Revision strategy after metal on metal THR failure: Conversion to ceramic on ceramic

Abstract

The new technology of ceramic heads with titanium alloy adapter sleeves allows to consider new developments for the use of ceramic-ceramic wear couples in T.H.A. revisions .One of the main topics is now the revision of second generation metal on metal T.H.A. The authors report their early experience and the new perspectives for other revision procedures. Six patients have been revised using this technique. Five cemented Weber cups were removed due to dysfunction of the Metasul wear couple; the socket was not loose but worrying osteolysis and local radiolucencies were observed. The serum metal ion levels were significantly increased One of those cases was already a failed revision (a previous Metasul T.H.A. revised using again a Metasul friction couple with the same local problems). In all of those cases, the anodised titanium femoral stem was cemented; no loosening of the implants could be observed. The last case was a Durom wear couple with a cementless cup and a well fixed titanium Zweymuller stem. This revision was due to an anterior impingement between the big metallic femoral head and the ilio-psoas muscle. The cup fixation was doubtful. For all of those stems, the characteristics of the 12/14 Titanium alloy taper trunnions were checked to assess the compatibility with the Ceramtec sleeves. The procedure was the same in all cases; the revision was performed using the previous approach (anterior approach) in a lateral decubitus for the first five cemented cases and posterior approach for the Durom implant. The Titanium alloy taper was carefully preserved and inspected to detect delerious lesions excluding the indication for a conservative procedure using delta alumina femoral heads. In no case, we observed corrosion or macroscopic lesions of the titanium alloy taper trunnions. We encountered 3 severe macroscopic metallosis cases due to the chromium cobalt alloy of the friction surfaces with a good correlation with serum samples tests. The acetabular cups were removed and cementless Ceramconcept cups were implanted using classical XLW delta alumina inserts. The 32mm delta alumina heads were adjusted on the femoral stems using the precise technique for impaction of the titanium alloy adapter sleeves. We did not face any problem at this stage. We did not notice any parasitic impingement due to the additional sleeve. To date, we did not observe any complications. The CT scan scout view has been used to check radiographically the sleeve assembly in those first cases. During the follow-up, we observed the progressive normalization of the metal serum levels.