Analysis of a Clinically Failed, Mechanically Intact, Hemi-Toe Implant

In this case study a clinically failed, mechanically intact, hemi-toe device was investigated. The clinical indication of the failure constitutes radiolucent line indicating loosening of the implant and possible interactions among the bone-implant initiated by osteolysis may become a factor, producing pain, inflammatory reactions, deformity and discomfort. The patient file was not available to determine these parameters. The device was titanium coated, Cobalt Chromium alloy used for making hemi-toe. Degeneration of hemi implant was due to spalling of the coating from the surface, causing loosening of stem from bone. However, pre-removal X-ray films were not available to confirm. Mechanism by which the clinical failure occurred likely due to lack of bony adhesion or other clinical reasons. Surface topographical features were documented using optical microscope. A method to classify various area of the articulating surface was proposed in this study that shows the anterior contacts were more damaging than the other areas where deeper scratches, pits and some debris were present. There is a need to converge mechanical and clinical failures together for these types of medical devices.