THE PROCESS OF POROUS TANTALUM IMPLANTS OSSEOUS INTEGRATION A REVIEW

Porous tantalum is a biomaterial that was recently introduced in orthopaedics in order to overcome problems of the past related to implant loosening. Its use has led to very good results, especially in difficult cases where severe bone defect is present, as it is found to have osteoconductive and possibly, osteoinductive properties. So, it is of great inter est to shed light to the mechanisms through which t his material leads to new bone formation after being im planted. For this reason, a review of the current literature was undertook. Porous tantalum is, biolo gically, relatively inert, meaning that its bonding capacity to the bone is restricted. In order to overcome this o bstacle, it undergoes thermal processing in alkalin e environment. This process leads to extensive hydroxyapatite form ation on its surface and thus, to better integratio n of porous tantalum implants. Apart from this, new bone tissue formation occurs inside the pores of porous tantal um after its implantation and this new bone retains the characte ristics of normal bone, i.e., bone remodeling and H aversian systems formation. This finding is enhanced by the observation that porous tantalum is an appropriate substrate for osteoblast adherence, proliferation and differe ntiation. Furthermore, the finding that osteoblasts derived from old women (>60 years old) and cultivated on porous tantalum may grow faster than osteoblasts taken fro m younger women (<45 years old) and cultivated on other substrates, can partially explain porous tantalu m good performance in cases of patients with severe bone d efects. In conclusion, porous tantalum chemical and mechanical properties are those that, probably, def ine the already noticed good performance of this ma terial. However, further research is needed to totally clar ify the mechanisms through which they contribute to that.