Incisional Hernias: A Paradigm for Human Wound Healing

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Incisional Hernias A Paradigm for Human Wound
Healing
Adrian Barbul MD, FACS Department of
Surgery Sinai Hospital of Baltimore and The
Johns Hopkins Medical Institutions
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WOUND HEALING
INJURY
COAGULATIONPLATELETS
COMPLEMENTKININS
MIGRATION/PROLIFERATION
INFLAMMATION
FIBROBLASTS
GRANULOCYTES MACROPHAGES LYMPHOCYTES
RESISTANCETO INFECTION
KERATINOCYTES
CONTRACTION
ENDOTHELIAL CELLS(ANGIOGENESIS)
DEBRIDEMENT
PROTEOGLYCANSYNTHESIS
COLLAGENLYSIS
COLLAGENSYNTHESIS
REMODELING
HEALED WOUND
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COMPONENTS OF WOUND HEALINGSequence
Coagulation
Inflammation
Migration/Proliferation Angiogenesis Epithelizatio
n Contraction Fibroplasia
Remodeling
Witte MB, Barbul A. Surg Clin North Am.
199777509-528.
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COMPONENTS OF WOUND HEALING
Cell Types Involved
CoagulationProcess
Platelets
Platelets Macrophages Neutrophils
InflammatoryProcess
Macrophages Lymphocytes Fibroblasts Epithelial
cells Endothelial cells
Migratory/ProliferativeProcess
RemodelingProcess
Fibroblasts
Injury
Hours
Days
Weeks
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REGENERATION vs SCAR FORMATION
Amoeba
Newt
Human
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COLLAGEN

• unique AA - OH-proline, OH-lysine (hydroxylation
  requires vit C)
• every 3rd AA - glycine
• scar - type I and III collagen

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REMODELING

• Changes in physical properties of extracellular
  matrix

l
WoundBreakingStrength
l
n
TotalCollagen Content
n
n
l
n
n
l
n
l
n
7
14
21
28
35
42
Days Postwounding
Adapted with permission from Madden JW and
Peacock EE Jr. Ann Surg. 1971174517.
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REMODELLING PHASE

• collagen equilibrium (synthesisdegradation)
• wound collagen maximal _at_2-3 weeks
• tensile strength? steadily
• restoration of nl adult collagen
  phenotype (typeItype III - 41)
• ? alignment of fibrils
• ? proteoglycan

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REMODELING

• Changes in matrix composition over time

Extracellular matrix
Collagen
Scar
Adapted with permission from Greenfield LJ, ed.
Surgery. 2nd ed. Lippincott-Raven Publishers,
1997.
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SCAR WARS

• FAILURE dehiscence, herniation
• EXCESS -keloids, hypertrophy

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HEALING PROCESS ACUTE WOUNDS

• Sequence completed in continuous and expected
  time frame
• Usually achieved with few or no complications
• Overreaction in acute wound healing
• Keloids
• Hypertrophic Scarring

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Continuum between Normal and Impaired Healing
Normal Healing
Delayed Healing

Impaired Healing/Chronic Wound
TIME
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Healing Deficits

• Delayed Healing
• Nutritional Deficiencies
• Trauma
• Sepsis

• Impaired Healing
• Diabetes
• Steroids
• Radiation

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Acute Wound Failure
Fistula

• Dehiscence/Incisional hernias
• Anastomotic disruptions/GI fistulae (5-30)
• Vascular pseudoaneurysms
• Bone non-fusion
• Spine surgery
• Sternotomy

Hernia
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WOUND DISRUPTIONS
DEEP
COMPLETE
SUPERFICIAL
(INCISIONAL HERNIA)
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INCISIONAL HERNIA Definition

• bulge noticeable on standing, by patient or
  observer, and frequently requiring support or
  repair - AV Pollock 1977
• anatomically a separation of the deep
  musculo-aponeurotic layers with intact overlying
  skin by definition a prior surgical incision is
  present a true hernia sac exists

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Ventral Hernia Confusion

• Developmental defects exist
• No prior surgical intervention

Supraumbilical Lumbar
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Abdominal WallStructure and Function

• Maintain upright posture
• Support spine
• Contain/ Protect abdominal organs
• Stabilize pelvis, ambulate
• Valsalva
• Bowel function
• Cough

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Incisional Hernias Anatomy

• Embryologically
• Ectoderm and mesoderm
• Coelomic tube
• Ventral midline linea alba
• Skin, FASCIA, muscle, peritoneum

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Incisional Hernias The Problem

• 11 of 4x106 abdominal wall closures in US fail
  resulting in 400,000 new cases
• National Center for Health Statistics, National
  Hospital Discharge Database 1996
• 2.5 Billion Cost
• J Am Coll Surg 188429-447, 1999
• gt200,000 Ventral Hernia Repairs Annually
• National Hospital Discharge Database, 1995

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Incisional Hernias Incidence


WOUND DISRUPTION
POST-ABDOMINAL PROCEDURES
POST-ABDOMINAL PROCEDURES
Year
Author
Incidence ()
Year
Author
Incidence ()
1965
Efron
3.0
1965
Efron
3.0
1968
Lehman
2.5
1968
Lehman
2.5
1970
Mendoza
2.2
1970
Mendoza
2.2
1973
Keill
1.1
1973
Keill
1.1
1979
Penninckx
2.6
1979
Penninckx
2.6
1979
Greenberg
0.51
1979
Greenberg
0.51
1982
Bucknall
1.7
1982
Bucknall
1.7
1992
Riou
1
1992
Riou
1
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INCISIONAL HERNIAS
Early mechanical wound failure?

• Metal clips mark fascial edges
• AXR on POD 30
• Greater than 12 mm fascial separation by POD 30
  94 incisional hernia rate at 3 years

Pollack Evans, Br J Surg 76953-54, 1989
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Incisional Hernias Time of Occurence


564 Laparotomies
Mudge Hughes-BJS 7270, 1985
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Incisional Hernias Time of Occurence
2983 Laparotomies

Hoer - Chirurg 73474, 2002
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Incisional HerniaDemographics

• Older population (mean age 59 yrs)
• 6040 female preponderance

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Incisional Hernias Pathophysiology

• Tend to enlarge
• Loss of intra-abdominal pressure results
  in-respiratory dysfunction-mesenteric
  edema-splanchnic venous congestion
• Muscle atrophy
• Skin atrophy, ulceration

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Incisional Hernias Pathophysiology

• Pain
• Visceral
• Spinal
• Loss of domain
• Visceral incarceration, strangulation
• Cosmesis

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Mechanism of Incisional Hernias?

• Early response and public stance..its the
  patients fault!

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Incisional Hernia Systemic Factors

• Age
• Malnutrition
• Diabetes
• Obesity
• Smoking/COPD
• Drugs (steroids)
• CRF
• often discounted when closing

10
young
old
5

0
Incision BS
Petersen et al - Eur Surg Res 27250, 1995
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Incisional Hernia Systemic factors

• Malnutrition
• usually mixed type (PCM) - if uncomplicated it
  delays healing
• PCM in conjunction with other risk factors
  impairs wound healing
• increases susceptibility to wound infections
• nutritional intervention leads to rapid
  resolution - route does not matter

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Nutrition and Wound Healing
Recent Food Intake OHP Content of Human
Experimental Wounds




Adequate
Inadequate


Weight loss () 91 111




Windsor JA BJS 75135, 1988
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Incisional Hernia Dysnutrition

• Obesity is a major and growing problem
• Associated with X3 increase in incidence
• Fatty infiltrated tissues dont hold sutures well
• Increased tension on suture line from fatty
  panus

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Incisional HerniaLocal Obstacles to Healing

• Technical factors-incision
• -suture-type of closure
• Wound necrosis
• Tissue hypo-perfusion

• Wound infection
• Hypoperfusion
• Trauma
• abdominal pressure

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Incisional HerniaLocal Obstacles to Healing

• if wound infection occurs, rate of herniation is
  4-5x higher
• 40-50 of pts with incisional hernia have had
  post-op wound infection
• infection diminishes wound collagen deposition
  and increases collagenolysis

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Incisional HerniaInfection

• Wound infection
• Invasive micro-organisms
• ?-hemolytic Strep.
• gt 105 per gram tissue
• Wound necrosis
• Dysregulated PMN and/or macrophage activity
• Foreign bodies

PTFE Mesh
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Incisional HerniaSurgical Site Infection
HOST DEFENSE
BACTERIA
WOUND
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Incisional HerniaLocal Obstacles to Healing

• Technical factors-incision
• -suture-type of closure
• Wound necrosis
• Tissue hypo-perfusion

• Wound infection
• Hypoperfusion
• Trauma
• abdominal pressure

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Incisional herniaIntra-abdominal pressure

• increases appreciably with straining, coughing,
  vomiting, distension, pregnancy
• Role of NG decompression in colorectal cases
• 251 cases w/NG 3.2
• 229 cases w/out NG 6.6

Otchy - Dis Colon Rectum 38604, 1995
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Mechanism of Incisional Hernias?

• Late, more thought-out and private response or at
  MM
• ..Its the surgeons fault!

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Incisional HerniaLocal Obstacles to Healing

• Technical factors-incision
• -suture-type of closure
• Wound necrosis
• Tissue hypo-perfusion

• Wound infection
• Hypoperfusion
• Trauma
• abdominal pressure

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Incisional HerniaIncision

• muscle splitlttransverse ltparamedian ltmidline (all
  cases)
• In controlled studies, incision location does not
  play a role in elective cases
• AAA- Lord - JVS 20271, 1994
• Transverse 16.5
• Midline 13.4
• higher incidence with repeat incision

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Incisional HerniaIncision

• Post-gyn laparoscopy - 21/100,000 (10mm trocar
  site - 0.23
• 12mm trocar site - 3.1)
• Post laparoscopic cholecystectomy - 0.77

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SUTURE CHARACTERISTICS

• TENSILE STR COMPLETE
• TYPE CLASS MATERIAL _at_14 days
  ABSORPTION
• Catgut Absorb Collagen 0 (7-28 days)
  70
• Dexon Absorb Polyglycolic acid 65
  60-90
• Vicryl Absorb Polyglactic acid 60
  60-90
• PDS Absorb Polydioxanone 70
  180-210
• Maxon Absorb Polyglyconate 75
  180
• Steel N/absorb Fe/Ni/Cr 100
  none
• Silk N/absorb Protein 100
  2 yrs
• Nylon N/abosrb Polyamide 100
  none
• Prolene N/absorb Polypropylene 100
  none

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Incisional herniaSuture

• INCIDENCEAbsorbablegtslowly absorbablenon-absorba
  ble
• PAIN, SUTURE SINUS FORMATIONnon-absorbablegtslowly
  absorbable

vant Riet -BJS 891350, 2002
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Effect of infection and suture type on
rat laparotomy bursting pressure (mmHg)


Effect of infection and suture type on rat
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THE SUTURE BREAKS
THE KNOT UNTIES
THE SUTURE CUTS THROUGH
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Non-absorbable sutures Key-hole defects
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Characteristics of ideal surgical suture

• Holds parts together
• Disappears when its work is finished
• Is free from infection
• Non-irritant

Moynihan, 1920
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INCISIONAL HERNIA Type of Closure
INCISIONAL
HERNIA


T

• Mass closure has less hernia formation than layer
  closure
• Closure of peritoneum not important
• Interrupted vs running
• no difference in elective cases

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INCISIONAL HERNIA Type of Closure
INCISIONAL
HERNIA


T

• Suture lengthincision length ratio gt 41

L0
Lt
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Repair of Incisional Hernia
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Incisional HerniaPrinciples of Repair - Pre-Op

• Never an emergency except if incarceration/strangu
  lation occurs
• Optimal preparation of patient including weight
  loss, smoking cessation, chest PT, resolution of
  all infections.

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Incisional Hernia Intra-op Principles of Repair

• Always check for other defects
• Liberal use of drains
• Tension-free repair
• Prosthetics appear superior
• Approach

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Incisional herniaForces at work

• in cadavers-anterior rectus sheath 2.93Kg-ful
  l thickness musculo-aponeurosis 3.93Kg-linea
  alba 7.93Kg
• At operation, use force of 0.5-1.5 Kg to pull
  aponeurosis

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Collagen fibers oriented transversely
Distractive forces
2-layers
Laterally based innervation
Laterally based blood supply
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Open Incisional Hernia Repair
Omentum
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Component Separation
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Incisional Hernia Intra-op Principles of Repair

• Always check for other defects
• Liberal use of drains
• Tension-free repair
• Prosthetics appear superior
• Approach

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Incisional HerniaMesh Repair

• lesser inflammatory response, less tissue
  ingrowth Absorbable prosthesis (Dexon/Vicryl)
  only for temporary closure
• Permanent Prostheses-Marlex/Dacron - intense
  inflammatory response, enhances scar formation
• -PTFE mesh -

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Incisional HerniaMesh Repair

• Minimized, low-weight (26.8g/m2) with large pore
  size (5mm) superior to standard , heavyweight
  (90.2g/m2), small pore size (0.8mm) polypropylene
  mesh)(Schumpelick - Chirurg 70422, 1999)
• Assure sufficient overlay
• Staple vs Suture
• Do not apply mesh onto exposed bowel
• Do not use mesh in face of infection

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Incisional HerniaMesh Repair
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Its better to have a hernia than a fistula
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Incisional HerniaMesh Repair

• Superior to primary repair 23 vs 46 recurrence
  (Luijendijk NEJM 343392, 2000)
• Significant rate of recurrence

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Incisional HerniaMesh is not the answer to
recurrence
(Flum - AnnSurg 237129, 2003)
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Incisional HerniaPrinciples of Repair- Intra-op

• Always check for other defects
• Liberal use of drains
• Tension-free repair
• Prosthetics appear superior
• Approach

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LAPAROSCOPIC REPAIRS
Jury is still out.
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Incisional HerniaResults

• Results are dismal
• 417 repairs
• 10 36
• 20 56
• 30 48
• 40 47

Hesselink - SGO 176228, 1993
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Incisional Hernia - Results
(Flum - AnnSurg 237129, 2003)
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Mechanism of Incisional Hernias?

• Reality is that both factors, patient and
  surgeon, contribute, but
• biology gtgt technique whos fault is it?

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WOUND HEALING
INJURY
COAGULATIONPLATELETS
COMPLEMENTKININS
MIGRATION/PROLIFERATION
INFLAMMATION
FIBROBLASTS
GRANULOCYTES MACROPHAGES LYMPHOCYTES
RESISTANCETO INFECTION
KERATINOCYTES
CONTRACTION
ENDOTHELIAL CELLS(ANGIOGENESIS)
DEBRIDEMENT
PROTEOGLYCANSYNTHESIS
COLLAGENLYSIS
COLLAGENSYNTHESIS
REMODELING
HEALED WOUND
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Investigational Strategies

• Prevent primary incisional hernias
• Improve on dismal results of incisional hernia
  repairs

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Incisional herniaCollagen Metabolism

• Decreased type ItypeIII collagen synthesis in
  skin and fascial fibroblasts
• Increased MMP 1 expression
• Increased CTGF
• Decreased tenascin
• collagen gene polymorphism

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Incisional Hernia Model
Availability of an experimental model
Fascia celiotomy
Skin flap
5 cm
5-0 plain catgut
U. Michigan
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Incisional HerniasSummary

• Most often result of acute wound failure
• iatrogenic
• No improvements on high incidence
• Debilitating and high risk for repair
• Expensive

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