Different surgical outcomes in a patient with bilateral atypical femoral fracture related to bisphosphonate use with or without teriparatide treatment.

Bisphosphonates (BPs) are first-line drugs for the treatment of osteoporotic fractures, but long-term use of BP reduces bone turnover and is associated with atypical femur fractures (AFFs). Additionally, BP treatment may cause delayed fracture healing or nonunion, which makes AFF treatment difficult. The incidence of AFF is generally low. In fact, there are only a few clinical reports of AFF and there is no controlled study on AFF treatment. Herein, we report a case of multiple osteoporotic fractures. After 5 years of BP treatment, left and right AFFs occurred within 2 years. The fracture types and surgical operations were the same, but the level of bone metabolism and drug treatment were different. The right AFF healed well following teriparatide initiation compared with non-healed left AFF with BP continuation; thus, our case can be considered a self-controlled study. Furthermore, we have reviewed the diagnosis and treatment of this case in detail and analyzed and investigated the potential causes of the different outcomes of AFFs between the two sides to inform the clinical treatment of atypical fractures. Mini Abstract We report a case of bilateral AFFs. The surgical treatments were the same, but the final treatment outcomes were different with or without teriparatide treatment. We investigated the potential causes of the different outcomes of AFFs between the two sides to inform the clinical treatment of AFFs.