Morphological study of bone ingrowth in a high porous metal (TMT). A case series of human implants

Biomaterial porosity is considered one of most important proprieties required to obtain fixation of bone ingrowth and ongrowth in prostheses. Since 1998 in the USA and from 2001 in Europe a new highly porous biomaterial, Trabecular Metal Technology (TMT, ©Zimmer, USA) has been used in orthopaedic surgery. It is composed of approximately 99% tantalum and 1% vitreous carbon, by weight. Animal studies have shown that TMT supports rapid and extensive bone ingrowth. This porous metal offers several advantages over conventional materials as the high regular porosity that is considered one of most important properties in bone ingrowth and ongrowth and offers high biocompatibility and osteoconductivity, also. In bibliography there are studies that demonstrated the biomechanical properties of tantalum that are sufficient to withstand physiological load. In this study we evaluate the short-term morphological findings of TMT implanted in patients with osteonecrosis of a femoral head. Bone lamellae and cells with a lot of vascular structures are present. In particular the mineralization begin near on surface of tantalum lacunae. The bone penetrated the porous metal and many characteristics of good bio-integration were evident such as a vascularization inside the TMT, the formation of new bone, the absence of fracture and signs of implant metallosis. The presence of peri-implant medullary cisternae confirmed the functional sites of new bone formation.