Poster Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

A case of multiple atypical femoral and non-femoral fractures after 10 years of oral bisphosphonates (#408)

Sylvia Ye 1 , Landy Wu 1 , Ie-Wen Sim 1 2 , Christopher Gilfillan 1
  1. Endocrinology, Eastern Health, Box Hill, Victoria, Australia
  2. Endocrinology, Monash Health, Melbourne, Victoria, Australia

Atypical femoral fractures (AFF) are rare1, and are associated with antiresorptive medications, ethnicity and glucocorticoids1,2, although exact mechanisms are unknown. Atypical fractures of non-femoral sites have recently been described.3

We present the case of a 69-year-old Caucasian female with multiple atypical non-healing fractures after 10 years of alendronate. There was no personal or family history of early fractures or osteoporosis, hearing or dental issues, or developmental delay. Alendronate was commenced after a non-osteoporotic ankle fracture at 49-years-old. Ten years later, she presented with a low trauma AFF (Figure 1). Post intramedullary nail fixation of the left femur, an asymptomatic contralateral femoral stress fracture was identified and received prophylactic nail fixation.

Dual-energy X-ray absorptiometry (DXA) showed normal T scores (Table 1), grossly unchanged from a baseline DXA 8 years prior, whilst secondary osteoporosis screen was unremarkable. Alendronate was ceased and bone turnover markers one year post cessation were unsuppressed (Table 1).

The left AFF was non-healing at 2 years despite multiple surgical revisions. The patient was treated with 18 months of teriparatide. Despite ongoing non-union and pain in the left femur, she was fracture-free for 7 years with stable bone densitometry and bone turnover markers. She then sustained an atraumatic right clavicle and low trauma right ulnar fracture, both with atypical features (Figure 1). She has been recommenced on teriparatide, referred for genetic testing and bone biopsy for histomorphometry.

Bisphosphonates are effective osteoporosis treatment but is associated with increased risk of AFF1, likely by suppressing remodelling, with bone histomorphometry often showing reduced bone turnover4. We hypothesise suppressed bone turnover in our patient due to inappropriate administration of bisphosphonates, leading to bilateral AFFs, atypical clavicular and atypical ulnar fractures. Genetic testing can exclude associated monogenetic bone disorders (e.g., pycnodysostosis, osteopetrosis)4 and may provide further insights into genetic susceptibility4 and underlying pathophysiology.

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  1. 1. Shane E, Burr D, Abrahamsen B, et al. Atypical subtrochanteric and diaphyseal femoral fractures: second report of a task force of the American Society for Bone and Mineral Research. J Bone Miner Res. 2014;29(1):1-23.
  2. 2. Black DM, Geiger EJ, Eastell R, et al. Atypical Femur Fracture Risk versus Fragility Fracture Prevention with Bisphosphonates. N Engl J Med. 2020;383(8):743-53.
  3. 3. Abe K, Kimura H, Yamamoto N, et al. Treatment strategy for atypical ulnar fracture due to severely suppressed bone turnover caused by long-term bisphosphonate therapy: a case report and literature review. BMC Musculoskelet Disord. 2020;21(1):802.
  4. 4. Nguyen HH, van de Laarschot DM, Verkerk A, Milat F, Zillikens MC, Ebeling PR. Genetic risk factors for atypical femoral fractures (AFFs): A systematic review. JBMR Plus. 2018;2(1):1-11.