Implantable polytetrafluoroethylene PTFE

F 754 Specification for Implantable Polytetrafluoroethylene (PTFE) Polymer Fabricated in Sheet, Tube, and Rod Shapes... 

The best known fluorocarbon polymer is polytetrafluoroethylene (PTFE), commonly known as Teflon (DuPont). Other polymers containing fluorine are polytrifluorochloroethylene (PTFCE), polyvinylfluor-ide (PVF), and fluorinated ethylene propylene (FEP). Only PTFE will be discussed here since the others have rather inferior chemical and physical properties and are rarely used for implant fabrication. 

Commonly used natural fibres are cotton and silk, but also included are the regenerated cellulosic fibres (viscose rayon) these are widely used in non-implantable materials and healthcare/hygiene products. A wide variety of products and specific applications utilise the unique characteristics that synthetic fibres exhibit. Commonly used synthetic materials include polyester, polyamide, polytetrafluoroethylene (PTFE), polypropylene, carbon, glass, and so on. 

Charnley develops the technique of low friction arthroplasty (LFA). Usirig polytetrafluoroethylene (PTFE) as the bearing material (Charnley 1961) implants were fabricated either by Charnley in his home workshop or in the machine shop at Wrightington and chemically sterilized. 

The unique invention that led to PTFE polymer products expanding and becoming desirably porous made the material suitable for use as implants. The modified structure consists of nodes interconnected by very small fibrils (Fig. 1.11). Briefly, the process is as follows. A fine powder of un-sintered polytetrafluoroethylene is uniformly mixed with a Uquid lubricant and then shaped into a product (sheet, rod or tube) by extrusion. After removal of the... 

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