Question

Q7. Given application prioritize which properties are most important and explain why.

You are evaluating a new material for a hernia support mesh. This device holds internal organs in position until healing is completed after surgery. Which 3 material properties would you evaluate first and why? Set approximate minimum values for each as well when possible.

Q8. Compare and contrast the atomic, lattice, micro and bulk structures of similar materials and explain how they influence the properties of the material.

How do the structures of low density polyethylene and ultra-high molecular weight poly(ethylene) differ at the atomic, lattice, micro, and bulk levels? How do these differences in structure produce different material properties?

Answer 1

Ans.7-The use of prosthesis has become essential for repair of all hernias since the recurrence rates are consistently lower when they are used. To fulfill this requirement, a variety of newer meshes have been engineered. An ideal prosthesis should be strong, pliable, non-allergenic, inert, non-biodegradable, non-carcinogenic and should stimulate adequate fibroblastic activity for optimum incorporation into the tissues. Prosthesis used for hernia repairs can be non-absorbable, composite (combination of absorbable and non-absorbable fibres) or with an absorbable or a non-absorbable barrier.   Surgeons should acquire sufficient knowledge of different types of prosthesis so as to select an appropriate one for a given case. Non-absorbable or composite mesh is recommended for hernia repair where it will not come in contact with the bowel. Prosthesis with a barrier only should be used for intra-abdominal placement to prevent bowel adhesions since it is increasingly difficult to defend the use of a biomaterial that has no adhesion barriers. This review highlghts all these different types of meshes and their appropriate selection for a given hernia repair. Selection of the optimum size and its proper fixation is mandaory. Complications can be avoided or minimized with proper selection of mesh for a given case and by performing the surgery with a meticulous technique.