Periprosthetic femoral re-fractures pathogenesis, classification, and surgical implications.

Periprosthetic femoral re-fractures (PFRFs) represent an emerging challenge for orthopaedic surgeons, since their incidence is growing in the last years, but very few experiences about their management have been currently published. The present study aims to (1) introduce, for the first time, an etiologic classification for PRFRs and (2) to provide surgical and pharmacological tips for the correct management of these injuries. Periprosthetic femoral re-fractures (PFRFs) could be classified into traumatic-PFRFs (T-PFRFs) and pathological-PFRFs (P-PFRFs). T-PFRFs, i.e. the "true" periprosthetic re-fractures, present as new fracture lines occurring proximally or distally to a previous periprosthetic fracture, that has correctly healed. They are generally unpredictable injuries but, in selected cases, it is possible to predict them by analyzing the construct used in the treatment of the previous periprosthetic fracture. P-PFRFs, on the other hand, define re-fractures occurring on a previous periprosthetic non-union or delayed union: the new fracture line appears in the same district of the old one. According to the etiologic factors influencing the P-PFRFs pathogenesis, it is possible to define re-fractures caused by mechanical failures, biological failures, septic failures and multifactorial failures, i.e., a combination of the previously mentioned concerns. A successful postoperative outcome, following the surgical management of PFRFs, requires the correct identification of all the underlying causes, which should be promptly and appropriately managed.