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

Atypical femur fracture (AFF) occurs after a shorter duration of anti-resorptive therapy in Asians compared with non-Asians: a Transcontinental Atypical Femoral Fracture Consortium (TrAFFiC) study. (#125)

Lucy Collins 1 2 , Cat Shore-Lorenti 1 , Colin Chen 1 , Fran Milat 1 2 , Shoshana Sztal-Mazer 3 4 , Christian Girgis 5 6 7 , Aasis Unnanuntana 8 , Richard Dell 9 , Roderick Clifton-Bligh 5 7 , Peter R Ebeling 1 2 , Hanh Nguyen 1 2 10 11
  1. Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, Victoria
  2. Department of Endocrinology, Monash Health, Melbourne , Victoria
  3. Department of Endocrinology and Diabetes, Alfred Health, Melbourne, Victoria, Australia
  4. Department of Public Health and Preventative Medicine, Monash University, Melbourne, Victoria
  5. Department of Endocrinology, Royal North Shore Hospital, Sydney, New South Wales
  6. Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales
  7. Department of Endocrinology and Diabetes, Westmead Hospital, Sydney, New South Wales
  8. Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
  9. Department of Orthopaedics, Southern California Permanente Medical Group, California, United States of America
  10. Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
  11. Department of Medicine, The University of Melbourne, Melbourne, Victoria

Anti-resorptive drugs are effective osteoporosis therapies, but fear of AFFs, a rare side effect, has led to faltering treatment rates. TrAFFiC is an international AFF registry established to characterise clinical, radiographic, bone densitometric, microarchitectural and genetic profiles of AFF patients. We present the cohort’s baseline phenotypic data.

AFF cases, referred from Australian and Thailand study sites, were reviewed by an orthopaedic surgeon (RD) to confirm they fulfilled the updated ASBMR AFF definition. Patients completed questionnaires (demographics, comorbidities, medications, AFF details). Pathology, bone densitometric and femoral radiographs were collected. Blood samples were provided for biobanking, and a subgroup had HR-pQCT scans.

166 patients (243 AFFs) were recruited (Table 1). Age at first AFF was 72 (IQR 65-79) years. Majority were female (96%), independently ambulating before AFF (72%) and 62 (37%) were of Asian ethnicity. Five patients had a rare bone disease. Anti-resorptive therapy was recorded in 90%, and median duration preceding first AFF was 8 (IQR 5-12) years. In Asians with AFF, ≤ 5 years of anti-resorptive use preceding initial AFF was more common than non-Asians (42% vs 26%, p=0.033), and duration of use was shorter [7.5 (IQR 4-11) vs 9 (IQR 5-14) years, p=0.018]. Delayed AFF healing (>6 months) was more common in those who were treatment naïve, had used anti-resorptives for ≤ 5 years, and duration of use was shorter [6 (IQR 2-11) vs 9 (IQR 6-12) years] (all p<0.01). 12% of cases received teriparatide after AFF.

Phenotypic data from this large AFF registry suggests Asian ethnicity is associated with AFF following a shorter duration of anti-resorptive therapy compared with non-Asian peers. Shorter duration of therapy was more common in those with delayed AFF healing, suggesting bone-related factors, rather than treatment regimen, may contribute to healing. Bone microstructure, radiographic and genetic factors underlying these differences will be evaluated.

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