THU434 A Case Of An Atypical Femur Fracture Managed Medically With Teriparatide

Disclosure: S.V. Rupani: None. A. Kotwal: None. L. Graeff-Armas: None. Atypical femur fractures (AFFs) are atraumatic or low-trauma femur fractures located in the sub-trochanteric region or femoral shaft. AFFs represent around 0.5% of all femur fractures. The increased use of bisphosphonates has led to a rise in the incidence of AFFs as it has emerged as a potential complication. While the mechanism of bisphosphonate-related AFFs has yet to be elucidated, one proposed mechanism is that bisphosphonates can cause over-suppression of bone turnover. If over-suppression is a contributing factor, then hypothetically, anabolic therapy can help heal existing fractures and prevent impending fractures by reversing over-suppression. Numerous animal models have demonstrated that parathyroid hormone and teriparatide enhance fracture healing. However, clinical trials and meta-analyses on the effects of teriparatide in fracture healing have been equivocal. There have been both retrospective and prospective studies, along with anecdotal reports demonstrating the benefits of teriparatide in healing in AFFs. However, there have been no randomized controlled trials assessing the efficacy of teriparatide in AFFs. Based on this limited evidence, the American Society for Bone and Mineral Research recommends considering teriparatide in patients who have failed conservative therapy. We present a case of an incomplete AFF in the setting of short-term bisphosphonate use that was managed with teriparatide in addition to conservative measures. Our patient presented with a complete right AFF treated surgically and an incomplete left AFF that we managed medically with teriparatide. Repeat left femur imaging six months after starting teriparatide therapy showed interval callus formation consistent with a healed fracture. Right femur imaging also showed a healing proximal femoral shaft fracture status post intramedullary fixation. She completed twenty-five months of teriparatide therapy and did not sustain any interval fractures. Repeat imaging one year after completion of teriparatide therapy continued to show a stable healed left AFF, along with a healed right AFF. She is currently more than two years post-completion of teriparatide and has remained fracture free. This case highlights the role that teriparatide may have as an option for medical management in incomplete AFFs and to accelerate healing in complete AFFs that have been managed surgically. Furthermore, with therapeutic options for osteoporosis management limited in the post-AFF setting, teriparatide helps increase bone mineral density and reduce future fracture risk. Randomized controlled trials are needed to draw definite conclusions on the efficacy of teriparatide in managing AFFs. However, this is difficult given the rare occurrence of AFFs. Therefore, case reports like ours offer insight into when teriparatide may be helpful in managing AFFs. Presentation: Thursday, June 15, 2023