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Re: Absence of femoral cortical thickening in long-term bisphosphonate users: Implications for atypical femur fractures
Bone 68 (2014) 165
Contents lists available at ScienceDirect
Bone journal homepage: www.elsevier.com/locate/bone
Letter to the Editor Re: Absence of femoral cortical thickening in long-term bisphosphonate users: Implications for atypical femur fractures☆
Dear Editor, We read with interest the study of Chen F and his colleague [1], and wish to congratulate the authors on work which adds to our knowledge and understanding of the difficult clinical problem of atypical femur fractures. However, we have some concerns regarding the paper and wish to share them. As we know, bisphosphonates reduce bone remodeling, which may “freeze” the skeleton, allowing accumulation of microcracks over time, leading to fatigue fractures (also called stress fractures or atypical fracture) [2]. Such fractures are well known in mechanical engineering, and they occur with age and with low incidence in the clinical, which is ranging from 3.2 to 50 cases per 100,000 person-years [3]. So the relatively elderly age and enough sample size are prerequisite for study on atypical femur fractures [4,5]. Most of the previous studies were composed of elderly patients and enough sample size. For example, Schilcher J's study [4] published in the New England Journal of Medicine in 2011 found that there were 59 atypical fractures in all the 12,777 patients. All the 59 patients had an averaged age of nearly 75 years old. Elderly patients often have a variety of medical comorbidities, such as hypertension, diabetes, chronic obstructive pulmonary disease and so on. The complicated medical comorbidities usually need many drug treatment, which make their metabolic process of associated osteoporosis more complex, and more prone to atypical femoral fractures. It means that atypical femoral fractures are the results of complex metabolic abnormalities, and elderly age and other conditions of metabolic abnormalities have greater chance to induce such fracture. For example, Chang ST has done an interesting study on observation of a total of 62 patients with breast cancer (N = 39) or multiple myeloma (N = 23) treated with intravenous bisphosphonates, and found that six cases (4 breast cancer, 2 multiple myeloma) occurred atypical femur fracture [6]. However, in the study of Chen F and colleague [1], the age of the patients was relatively young in nearly all the published analogous English
☆ The authors confirm that there are no known conflicts of interest associated with this publication and that there has been no significant financial support for this work that could have influenced its outcome.
http://dx.doi.org/10.1016/j.bone.2014.06.024 8756-3282/© 2014 Elsevier Inc. All rights reserved.
literature and lack comparison of medical comorbidities by the Charlson comorbidity index score or other tools, although the authors' study was powered at the 95% level to detect a 10% difference in cortical thickness ratio. However, the atypical was a rare disease with incidence of only 3.2 to 50 cases per 100,000 person-years. Therefore, in this case of only 43 patients, the author should use the most sensitive imaging modality such as MRI to identify more occult fractures. Because the occult atypical femoral fractures occur in relatively young patients it can heal slowly with minor external bone formation, often appearing as slightly cortical thickening [7].
References [1] Chen F, Wang Z, Bhattacharyya T. Absence of femoral cortical thickening in long-term bisphosphonate users: implications for atypical femur fractures. Bone 2014;62:64–6. [2] Neer RM. Skeletal safety of tiludronate. Bone 1995;17(Suppl.):501S–3S. [3] Shane E, Burr D, Abrahamsen B, Adler RA, Brown TD, Cheung AM, 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. [4] Schilcher J, Michaëlsson K, Aspenberg P. Bisphosphonate use and atypical fractures of the femoral shaft. N Engl J Med 2011;364(18):1728–37. [5] Lenart BA, Neviaser AS, Lyman S, Chang CC, Edobor-Osula F, Steele B, et al. Association of low-energy femoral fractures with prolonged bisphosphonate use: a case control study. Osteoporos Int 2009;20(8):1353–62. [6] Chang ST, Tenforde AS, Grimsrud CD, O'Ryan FS, Gonzalez JR, Baer DM, et al. Atypical femur fractures among breast cancer and multiple myeloma patients receiving intravenous bisphosphonate therapy. Bone 2012;51(3):524–7. [7] Eriksen EF, Díez-Pérez A, Boonen S. Update on long-term treatment with bisphosphonates for postmenopausal osteoporosis: a systematic review. Bone 2014;58:126–35.
Yueju Liu⁎ Yingze Zhang Third Hospital of Hebei Medical University, Shijiazhuang 050051, PR China Key Orthopaedic Biomechanics Laboratory of Hebei Province, Shijiazhuang, PR China ⁎Corresponding author at: Department of Orthopedic Center, Third Hospital of Hebei Medical University, No. 139 Zi Qiang Road, Shijiazhuang, Hebei 050051, PR China. Fax: +86 311 8702 3626. 16 May 2014
Contents lists available at ScienceDirect
Bone journal homepage: www.elsevier.com/locate/bone
Letter to the Editor Re: Absence of femoral cortical thickening in long-term bisphosphonate users: Implications for atypical femur fractures☆
Dear Editor, We read with interest the study of Chen F and his colleague [1], and wish to congratulate the authors on work which adds to our knowledge and understanding of the difficult clinical problem of atypical femur fractures. However, we have some concerns regarding the paper and wish to share them. As we know, bisphosphonates reduce bone remodeling, which may “freeze” the skeleton, allowing accumulation of microcracks over time, leading to fatigue fractures (also called stress fractures or atypical fracture) [2]. Such fractures are well known in mechanical engineering, and they occur with age and with low incidence in the clinical, which is ranging from 3.2 to 50 cases per 100,000 person-years [3]. So the relatively elderly age and enough sample size are prerequisite for study on atypical femur fractures [4,5]. Most of the previous studies were composed of elderly patients and enough sample size. For example, Schilcher J's study [4] published in the New England Journal of Medicine in 2011 found that there were 59 atypical fractures in all the 12,777 patients. All the 59 patients had an averaged age of nearly 75 years old. Elderly patients often have a variety of medical comorbidities, such as hypertension, diabetes, chronic obstructive pulmonary disease and so on. The complicated medical comorbidities usually need many drug treatment, which make their metabolic process of associated osteoporosis more complex, and more prone to atypical femoral fractures. It means that atypical femoral fractures are the results of complex metabolic abnormalities, and elderly age and other conditions of metabolic abnormalities have greater chance to induce such fracture. For example, Chang ST has done an interesting study on observation of a total of 62 patients with breast cancer (N = 39) or multiple myeloma (N = 23) treated with intravenous bisphosphonates, and found that six cases (4 breast cancer, 2 multiple myeloma) occurred atypical femur fracture [6]. However, in the study of Chen F and colleague [1], the age of the patients was relatively young in nearly all the published analogous English
☆ The authors confirm that there are no known conflicts of interest associated with this publication and that there has been no significant financial support for this work that could have influenced its outcome.
http://dx.doi.org/10.1016/j.bone.2014.06.024 8756-3282/© 2014 Elsevier Inc. All rights reserved.
literature and lack comparison of medical comorbidities by the Charlson comorbidity index score or other tools, although the authors' study was powered at the 95% level to detect a 10% difference in cortical thickness ratio. However, the atypical was a rare disease with incidence of only 3.2 to 50 cases per 100,000 person-years. Therefore, in this case of only 43 patients, the author should use the most sensitive imaging modality such as MRI to identify more occult fractures. Because the occult atypical femoral fractures occur in relatively young patients it can heal slowly with minor external bone formation, often appearing as slightly cortical thickening [7].
References [1] Chen F, Wang Z, Bhattacharyya T. Absence of femoral cortical thickening in long-term bisphosphonate users: implications for atypical femur fractures. Bone 2014;62:64–6. [2] Neer RM. Skeletal safety of tiludronate. Bone 1995;17(Suppl.):501S–3S. [3] Shane E, Burr D, Abrahamsen B, Adler RA, Brown TD, Cheung AM, 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. [4] Schilcher J, Michaëlsson K, Aspenberg P. Bisphosphonate use and atypical fractures of the femoral shaft. N Engl J Med 2011;364(18):1728–37. [5] Lenart BA, Neviaser AS, Lyman S, Chang CC, Edobor-Osula F, Steele B, et al. Association of low-energy femoral fractures with prolonged bisphosphonate use: a case control study. Osteoporos Int 2009;20(8):1353–62. [6] Chang ST, Tenforde AS, Grimsrud CD, O'Ryan FS, Gonzalez JR, Baer DM, et al. Atypical femur fractures among breast cancer and multiple myeloma patients receiving intravenous bisphosphonate therapy. Bone 2012;51(3):524–7. [7] Eriksen EF, Díez-Pérez A, Boonen S. Update on long-term treatment with bisphosphonates for postmenopausal osteoporosis: a systematic review. Bone 2014;58:126–35.
Yueju Liu⁎ Yingze Zhang Third Hospital of Hebei Medical University, Shijiazhuang 050051, PR China Key Orthopaedic Biomechanics Laboratory of Hebei Province, Shijiazhuang, PR China ⁎Corresponding author at: Department of Orthopedic Center, Third Hospital of Hebei Medical University, No. 139 Zi Qiang Road, Shijiazhuang, Hebei 050051, PR China. Fax: +86 311 8702 3626. 16 May 2014