Histological study of atraumatic periprosthetic fractures: does atypical periprosthetic fracture exist?

PURPOSE: Is it possible a correlation between some periprosthetic femoral fractures and atypical fractures? CASE: We present a case of a 77-year-old woman with atypical periprosthetic femoral fracture. The patient had a history of long-term bisphosphonate use. We performed an open reduction, a synthesis of the fracture and a histological exam. The patient stopped the bisphosphonate (BF) therapy. Three months later, before starting the teriparatide treatment, the patient had a re-fracture so we did a second osteosynthesis and began a teriparatide therapy. After six months, the radiography showed a bone healing at the fracture site. RESULT: The histological examination confirmed the diagnosis of atypical femoral fracture. CONCLUSION: At first, the fracture showed a delayed union which led to a new surgery, as often happens in BF-related atypical fractures. Appropriate treatment (BF suspension and teriparatide beginning) permitted fracture healing. The atypical characteristic of the fracture was confirmed by histological exam. Some periprosthetic femoral fractures in patients treated with BF, especially in long time therapies, should be suspected as atypical fractures and a specific medical treatment should be performed, as well as a correct surgical treatment.