FIXATION AND METAL RELEASE FROM THE TIFIT FEMORAL STEM PROSTHESIS - 5-YEAR FOLLOW-UP OF 64 CASES

We stratified the fixation of the femoral component in 64 hips with de generative joint disease into 3 groups, cemented (C), proximal hydroxy apatite coating (HA) or proximal porous coating (P), All implants had the same basic design and were made of TiAlV alloy. The migration of t he implants was assessed by radiostereometry, After 5 years, the mean subsidences in the cemented and porous-coated groups were 0.16 and 0.3 1 mm, whereas the HA-coated implants displayed a mean proximal migrati on of 0.1 mm, 7 stems (2 C, 1 HA, 4 P) showed a continuous subsidence (> 0.25 mm) between the 2- and 5-year follow-up. 1 porous-coated stem was revised after the P-year follow-up, because of pain and implant fa ilure (previously reported) and 1 cemented stem was revised after 5 ye ars because of pain and osteolysis. In a subset of patients, all with a femoral head made of aluminum oxide, the levels of metal were determ ined using atomic adsorption spectrometry, Subsidence of the stem betw een the 2- and 5-year follow-up was associated with increased levels o f aluminum in the blood at 2 years. Generation of metallic particles f rom abrasive wear of the stem followed by third body abrasion of the c eramic femoral head could be one explanation of this finding. 5 hips w hich had shown high levels of titanium and aluminum in joint fluid at the 2-year follow-up displayed increased subsidence and developed prox imal radiolucencies or osteolysis at the 5-year follow up. One of thes e was the cemented hip which was subsequently revised.