle and anteriorly the flap may include skin over the
rectus femoris
 Skin is reliable down to 10cm above the knee
 Reach to infraumbilical abdomen ipsilaterally (lower and middle 1/3rd)
 Disadvantages:
1) in the upper abdomen - the distal third of the skin island has a random blood
supply and thus unreliable( the blood supply in this area is usually from
perforators in the vastus lat)
2) the parallel fibres of the TFL are at a mechanical disadvantage if placed
vertically
3) limited by donor morbidity because harvesting more than 8 cm requires a skin
graft for closure.
Rectus femoris flap
 Type II – blood supply = descending branch of LCFA 7-10cm below pubic
symphysis
 can provide dense fascia and the overlying skin for abdo wall recon
 Preferred for suprapubic and lower abdo wall coverage because of the proximity
reliability and ease of elevation
 Less suitable than TFL for groin recon and doesn’t reach the upper abdo unless
used as a turnover
 associated with some donor morbidity, particularly weakening of quadriceps
function.
 Functional loss reduced if lat and medial vastus sutured to the rectus fem
 The cutaneous segment can be expanded to 3x the width of the RF by including the
adjacent fascia lata
 cutaneous portion of the rectus femoris flap may be unreliable.
 The muscle is 6cm width but the overlying fascia lata is strong enough to
reconstruct a defect 15-20 cm in diameter
 Pedicle is the limiting factor in flap mobility and division of the muscle doesn’t
facilitate the movement of the flap
 extended rectus femoris or “mutton chop” flap has been used successfully in the
epigastric region for massive defects.
Rectus abdominis
 Superiorly based pedicle flap is used for defects of the upper two-thirds of the
abdomen; the inferiorly based flap for defects of the lower one-third.
 The extended DIEA (EDIE flap) with bilobed closure is useful in large upper abdo
defects
 Can also be used as a turnover flap for midline defects
Latissimus Dorsi
 ideal for the repair of large lateral wall defects of the upper third of the abdomen.
 Transfer of the latissimus dorsi flap requires harvesting of the pregluteal fascia to
reach the abdominal midline - skin over this fascial ext is less reliable
Gracilis flap
 lower abdo and perineal recon
External oblique
Type IV flap
preferred for the upper two-thirds because of a limited arc of rotation and tenuous
blood supply.
Internal oblique
 Type V
 reaches the lower third of the abdomen and the groin.
 Use of this flap is hindered by the technical difficulty of dissection and
unreliability of the donor vessel
Vastus lateralis
 Type I
 used in the lower third of the abdomen
 has limited donor morbidity
 lacks a significant fascial component
Free flaps
 most popular recipient vessels include the inferior epigastric, deep circumflex iliac,
superior epigastric, internal thoracic, and saphenous vein loop grafts.
 Groin flap - Disadvantages of the free groin flap include inadequate myofascial
support for abdominal reconstruction and an unreliable pedicle.
 free innervated latissimus dorsi flap has been described as a means to re-establish
the contractile force and strength of the lost abdominal wall.
Reference
SRPS
Achauer
CME – abdo wall recon by R rorich , hobar , lowe