Fracture of fully hydroxyapatite-coated titanium femoral stem of a total hip replacement--a report of 3 cases.

Copyright © Taylor & Francis 2004. ISSN 0001–6470. Printed in Sweden – all rights reserved. DOI 10.1080/00016470410004175 Fracture of the femoral stem of a total hip replacement has become an unusual but well recognised complication when using cement. Fracture of the femoral stem in an uncemented total hip replacement is rare, however. We report 3 cases of fracture of the femoral stem (2 of which were done in our hospital and 1 that was referred from outside) with a hydroxyapatite-coated prosthesis where the metal was fully covered by the hydroxyapatite coating. The femoral prosthesis used was the JRI (Joint Replacement Instrumentation Ltd. or Furlong THR, London, UK), made of wrought titanium alloy with the surface completely covered with vacuum plasma sprayed hydroxyapatite coating. This coating is of 96% purity, has a thickness of 150 microns and a bond strength of 60 Mpa. It is attached to a 50-micron thick porous titanium undercoating. The stem has 3 parts. The rectangular proximal third with a small fin to counteract rotation is placed in the trochanter area. Further distally, there is a cone section to create mechanical stability. The distal portion is cylindrical. The design allows the distal femur to be over-reamed by 2 mm.