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Dhanekula ND, Crouch G, Byth K, Lau SL, Kim A, Graham E, Ellis A, Clifton‐Bligh RJ, Girgis CM. Asian Ethnicity and Femoral Geometry in Atypical Femur Fractures: Independent or inter‐dependent risk factors? JBMR Plus 2022; 6:e10607. [PMID: 35434447 PMCID: PMC9009102 DOI: 10.1002/jbm4.10607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 11/11/2022] Open
Abstract
The earliest reports of atypical femur fractures (AFF) emerged from Asia. In the West, epidemiologic studies report a greater incidence of AFFs among subjects of Asian background. Asian ethnicity is an established risk factor for AFF, but clear mechanisms to explain this risk and implications for the general development of AFF are open questions. Ethno‐specific differences in bisphosphonate action and femoral geometry have been proposed as hypotheses. In a retrospective cohort of 163 female patients presenting with AFFs or typical femur fractures (TFF), relative contributions of Asian ethnicity, proximal femoral geometry, and bisphosphonate use in AFF status were examined. There was a fourfold higher proportion of Asian subjects in the AFF compared with TFF groups (31.6%, 30/95 versus 7.4%, 5/68). Asian subjects had smaller femurs in femoral head, neck, and axial dimensions. A multiple logistic regression model for AFF status was fitted adding Asian ethnicity to three previously reported independent predictors of AFF including femoral geometry, which together comprise the Sydney AFF Score (age ≤80 years, femoral neck width <37 mm than non‐Asian, lateral cortical width at lesser trochanter ≥5 mm). Asian ethnicity was a robust independent predictor of AFF, imparting sevenfold increase in the odds of AFF after adjusting for all three variables (95% confidence interval [CI] 2.2–23.2, p = 0.001) or for overall AFF score (95% CI 2.2–22.3 p = 0.001). Overall Asian subjects had higher rates of bisphosphonate use than non‐Asian subjects (67.6% versus 47.2%, p = 0.034). Among AFF bisphosphonate users, Asian subjects had lower AFF scores than non‐Asians (Sydney AFF Score ≤1, 45.5% Asian subjects versus 22.2% non‐Asian subjects, p = 0.05). Asian ethnicity is a strong independent risk factor for AFF, unaccounted for by ethno‐specific differences in proximal femoral geometry. Bisphosphonate use may be associated with a greater predisposition for AFF in Asian subjects compared with non‐Asian subjects. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Nitesh D Dhanekula
- Faculty of Medicine and Health University of Sydney Sydney NSW Australia
- Department of Orthopaedic Surgery Westmead Hospital Westmead NSW Australia
| | - Gareth Crouch
- Faculty of Medicine and Health University of Sydney Sydney NSW Australia
| | - Karen Byth
- Faculty of Medicine and Health University of Sydney Sydney NSW Australia
- Western Sydney Local Health District (WSLHD) Research and Education Network, Westmead Hospital Westmead NSW Australia
| | - Sue Lynn Lau
- Faculty of Medicine and Health University of Sydney Sydney NSW Australia
- Department of Diabetes and Endocrinology Westmead Hospital Westmead NSW Australia
| | - Albert Kim
- Faculty of Medicine and Health University of Sydney Sydney NSW Australia
- Department of Diabetes and Endocrinology Westmead Hospital Westmead NSW Australia
- Department of Endocrinology and Diabetes Royal North Shore Hospital St Leonards NSW Australia
| | - Edward Graham
- Department of Orthopaedic Surgery Westmead Hospital Westmead NSW Australia
| | - Andrew Ellis
- Department of Orthopaedic Surgery Royal North Shore Hospital St Leonards NSW Australia
| | - Roderick J Clifton‐Bligh
- Faculty of Medicine and Health University of Sydney Sydney NSW Australia
- Department of Endocrinology and Diabetes Royal North Shore Hospital St Leonards NSW Australia
- Kolling Institute of Medical Research Sydney NSW Australia
| | - Christian M Girgis
- Faculty of Medicine and Health University of Sydney Sydney NSW Australia
- Department of Diabetes and Endocrinology Westmead Hospital Westmead NSW Australia
- Department of Endocrinology and Diabetes Royal North Shore Hospital St Leonards NSW Australia
- The Westmead Institute for Medical Research Westmead NSW Australia
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Crouch G, Dhanekula ND, Byth K, Burn E, Lau SL, Nairn L, Nery L, Doyle J, Graham E, Ellis A, Clifton-Bligh RJ, Girgis CM. The Sydney AFF Score: A Simple Tool to Distinguish Females Presenting With Atypical Femur Fractures Versus Typical Femur Fractures. J Bone Miner Res 2021; 36:910-920. [PMID: 33528853 DOI: 10.1002/jbmr.4255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 01/05/2021] [Accepted: 01/12/2021] [Indexed: 01/21/2023]
Abstract
Atypical femur fractures (AFF) are a rare but serious complication of long-term bisphosphonate use. Although clearly defined by ASBMR criteria, a proportion of patients with AFFs may go unrecognized and the use of qualitative fracture criteria may lead to uncertainty in AFF diagnosis, with significant therapeutic implications. A score that rapidly and accurately identifies AFFs among subtrochanteric femur fractures using quantitative, measurable parameters is needed. In a retrospective cohort of 110 female patients presenting with AFFs or typical femur fractures (TFFs), multiple logistic regression and decision tree analysis were used to develop the Sydney AFF score. This score, based on demographic and femoral geometry variables, uses three dichotomized independent predictors and adds one point for each: (age ≤80 years) + (femoral neck width <37 mm) + (lateral cortical width at lesser trochanter ≥5 mm), (score, 0 to 3). In an independent validation set of 53 female patients at a different centre in Sydney, a score ≥2 demonstrated 73.3% sensitivity and 69.6% specificity for AFF (area under the receiver-operating characteristic curve [AUC] 0.775, SE 0.063) and remained independently associated with AFF after adjustment for bisphosphonate use. The Sydney AFF score provides a quantitative means of flagging female patients with atraumatic femur fractures who have sustained an AFF as opposed to a TFF. This distinction has clear management implications and may augment current ASBMR diagnostic criteria. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Gareth Crouch
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Nitesh D Dhanekula
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.,Department of Orthopaedic Surgery, Westmead Hospital, Westmead, NSW, Australia
| | - Karen Byth
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.,Western Sydney Local Health District (WSLHD) Research and Education Network, Westmead Hospital, Westmead, NSW, Australia
| | - Emma Burn
- Department of Medicine, West Suffolk Hospital, Bury St Edmonds, UK
| | - Sue Lynn Lau
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.,Department of Endocrinology and Diabetes, Westmead Hospital, Westmead, NSW, Australia
| | - Lillias Nairn
- Department of Physiotherapy, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Liza Nery
- Department of Endocrinology and Diabetes, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Jean Doyle
- Department of Endocrinology and Diabetes, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Edward Graham
- Department of Orthopaedic Surgery, Westmead Hospital, Westmead, NSW, Australia
| | - Andrew Ellis
- Department of Orthopaedic Surgery, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Roderick J Clifton-Bligh
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.,Department of Endocrinology and Diabetes, Royal North Shore Hospital, St Leonards, NSW, Australia.,Kolling Institute of Medical Research, Sydney, NSW, Australia
| | - Christian M Girgis
- Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.,Department of Endocrinology and Diabetes, Westmead Hospital, Westmead, NSW, Australia.,Department of Endocrinology and Diabetes, Royal North Shore Hospital, St Leonards, NSW, Australia.,The Westmead Institute for Medical Research, Westmead, NSW, Australia
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