Page 42 - herina surgery and possible lawsuits

Factors affecting the biological response of prosthesis:

The factors those affect the biological response assist the surgeon in choosing
prosthetic. Following variables may be useful in determining the choice prosthesis.

(1) The raw material used to make the prosthetic
1. Synthetic nonabsorbable

2. Coated nonabsorbable
3. Partially nonabsorbable
4. Biological
(2) The prosthetic’s design

i. Density (weight) - g/m2
The weight of the mesh depends on both the weight of the polymer and the

amount of material used (pore size).[82]
Thickness and weight were used to classify mesh as follows:[81]
1. Heavy weight >80 g/m
2. Medium weight: 50-90 g/m2

3. Light weight. 35-50 g/m2
4. Ultralight weight: <35 g/m2
Heavy weight meshes have thick polymer, small pore size and high tensile

strength, which activate a profound tissue reaction and dense scarring. Whereas
light weight have thinner filaments, larger pores > 1 mm, activate less pronounced
foreign body reaction and are more elastic, able to withstand pressure maximum

intra abdominal pressure. [82]
At present polypropylene prostheses are being modified into prostheses made with
less material, with large pores and a tighter spatial organization of filaments,

u. Porosity • Porosity is the mam determinant of tissue reaction.
1. Very large pore: >2000 pm
2. large pore: 1000-2000 pm
3. Medium pore: 600-1000 pm

4. small pore: 100-600 pm
5. Microporous (solid): <100 pm
Pores must be more than 75 pm in order to allow infiltration by macrophages,

fibroblasts, blood vessels and collagen. [82]

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