Poster Presentation ANZBMS-MEPSA-ANZORS 2022

Assessing the effect of Asian ethnicity on bone microarchitecture in patients with Atypical Femoral Fractures using 3D Dual X-Ray Absorptiometry (DXA) (#226)

Albert S Kim 1 2 3 , Gareth Crouch 4 , Nitesh D Dhanekula 4 , Jean Doyle 5 , Lillias Nairn 5 , Liza M Nery 5 , Andrew Ellis 6 , Roderick Clifton-Bligh 4 5 , Christian M Girgis 3 4 5
  1. Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
  2. St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia
  3. Department of Diabetes and Endocrinology, Westmead Hospital, Westmead, NSW, Australia
  4. Faculty of Medicine & Health, University of Sydney, NSW 2600, Australia
  5. Department of Endocrinology, Diabetes and Metabolism, Royal North Shore Hospital, St Leonards, NSW, Australia
  6. Department of Orthopedic and Trauma Surgery, Royal North Shore Hospital, St Leonards, NSW, Australia

Introduction: Atypical femoral fractures(AFF) represent a rare, devastating complication related to long-term antiresorptive therapy. Asian ethnicity is an established risk factor for AFF but the mechanism for this is unclear. We utilised a 3D-DXA software algorithm (3DSHAPER, GalgoMedical, Spain) to generate quantitative computed tomography (QCT)-like models from DXA projections to assess the bone microarchitecture.

Methods: Retrospective review of areal BMD and 3D-DXA assessment of trabecular and cortical parameters at the contralateral hip and femoral shaft in patients on long-term antiresorptive therapy (>5years) who sustained AFFs and the left hip of those who did not.

Results: A total 54 femoral models were obtained using the 3D DXA algorithm including 17 AFF patients and 37 non-AFF patients. 9 of 17 AFF patients was Asian determined by country of birth. There was no difference in mean age(72.6 vs 74.2yrs), anthropometry, or duration of antiresorptive use between AFF and non-AFF patients(11.1 vs 11.1yrs).

There were no significant differences in the areal BMD in the femoral neck, trochanter, shaft and total hip. Total bone mineral content (BMC) was lower in AFF patients (23.4 vs 25.7g,p<0.05). Asian ethnicity was associated with significantly lower total BMC (21.5 vs 25.6g,p<0.01) and shaft BMC (14.2 vs 17.0g, p<0.05) in AFF patients. This was despite equivalent volumetric BMD and cortical volume. There was also no difference in mean cortical thickness. However, non-Asian AFF patients had higher total integral (71.3 vs 63.6cm3, p<0.001) and trabecular volume (55.9 vs 49.5cm3, p<0.01) compared to Asian AFF patients.

Conclusion: Lower BMC despite equivalent volumetric BMD and cortical volume was observed in AFF patients compared to patients on a similar duration of antiresorptive agents who did not sustain AFFs. Asian AFF patients had significantly lower BMC and trabecular volume compared to non-Asian AFF patients. Lower bone mineralisation in Asian individuals may increase AFF risk.

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  1. Girgis CM, Sher D, Seibel MJ. Atypical Femoral Fractures and Bisphosphonate Use. N Engl J Med. 2010 May 13;362(19):1848–9.
  2. Dhanekula ND, Crouch G, Byth K, Lau SL, Kim A, Graham E, et al. Asian Ethnicity and Femoral Geometry in Atypical Femur Fractures: Independent or Interdependent Risk Factors? JBMR Plus. 2022;6(4):e10607.
  3. Humbert L, Martelli Y, Fonolla R, Steghofer M, Di Gregorio S, Malouf J, et al. 3D-DXA: Assessing the Femoral Shape, the Trabecular Macrostructure and the Cortex in 3D from DXA images. IEEE Trans Med Imaging. 2017;36(1):27–39.