Tissue Reaction to Orthopaedic Implants, Case Presentation of Metal Allergie after Periprosthetic Ostheosintesis

Tissular reaction to orthopedic implants has been thoroughly studied, since it can be responsible for invalidating pain, as well as for implant loosening, thus requiring implant removal (which, otherwise, has no specific indications). The reaction is enhanced by certain characteristics of the host, such as age, comorbidities, as well as co-existence of different implants. We present the case of a patient who sustained a periprosthetic fracture (following total knee prosthesis) for which osteosynthsis with titanium plate and screws was performed. Early after surgery pain and swelling appeared, without any sign of infection; synovial proliferation with stable prosthesis was revealed during arthroscopy, but, due to resistant symptoms, arthrotomy was indicated. Fracture had healed, thus allowing plate removal, but, due to loosening, the prosthesis had to be extracted, too, with ExFix stabilisation on cement spacer. Favourable outcome after both implants were extracted proved that the implants were responsible for the pain and swelling, thus justifying the chosen treatment, although this resulted in a fix joint. The microscopical examination confirmed the tissular reaction producing the symptoms. Since each of the implants are hardly responsible for such reactions, we must presume that their association, dictated by the periprosthetic fracture, was the one who induced the rejection symptoms. It is currently unclear whether implant failure modifies the tissues surrounding the implant or if there are microscopically quantifiable alterations of the tissue before the implant fails, but in this case, the reaction generated by the interaction of the two implants can be considered responsible not only for the pain, but for the loosening of the prosthesis, too.