Early aseptic loosening of a porous tantalum knee prosthesis.

Porous tantalum represents a relatively new solution for primary and revision total knee arthroplasty, offering several unmatched properties. Tantalum is a transition metal, with excellent biocompatibility and bioactivity due to its intrinsic physical and structural characteristics. A widespread clinical use of porous tantalum tibial components for primary total knee arthroplasty has been partly hindered by the difficulty in removing this type of implant after bone in growth, often leading to a significant bone defect. On the contrary, in the case here reported, removal of the trabecular metal tibial component was unexpectedly easy at a 7-month follow-up due to the absence of bone ingrowth but with a complete preservation of the tibial plate bone stock. Causes for the lack of bone ingrowth are discussed.