Comment on: Modular titanium alloy neck failure in total hip replacement

To the Editor of the SICOT-J Orthopaedic Journal, I am writing to you as I would like to kindly express some considerations on the case-report of Dr. Marco Ceretti on ‘‘Modular titanium alloy neck failure in total hip replacement’’ published in your on-line journal last April (M. Ceretti and F. Falez SICOT J 2016, 2, 20). The Authors report on ‘‘a case of a repetitive modular femoral neck prosthesis fracture’’; they had initially revised a broken modular Metha stem with a MODULUS stem, neck 135 long, head 36 medium in a 43-year-old woman with body mass index (BMI) 38.6 kg/m (weight 110 kg, height 170 cm); both stems presented modular necks in titanium alloy. The MODULUS stem was then revised with a Wagner monoblock uncemented titanium stem following the fracture at the neckstem junction. This article reports a clinical case but it does not include any laboratory evidence in terms of fracture analysis to support the Authors’ conclusions and to elucidate the mechanisms of failure. No retrieval analysis on the two stems seems to have been in fact carried out, such as standard macroscopic inspection and observations, standard corrosion testing, micro analysis of the implant alloy, light microscopy, Scanning Electron Microscopy (SEM) and patient’s blood sample to check the release of metal ions. Besides, several publications nowadays report comparative analysis of cobalt-chromium and titanium modular femoral necks, showing that the first material present ‘‘improved resistance against fretting’’ with ‘‘lower incidence of surface micromotions’’ (e.g. [1, 2]). Nevertheless, the fracture of these two modular necks should be attributable to an error of indication and not to a failure of the devices themselves, meant to be used in patients with lower BMI. The surgical technique of the MODULUS stem reports: