Clinical validation of a structural porous tantalum biomaterial for adult reconstruction.

Various porous coatings—most notably, those manufactured by the sintering of cobalt-chrome or titanium beads and the diffusion bonding of titanium fiber wires—have been utilized for the biologic attachment of orthopaedic implants during the past three decades1. About ten years ago, a novel porous biomaterial made from commercially pure tantalum2-5 with a unique set of physical and mechanical properties was developed. Compared with conventional porous coatings, this material possesses higher volume porosity, more freely communicating pores, a higher coefficient of friction against bone, and a lower bulk stiffness (Fig. 1). In addition, the material is structural in that it has sufficient strength to enable the manufacture of implants without the need for a supportive solid metal substrate. Fig. 1 Top, Scanning electron micrograph illustrating the three-dimensional, open-pored structure of the porous tantalum biomaterial. The inset highlights the slight microtexture on the tantalum struts that results from the manufacturing process. Bottom, Monoblock cups manufactured by partial infiltration of polyethylene into the porous tantalum shell by direct compression-molding. Previous studies have characterized the physical and mechanical properties of porous tantalum6,7. Histologic analyses of the bone and fibrous ingrowth responses to various implants in animals have indicated a propensity for rapid infiltration of porous tantalum with healing tissue and relatively rapid rates of mechanical attachment8-14. Recent cell-culture studies have characterized the osteoblastic response to commercially pure tantalum, adding further confirmation to its long history as a biocompatible elemental metal2-5,15. Porous tantalum has been utilized for a wide variety of clinical applications since 1997, including joint replacement, reconstruction following tumor resection, the treatment of avascular necrosis of the femoral head, and spine fusion. The purpose of the present study was to document the clinical results obtained with porous …