PTFE Sutures

A backbone sheathed in fluorine

PTFE is a fluoropolymer — the polymer of tetrafluoroethylene, in which every hydrogen that would sit on an ordinary hydrocarbon chain has been replaced by fluorine. What that leaves is a carbon backbone completely enclosed in a sheath of fluorine atoms, held by carbon–fluorine bonds that are short, strong and stable. That structure is the origin of the word most often attached to the material: inert.

It is worth being precise about what inert means here, because it is a chemical statement and it is easy to read as a clinical one. It says the polymer does not readily enter into reactions. There is no ester bond in the chain for water to attack, no amide or peptide bond for a tissue enzyme to recognise, and the fluorine shell leaves little of the backbone exposed to anything that might. It does not, on its own, say how a particular product behaves in a particular tissue over time. That is a separate question, and it is answered by the instructions for use supplied with the product.

Monofilament construction, and what follows from it

PTFE suture is extruded as a monofilament — one continuous strand, rather than many fine filaments braided together. Several of the properties usually listed for the material are consequences of that construction rather than of the chemistry.

There are no interstices, because there are no separate filaments to leave spaces between. With no interstices there is no capillarity: no route along which fluid can wick the length of the strand. Capillarity belongs to braided construction, and a monofilament does not have it.

The same reasoning explains the absence of a coating. A coating on a suture is an answer to a problem braiding creates — the surface texture a braid carries, and the interstices between its filaments. A monofilament presents neither, so there is nothing for a coating to address. PTFE suture is supplied undyed, from 100% high-density polymer, with no additives.

dPTFE and ePTFE: one polymer, two physical forms

The abbreviations are the most confusing thing about this material, and they do not describe different chemistries. PTFE names the polymer. What follows the letter in front of it names what was done to that polymer after it was made.

Expanded PTFE (ePTFE) is PTFE stretched under controlled conditions. The stretching opens the solid into a microporous structure of nodes joined by fine fibrils — chemically identical material, physically a different one, with pores where the dense form has none. That porosity is the defining feature of the form, and it is why ePTFE also appears in products that are not sutures at all.

Dense PTFE (dPTFE), sometimes written high-density PTFE, is the unexpanded form. It is not stretched, so the node-and-fibril structure never develops and the material stays effectively non-porous. A dense PTFE monofilament is therefore a solid strand rather than a microporous one — which is the form described throughout this article, and the form a 100% high-density PTFE suture is made of.

So the useful question about any PTFE product is not “is it PTFE” — both are — but which physical form, because porosity is the property that separates them:

The distinction matters mainly because the two names are close enough to be used loosely. They are separate materials with separate documentation, and what is stated about one — construction, porosity, approved indications — should not be read across to the other. Each product’s own instructions for use is the document that applies to it.

Where it sits among non-absorbable materials

Non-absorbable is a practical category rather than a chemical one, and it groups materials that differ considerably. Silk is a protein fibre held together by peptide bonds; polyamide has amide bonds along its chain. Both are classed non-absorbable, and both are nevertheless changed in tissue over time, because both carry a bond that can be hydrolysed. PTFE and polypropylene do not: one is a fluorinated carbon chain, the other a plain hydrocarbon chain, and neither offers water or an enzyme anything to cleave.

So the category describes the intent — a strand not designed to be broken down and resorbed — while the chemistry describes why, and the two are worth keeping apart when reading about any material in this group.

Dolphin Sutures supplies PTFE suture under the brand name Teflene, and was the first Indian brand to introduce a PTFE suture. What any individual product is approved for, and in which markets, is stated in its instructions for use.