HERNIAL PROSTHESES

MODERATORS -

PROF DR H K BHATTACHARYA

PROF DR R K DEKA

PROF DR A AHMED

PRESENTED BY –

DR AYMEN AHMAD KHAN

WHAT IS HERNIA

Hernia is derived from the Latin word for rupture.

A hernia is defined as an abnormal protrusion of a part or whole of the viscus through the wall of its containing cavity

Its content may be any abdominal viscera, most frequently the small bowel and omentum.

When protruding through the hernial ring, the herniated structure is covered by the parietal peritoneum, here called hernial sac.

Although hernias can occur in various regions of the body, the most common site is the abdominal wall, particularly in the inguinal and ventral regions

Mainly places of abdominal wall hernia: Epigastric (E); Umbilical (U); Hypogastric(H); Inguinal (I).

Hernias of the groin area: Indirect (I); Direct (D); Femoral (F).

Schematic drawing of a hernia. In this case, the bowel is the herniated viscera.

Schematic drawing of a normal abdominal wall and their layers: Skin (S); Fat Tissue (F); Aponeurosis (A); Pre-peritoneal Fat Tissue (F); Peritoneun (P); and the abdominal viscera (V).

TREATMENT OPTIONS FOR HERNIA

merely correcting the hernia defect with sutures does not avoid the source of the problem, because the patient’s tissues will still be fragile and predisposed to rupturing again at the same site. The recurrence rate for ventral hernia may be as high as 40–54% after open repair without meshes

Mesh repair is superior to suture repair, results in a lower recurrence rate and less abdominal pain.

For each type of hernia there are several techniques involving prostheses and different models of prosthesis.

To help the surgeon choose, it is helpful to look at the prosthetic landscape with a perspective based on

(1) the prosthetic’s raw material and design,

(2) the implantation technique

(3) the clinical scenario

For treating inguinal hernia, the use of a polypropylene prosthesis is the best technique.

Endoscopic inguinal hernia techniques result in a lower incidence of wound infection, hematoma formation and an earlier return to normal activities or work than the Lichtenstein technique. When only considering chronic pain, endoscopic surgery is superior to open mesh.

However, endoscopic inguinal hernia techniques need general anesthesia, result in a longer operation time and a higher incidence of seroma than the Lichtenstein technique

For fixation of the mesh in ventral hernia repair, most authors have used sub-lay technique. Which can be extraperitoneal and intraperitoneal.

In sub lay technique the mesh is sutured into place on the posterior rectus sheath with approximately 4 cm of fascia overlap

The other two repair options include an inlay technique such that the mesh is sutured to the fascial edges, and an onlay technique whereby the mesh is placed and sutured onto the anterior rectus sheath

The inlay technique has the advantage of minimal soft-tissue dissection thus reducing devascularized tissue, but the disadvantage of high rate of recurrences, while the onlay technique has the disadvantage of vast soft tissue dissection above the rectus layer.

Inlay Onlay

INTRODUCTION An abdominal wall hernia may be repaired by closing the hernia

defect under tension with sutures or its reinforcement with mesh.

The suture repair is characterized by high recurrence rates.

Mesh repair is superior to suture repair, results in a lower recurrence rate and less abdominal pain.

Mesh helps to replace the deficient tissue and reinforce weak tissue

It provide the surgeon with the ability to achieve a durable, tension free repair.

IDEAL HERNIAL PROSTHESIS

Should be strong but pliable and easy to handle.

Should be inert, non allergic , non biodegradable and non carcinogenic

Should have optimum thickness ( since density determines tissue reaction)

Should stimulate adequate fibroblastic activity and gets rapidly incorporated into the tissues.

Should achieve early, rapid and optimum ingrowth of fibrocollagenous tissue to prevent migration or dislocation.

Should preferable be macroporous, monofilament, transparent and resist infection

Should provide barrier to adhesions in intra abdominal placements.

So far no single mesh fulfils all the criteria.

PHYSIOLOGICAL RECONSTRUCTION

Mesh implants provides bio mechanical strength to attenuated fascial tissue.

It is designed to withstand the tension forces acting on the abdominal wall.

Mesh does not imepede but actually facilitate the healing process of the hernia defect by encouraging ingrowth of body’s own connective tissue by induction of strong collagen tissue around mesh.

Large pore size mesh offers advantage over traditional small pore mesh, is that tissue is able to grow through the large pores of the mesh and create a thinner more integrated scar . Thus ultimately creates a more “ Elastic Scar”

TYPES OF PROSTHESES

Commoly used prostheses for repair of hernia are

1: Polypropylene

2: Polyester

3: PTFE (polytetrafluroethylene)

POLYPROPYLENE MESH It is most widely used because of its stability, strength, inertness and handling

qualities.

The mesh is made of prolene fibers arrange in a network with pores of different sizes

The product differs with different manufactures regarding size of monofilament material, size of pores, its thickness , pliability and shrinkage

Initially fibers were woven but later changed to knitted construction to prevent unravelling of cut edges of the mesh.

Monofilament is preferred as it is less likely to give infection.

All implanted meshes showed an increased stiffness of abdominal wall. Light weighted meshes results in less restriction of abdominal wall compliance while providing more adequate strength for repair of ventral hernia.

Example are- Marlex , PROLENE soft and surgipro

PHS ( prolene hernial system ) and a plug. It is indicated for open technique for groin,

epigastric and umbilical hernia.

Plug is implanted in deep inguinal ring.

PHS has 3 parts-

1. underlay

2. connector

3. onlay

POLYESTER

They are not very popular with laparoscopic surgeons though they are widely used in FRANCE

They are mainly used for Stoppa Technique

The Stoppa Repair is a tension free type of hernia repair. It is performed by wrapping the lower part of the parietal peritoneum with prosthetic mesh and placing it at a preperitoneal level over myopectineal orifice. It was first described in 1975 by Rene Stoppa. This operation is also known as giant prosthetic reinforcement of the visceral sac (GPRVS).

The MPO is simply a layer of non-muscular Connective Tissue called "Transversalis Fascia", consisting of two thin and adherent semi-layers. The MPO is bordered:

1. Above by the arching fibers of the internal oblique and transversus abdominus Muscles

2. Medially (towards the center or to the right) by the Rectus Abdominus Muscle and its fascial Rectus Sheath

3. Inferiorly by Coopers Ligament, and

4. Laterally by the Ileopsoas Muscle

Myopectineal Orifice of Fruchaud (MPO)

POLYTETRAFLUROETHYLENE MESH ( PTFE )

They are soft , smooth and strong.

They are suitable for repair of all groin and ventral hernias by open as well as laparoscopic technique.

They are avoided for intraabdominal placements as there are reports of complication of bowel adhesions, obstruction , fistulisation and erosion into abdominal visceras.

COMPOSITE MESHES

1.Light weight composite meshes without adhesion prevention barrier

2.New composite meshes with adhesion prevention barrier ---

a> Absorbable barrier composite mesh

b> Non absorbable barrier composite mesh

Lightweight Composite Meshes Without Adhesion Prevention Barrier

When polypropylene material is reduced in the mesh , its handling become difficult. The handling is improved by incorporating absorbable filaments of polyglactin 910 ( Vicryl ) or poliglecaprone (Monocryl )

These filaments are twisted together and then knitted to form a requisite mesh structure

They are partially absorbable since they have 50 percent Vicrly or Monocryl

They are macroporous , this induce better tissue ingrowth of strong three dimensional collagen fiber network.

The construction results in almost 70% reduction of implanted foreign body and results in “ scar mesh “

Bio compatibility of mesh increase with low density, low weight , large pore size and mono filament construction.

New Composite Meshes With Adhesion Prevention Barrier

They are used in intra peritoneal placement of mesh. Therefore requires a material which has both high tissue ingrowth towards abdominal wall and non adhesiveness on other side to prevent bowel adhesions.

In these meshes layer facing abdominal cavity prevents adhesions with bowel by allowing the formation of neo peritoneum, while layer in contact with abdominal wall encourages high tissue in growth

They are of 2 types -

a> absorbable barrier composite mesh

b> non absorbable barrier composite mesh

Absorbable Barrier Composite Mesh

1: Sepramesh Composed of macroporus polypropylene on one side with

bioresorbable , non immunogenic membrane of sodium hyluronate and carboxymethylcellulose on other side

Macroporus polypropylene layer in contact with abdominal wall encourages high tissue in growth.

The absorbable barrier turns to gel in 48 hrs, remains for approx. 7 days and is cleared from body in 28 days. This anti adhesive material forms a physical barrier on damaged surfaces to prevent adherence.

Sodium hyaluronate and carboxy methylcellulose are anionic polysaccharides that form a membrane that is negative charged which promotes the separation of healing tissues

2: Parietex Composite : Composed of multifilament polyester mesh with purified, oxidised bovine

atelocollegen type 1 coating covered by an absorbable , anti adhesion film of polyethylene glycol and glycerol

Polyethylene glycol is hydrogel that decreases tissue adherence and glycol is hydrophobic lipid. They form a membrane to prevent bowel adhesions.

The collagen, polyethylene glycol and glycerol film is resorbed in approx. 3 wks

3 : Parientene composite : It consists of same antiadhesive barrier but coated to polypropylene

4: Proceed surgical mesh

It is laminated mesh composed of oxidised regenerated cellulose ( ORC ) fabric, prolene soft mesh , a non absorbabale polypropylene mesh which is encapsulated by polydioxanone polymer.

The polypropylene mesh allows for tissue ingrowth while ORC side provides a bioresorbable layer that physically separates the polypropylene mesh from abdominal viscera during wound healing period to minimize tissue attachment to mesh.

Polydioxanone provides a bond to ORC layer.

It leaves behind less residual foreign body, and does not harbour bacteria

Non absorbable barrier composite meshA> Bard Composix Mesh : Consists of sheet of Marlex with thin layer of ePTFE on one surface.

The PPM side is attached to the abdominal wall and the ePTFE surface will contact the bowel.

It provide good tissue incorporation on PPM surface while diminishing the chances of abstruction and fistulisation.

B> GORE – TEX Dual mesh : Has 2 surfaces : one is very smooth ( microporous 3mm) and other

side is rough ( micropores 22mm)

It is implanted with smooth surface against visceral organs and rough surface against ehich tissue incorporation is desired

Mechanism Of Biomaterial Integration To The Organism

A> Normal healing After tissue injury, such as surgery, the healing

process occurs. It takes place in three phases :

Inflammatory, substrate or exudative phase, characterized firstly by vasoconstriction and platelet aggregation. Fibrin is formed as the coagulation mechanism continues, in order to diminish loss to hemorrhage, and it lasts approximately 15 minutes.

The cell response is processed 6 to 16 h after the onset of the lesion, when a large amount of polymorphonuclear neutrophils appear, as the first wave of cell migration. They stay from 3 to 5 days, with a peak within 68 h . These are macrophage precursors.

Neocapillary growth and fibroblastic proliferation begin about 36 h after injury. The activated macrophages are the predominant leukocytes on day 3, when they peak and persist until healing is complete. This first phase lasts until the 2nd day , and may last until the 4th day postoperatively .

Around the 3rd to 5th day the proliferative or connective tissue phase begins. in which angiogenesis and fibroplasia occur, from the proliferation of the endothelial cells and fibroblasts, respectively. They will build the granulation tissue. The lymphocytes appear around the 5th day, peaking on the 7th day , and they are mostly represented by T Lymphocytes.

During the 2nd week, the fibroblasts become the dominant cells, especially on the 10th day. After this period they differentiate into fibrocytes. Fibroblasts synthetize collagen, which promotes repair resistance.

The fibroblasts migrate into the wound from the surrounding tissue, differentiating into myofibroblasts, forming actin filaments, synthetizing a collagen .

Wound contraction is an essential aspect of healing. It diminishes the area of the defect making it easier to close

From the 21st day onwards, during the last phase of the healing process, called molding, maturing, resolutive or differentiation phase, tension resistance will reach its highest levels. The accumulation of collagen tissue peaks on the 21st day, and its value remains practically constant in the 3 following months.

In the mature matrix type I is 80% to 90%, and type III is 10 to 20% of the total collagen. This matrix undergoes continuous modification until a stable matrix is formed. The scar tissue takes on 40% of the tensile resistance around 6 weeks, 80% around 6 months, and its maximum resistance is achieved after many months, or even years, but it is not equal to the resistance of healthy tissue

B> Healing With A Prosthesis

Immediately after implantation, the prosthetic adsorbs proteins that create a coagulum around it. This coagulum consists of albumin, fibrinogen, plasminogen, complement factors, and immunoglobulins.

Platelets adhere to this protein coagulum and release a host of chemoattractants that invite other platelets, polymorphonucleocytes (PMNs), fibroblasts, smooth muscle cells, and macrophages to the area in a variety of sequences.

The presence of a prosthetic within a wound allows the sequestration of necrotic debris, slime-producing bacteria, and a generalized prolongation of the inflammatory response of platelets and PMNs

Macrophages then increasingly populate the area to consume foreign bodies as well as dead organisms and tissue. These cells ultimately coalesce into foreign body giant cells that stay in the area for an indefinite period of time.

The fibroblasts and smooth muscle cells subsequently secrete monomeric fibers that polymerize into the helical structure of collagen deposited in the extracellular space.

The overall strength of this new collagen gradually increases for about 6 months, resulting in a relatively less elastic tissue that has only 70% to 80% of the strength of the native connective tissue

Biological mesh When should a biological mesh should used instead of

synthetic mesh?

Biological mesh are used when synthetic mesh are contraindicated as synthetic materials do not support vascular ingrowth and are susceptible to infections.

Biological mesh supports angiogenesis into collagen matrix , so delivery of WBCs and antibiotics are possible. The collagen scaffolding supports native fibrobast ingrowth and collagen deposition.

Later scaffolding is completely degraded , eventually allowing for bacterial removal.

Biomesh Type Products, Manufacturers

Human acellular dermis AlloDermЁ, LifeCell

Flex HDTM, J&J

AlloMaxTM, Davol

Xenogenic acellular dermis PermacolTM (porcine), Tissue Science Laboratories

SurgiMendTM (bovine,calf), TEI Biosciences

CollaMendTM, (porcine) Davol

XenMatriXЁ (porcine), Brennen Medical LLC;Brennenmed.com

StratticeTM, LifeCell

Porcine small intestinesubmucosa

SurgisisЁ, Cook Medical

FortaGenЁ, Organogenesis

LifeCell Alloderm AlloDerm®

Cadaveric tissue

Limited sizes

High cost

Well established

Not regulated by FDA as a medical device

Claims are extreme

Migration from other surgical areas was natural

FortaGen Organogenesis

Porcine derived tissue : crosslinked collagen

Begin to infiltrate with cells by 30 days post-implant

Are substantially remodeled by 6 months

Are well-integrated at the suture line (provides a lasting graft-host tissue interface not dependent on permanent sutures)

Do not elicit a foreign body response

Are as strong as adjacent host tissue at 360 days

Do not re-herniate

Fixation Of Mesh

For intra abdominal placement of mesh , few strong sutures should be placed at least at 4 corners of the mesh.

Tackers should not protrude too much beyond the mesh as these can cause adhesion to a bowel loop. Trackers penetrate only 2mm beyond the mesh and do not provide same holding strength as sutures. Tensile strength of sutures is 2.5 times greater than tackers

Full thickness abdominal wall suture fixation is necessary to prevent migration of mesh.

Tackers fixes the mesh to the peritoneum only and not directly to the fascia.

DOUBLE CROWN TECHNIQUE : tackers are initially placed 1 cm apart at edge of the mesh and a second inner crown of tackers is placed 1 cm apart at the edge of the defect. Abdominal wall is pressed down when tackers are applied.

Complications

PAIN : fixation of mesh with sutures by laparoscopic technique for ventral or incisional hernia repair can be painful initially. Pain resolves over time.

SEROMA : most commonly occurrence and resolve over a period of time.

URINARY BLADDER INJURY

BOWEL ADHESIONS

BOWEL OBSTRUCTIONS

BOWEL FISTULIZATION

EROSION INTO INTRA ABDOMINAL ORGANS

MIGRATION OF THE MESH

RECURRENCES

SUMMARY

Polypropylene mesh preferably light weight composite mesh should be ideal for open groin hernias, small ventral hernia and for TAPP and TEP.

Prosthesis with either an absorbable or a non absorbable barrier are used for intra abdominal placements as they prevents bowel adhesions.

Mesh should be of proper size to compensate for shrinkage

Mesh should be properly fixed to prevent dislodgement and migration.

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