As concerns over the possible effects of metal-on-metal implants continue to percolate and the pressure for fewer revisions intensifies, orthopaedic device manufacturers are taking a longer look at alternative materials. From emerging biomaterials to tried-and-true fabrics, fiber-based structures have the potential to satisfy the functional capabilities that device applications require by delivering more biomimetic performance than ever before. A long and steady evolution of more natural structures made from fiber has now extended to pieces as integral as ligaments and tendons.
Biomedical textile structures better mimic the natural makeup of tissue, and thus offer more lifelike movement and overall performance than metals, alloys, ceramics and other traditional materials. Among biomaterials specifically, biomedical textiles are unique due to their ability to be at once lightweight, porous, conformable and strong. And because these attributes enable better mobility and flexibility, they also significantly increase the possibility of an improved—and quicker—patient healing process.
Absorbability Enables Real Tissue Growth
For several years, the orthopaedic industry has been steadily increasing its use of Ultra High Molecular Weight Polyethylene (UHMWPE) due to its high strength and ability to meet durability requirements after implantation. What OEMs need now, however, are longer-term absorbable options that can provide the same level of strength for support while offering dual regrowth capabilities for natural cells. Enabling absorbability without sacrificing strength is a best-case scenario for many applications, but has only recently been explored as a viable alternative to the traditionally strong but permanent implants in many parts of the body.
Many orthopaedic devices aid in support and reconstruction at the same time, so absorbable fibers must be able to induce the regrowth of natural tissue as they perform repair functions. The lifelike properties of textile structures allow for post-operative mobility while enabling cellular regeneration, but only under precise mechanical specifications and a carefully engineered degradation profile. For absorbable structures, implantation as repair allows the textile to act in place of the damaged tissue even as it encourages cell growth. As new cells multiply, the textile steadily degrades and is replaced by completely natural tissue, but its load-bearing capabilities are critical to both early mobility post-implant and natural healing before this tissue growth is complete.
Until now, the most common understanding of absorbable textiles was an acknowledgement of their value in tissue engineering applications in areas outside orthopaedic construction where strength is often less important.
Textile structures intended to bear a load while still functioning dynamically now include braided textiles and tapered weaves, both two- and three-dimensional. Composed of long-term absorbable fibers such as PGA, PLLA, PDO or other biomaterials, they have unique properties according to their processing.