A New Era in Porous Metals: Applications in Orthopaedics

Abstract

The development of porous metals and coatings has revolutionized the field of orthopaedics. However, most implants are fabricated utilizing traditional materials (i.e. sintered beads, fiber metal, plasma spray), which have several inherent limitations. Several new porous metals have been recently introduced to improve upon the biomaterial properties of these traditional metals. Tritanium (Stryker, Mahwah, NJ), Regenerex (Biomet, Warsaw, IN), Stiktite (Smith and Nephew, Memphis, TN), and Trabecular Metal (Zimmer, Warsaw, IN) are currently available for use in orthopaedic surgery, all with a characteristic appearance similar to cancellous bone. The open‐cell structure of these materials affords several intriguing properties, including; high volumetric porosity (60–80 %), low modulus of elasticity, and high frictional characteristics. The following represents a review of the biomaterial properties and applications in orthopaedic surgery for this new class of highly porous metals.

Porous magnesium-based scaffolds for tissue engineering

“…Accordingly, these materials are called open-cell porous metals, metallic foams, metallic scaffolds, or cellular metals with three-dimensional interconnected pores. The pore sizes are typically between 200 and 500 µm with total porosity of 50-75% [5].…”

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…Recent studies revealed an even greater biomedical potential for porous metals. [191][192][193][194] Metallic implants provide the necessary strength and toughness required in load-bearing parts of the body, and, due to these advantages, metals will continue to play an important role as orthopedic biomaterials in the future, even though there are concerns with regard to the release of certain ions from and corrosion products of metallic implants. Of course, neither metals nor alloys are biomimetic (the term biomimetic can be defined as a processing technique that either mimics or inspires the biological mechanism, in part or whole 195 ) in terms of chemical composition, because there are no elemental metals in the human body.…”

Physical and Biological Characterization of Ferromagnetic Fiber Networks: Effect of Fibrin Deposition on Short-Term In Vitro Responses of Human Osteoblasts

“…For example, RegenerexÔ (Biomet), which is a titanium coating, has a stiffness of *1.6 GPa with 67% porosity 50,51 whereas Trabecular MetalÔ (Zimmer), which is made of porous tantalum, has a Young's modulus of *3 GPa with porosity of 75-85%. 50,52 In the case of the fiber networks, it is important to note that the stiffness of the fiber material, the fiber volume fraction, the fiber orientation distribution, and the fiber segment aspect ratio are relevant to the magnitude of the Young's modulus values. For instance, the through-thickness Young's modulus of these networks is expected to be significantly lower due to the fact the fibers are lying in-plane and therefore would offer very low resistance to vertical displacement.…”