Biomaterials 27 (2006) 4671–4681 Leading Opinion Experimental and clinical performance of porous tantalum in orthopedic surgery $ Brett Russell Levine a, , Scott Sporer a , Robert A. Poggie b , Craig J. Della Valle a , Joshua J. Jacobs a a Orthopaedics, Rush University Medical Center, 1725 E. Harrison Street, Suite 1063, Chicago, IL 60612, USA b Global Brand Management, Zimmer Trabecular Metal Technology, Inc., 10 Pomeroy Road, Parsippany, NJ 07054, USA Received 12 March 2006; accepted 28 April 2006 Abstract Porous tantalum, a new low modulus metal with a characteristic appearance similar to cancellous bone, is currently avai several orthopedic applications (hip and knee arthroplasty, spine surgery, and bone graft substitute). The open-cell structu dodecahedrons is produced via carbon vapor deposition/infiltration of commercially pure tantalum onto a vitreous carbon This transition metal maintains several interesting biomaterial properties, including: a high volumetric porosity (70–80%), of elasticity (3 MPa), and high frictional characteristics. Tantalum has excellent biocompatibility and is safe to use in vivo a its historicaland currentuse in pacemakerelectrodes, cranioplastyplatesand as radiopaquemarkers.The bioactivityand biocompatibility of porous tantalum stems from its ability to form a self-passivating surface oxide layer. This surface layer formation of a bone-like apatite coating in vivo and affords excellent bone and fibrous in-growth properties allowing for rap substantial bone and soft tissue attachment. Tantalum-chondrocyte composites have yielded successful early results in vitro and may afford an option for joint resurfacing in the future. The development of porous tantalum is in its early stages of evolution and th following represents a review of its biomaterial properties and applications in orthopedic surgery. r 2006 Elsevier Ltd. All rights reserved. Keywords: Tantalum; Orthopaedics 1. Introduction Conventional orthopedic implants have typically been fashioned from stainless steel, cobalt–chromium (CoCr), or titanium alloys.Numeroussurface coatings and porous designs have been developed to enhance biological fixation of these implants to bone for use in orthopedic procedures [1].Although excellent clinicalresultshave been shown with these materials, they have several inherent limitatio (low volumetric porosity, relativelyhigh modulus of elasticity and low frictional characteristics). To address the limitations of these solid metals, a new porous tantal biomaterialhas been developed(Zimmer, Trabecular Metal Technology, Inc., Parsippany, NJ). Porous tantalum is an open-cell tantalum structure of repeating dodecahedrons with an appearance similar to cancellous bone. The ability to alter the vitreous carbon skeleton of the metal allows for a near limitless scope in design,as evidenced by thewide variety of available orthopedic implants [2]. Tantalum isa transition metal (atomic number 73; atomic weight180.05)thatremains relatively inertin vivo. Dating back to the mid-1900s multiple medical devices have been fabricated that utilize thismaterial,including:pacemakerelectrodes, foil and mesh for nerve repair, radiopaque markers, and craniopla ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2006.04.041 $ Editor’s Note: Leading Opinions:This paper is one of a newly instituted series of scientific articles that provide evidence-based scientific opinions on topical and important issues in biomaterialsscience. They have some features of an invited editorial but are based on scientific facts,and some features of a review paper, withoutattempting to be comprehensive. These papers have been commissioned by the Editor-in- Chief and reviewed for factual, scientific content by referees. Corresponding author. Tel.: +1 630 243 4244; fax: +1 312 942 1517. E-mail addresses: brettlevinemd@gmail.com (B.R. Levine), bob.poggie@zimmer.com (R.A. Poggie), craigdv@yahoo.com (C.J. Della Valle), jacobs.jacobs@rushortho.com (J.J. Jacobs).