Biogradable Polymeric Biomaterials

Introduction

1. The biogradable has same meaning as other terms such as absorbable and resorbable. The biogradable polymers are those polymers which can be broken down through hydrolytic mechanism without the help of enzymes. The biogradable polymeric biomaterials have two major advantages which are: (1) These materials are absorbed by the body leaving no trace at the implant site. (2) These materials regenerate tissues and their implant is used as temporary scaffold for tissue regeneration.

TYPES

1. All biogradable polymeric biomaterials can be divided into eight groups based on their chemical origin as under:

(a) Biogradable linear aliphatic polyesters and their copoymers. This group of biogradable polymers are widely used in surgery. Polyglycolide polylactide, polycaprolactone and polyhydioxy buty rate are linear aliphatic polysters . The copolymers are formed through copolymerisation of the members of this linear aliphatic polysters are also included in this group.

(b) Biogradable copolymers obtained from copolymerisation between linear aliphatic polysters and monomers other than linear aliphatic polysters.

(c) Polyanhydrides

(d) Polymerisation of orthoesters.

(e) Polymerisation of ester–ethers.

(f) Polysaccharides which are biodegradable such as hyaluronic acid and chitin.

(g) Polyaminoacids

(h) Inorganic biogradable polymers having nitrogen - phosphorous linkage instead of ester linkage.

Applications

1. The widely used biomedical application of biodegrable polymeric biomaterial has been in wound closure. These biomaterials are based either upon the glycolide or the lactide family. Their degradation with time and environment is very important. These biomaterials are used as surgical meshes for hernia and body wall repair.

2. The next largest biomedical application of biodegradable polymeric biomaterials is in drug control and release in devices. Polyanhydrides and orthoester polymers are these types of biodegradable polymers which are used to prepare a drug depot which would last for a few months.

3. Biodegradable polymeric biomaterials particularly totally resorbable composites have recently been used in the field of orthopaedics as PDS pins for the fixation of internal bone fracture.

4. Biodegradable polymeric biomaterials are also used as vascular grafts and stunts, nerve growth conduits, augmentation of defected bone, ligament and tender prostheses and intramedullary plugs for total hip replacement.

5. Biodegradable polymeric biomaterials have a controlled in vivo degradation. The material must be biodegradable, and its degraded products should be easily absorbed by the body without any toxic effects. The rate of degradation of the material should match the demand of the end use to which it will be put. Bioabsorbable sutures is one of such application.