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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 12  |  Issue : 1  |  Page : 92-94

Atypical stress femoral shaft fracture secondary to alendronate therapy


1 Medical Research, Francisco Marroquín University, Guatemala
2 Department of Traumatology and Orthopaedics, Centro Médico Hospital, Guatemala

Date of Submission14-Feb-2020
Date of Acceptance14-Apr-2020
Date of Web Publication26-Jun-2020

Correspondence Address:
Dr. Mario Cahueque
6a Ave., 7-39 Zona 10 Edificio las Brisas 4to Nivel, Guatemala
Guatemala
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jotr.jotr_11_20

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  Abstract 


Bisphosphonate (BP) therapy is widely used as it remains the first-line of treatment for osteoporosis. These antiresorptive drugs inhibit osteoclast function and promote apoptosis. However, atypical stress femoral fractures occurring in the diaphysis and subtrochanteric region are linked to prolonged BP use. The risk of fracture is directly proportional to the time exposed to the treatment. Ongoing BP exposure prevents bone resorption and replacement in areas with accumulated microdamage through targeted remodeling. Therefore, long-term BP use (more than 5 years) is an important risk factor. Atypical femoral fractures remain very rare, and the benefits of BP therapy for osteoporotic fracture prevention and treatment outweigh the risk. The present report consists of a rare case of a patient with an atypical diaphyseal femoral stress fracture secondary to prolonged alendronate use.

Keywords: Atypical fracture, bisphosphonate, conservative, sub-trochanteric region


How to cite this article:
Ardebol J, Cahueque M, Mere V, Soto JD. Atypical stress femoral shaft fracture secondary to alendronate therapy. J Orthop Traumatol Rehabil 2020;12:92-4

How to cite this URL:
Ardebol J, Cahueque M, Mere V, Soto JD. Atypical stress femoral shaft fracture secondary to alendronate therapy. J Orthop Traumatol Rehabil [serial online] 2020 [cited 2020 Sep 23];12:92-4. Available from: http://www.jotr.in/text.asp?2020/12/1/92/287705




  Introduction Top


Atypical femoral fractures (AFFs) represent <1% of all hip and femoral fractures and are rare compared to osteoporotic fractures of the femoral neck and intertrochanteric region.[1] Approximately 93.9% of AFFs are associated with bisphosphonate (BP) exposure.[2] Regardless of this adverse effect, the benefits of osteoporotic fracture prevention outweigh the risks. Long-term BP exposure is related to prolonged bone remodeling suppression, which leads to excessive microdamage and increases fracture risk. The American Society of Bone and Mineral Research (ASBMR) established major and minor criteria to define AFFs and facilitate recognition.[2],[3] In the clinical setting, the majority of patients experience prodromal thigh pain. The following case report comprises a patient with a unilateral atypical femoral shaft fracture associated with 5 years of alendronate exposure.


  Case Report Top


The patient was a 70-year-old female, who manifested a painful condition in her right thigh that began after a long walk. She suffered involution of her gait pattern as the painful condition intensified and became capable of walking only at home, with the help of a walking frame. She did not have any history of falls or any local traumatic factor. She also reported that she had been taking calcium supplementation and alendronate for 5 years. She did not present any abnormality during the physical examination, except for discomfort in her right lower limb at the thigh level when walking. Serial radiographs demonstrated thickening of the lateral cortex at the subtrochanteric level [Figure 1]. In light of these findings, magnetic resonance imaging (MRI) of the thigh was requested. This showed the presence of an incomplete fracture of the lateral cortical bone with thickening of the adjacent cortical bone and bone edema in association with slight unilamellar periosteal thickening [Figure 2] and [Figure 3]. Given these factors and the presence of symptoms, surgical treatment was recommended, with intramedullary nail placement. However, the patient decided not to undergo surgery; therefore, an orthosis was placed for 3 months along with the initiation of physical therapy and suspension of alendronate use. After 6 months of conservative treatment, the patient revealed an excellent clinical outcome, without pain and the full range of mobility.
Figure 1: Radiographic image showing thickening of the lateral cortex at the subtrochanteric level

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Figure 2:Coronal view of magnetic resonance imaging revealing a femoral fracture at the lateral cortex

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Figure 3: Axial view of magnetic resonance imaging manifesting bone edema

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  Discussion Top


Approximately 1% of all hip and femoral fractures are AFFs, and diaphyseal fractures represent 3% of femoral fragility fractures. These fractures are uncommon when related to osteoporotic femoral fractures. The age-adjusted incidence rate is 1.8 and 113 of cases/100,000 person-years for <2 and 8–10 years of BP use, respectively. The most commonly affected areas in the femur are the subtrochanteric region and diaphysis. Long-term BP exposure is related to 93.9% of AFFs cases. The median duration of BP therapy in patients with AFF is 7 years.[2],[3],[4]

BPs are the most common drugs prescribed for the treatment of osteoporosis. These medications are pyrophosphate analogs that inhibit osteoclast function. BPs are divided into two groups; nonnitrogenous and nitrogenous. The most commonly used are nitrogenous. Alendronate, an oral nitrogenous BP, is the most frequently related to AFF since it is prescribed more often by physicians. In addition, alendronate maintains efficacy for approximately 10 years.[5] The nitrogenous group inhibits the enzyme farnesyl pyrophosphate synthase, which subsequently will block the prenylation of small GTPase molecules such as Ras, Rho, and Rac. This inhibition will ultimately block osteoclast function and promote apoptosis. Most physicians recommend 3–5 years of treatment to prevent complications secondary to the bone remodeling oversuppression.[1],[6]

In the clinical setting, 70% of patients present with prodromal thigh pain. In patients receiving the long-term BP therapy who refer thigh pain should undergo plain radiography of both femurs. In case the radiography does not report a stress fracture, and clinical suspicion continues, further imaging, such as MRI, should be solicited.[2],[7]

The ASBMR defines an AFF with specific radiographic characteristics. Four of the five major criteria are necessary to complete the diagnosis;

  • The fracture trajectory begins in the lateral cortex and is generally transverse in its direction, although it may become slightly oblique as it reaches the medial aspect of the femur
  • The fracture is associated with no trauma or minimal trauma, as in falling from one's standing height
  • Complete fractures involve both cortices and may be related to a medial spike, and incomplete fractures only the lateral cortex
  • The fracture is noncomminuted or minimally comminuted, and
  • The fracture site has evidence of periosteal and endosteal thickening of the lateral cortex.


Bilateral AFFs are present in up to 63% of cases.[7],[8]

The initial step in management is to discontinue BP therapy and assess the initiation of Vitamin D and calcium supplementation. Complete fractures, such as the patient in the case, are treated surgically with intramedullary nailing. Although delayed healing is found in 26% of cases. Therefore, postoperative treatment with teriparatide should be considered. Teriparatide is utilized to accelerate bone anabolism and fracture healing.[2],[3],[9]


  Conclusion Top


BPs continue as the ideal first-line therapy in patients with osteoporosis. Although the efficacy of these drugs is noted, some rare complications have been reported. The patient in the present case presented the AFF after 5 years of alendronate therapy, which is uncommon, considering it remained at the upper end of the ideal duration of treatment. This patient revealed a unilateral incomplete femoral fracture, which was treated conservatively with an optimal clinical outcome. In other cases, were clinical outcomes remain suboptimal, teriparatide should be considered as well. Orthopedics are advised to reconsider BP treatment duration to optimize safety and to suggest patients to notify promptly when thigh pain surges during treatment.

Declaration of Patient Consent

The authors certify that they have obtained an appropriate patient consent form. In the form, the patient has given her consent to utilize the radiological images and other clinical information to be reported in this journal. The patient understands that her name and initials will not be published, and due efforts will be made to conceal her identity.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Khosla S, Bilezikian JP, Dempster DW, Lewiecki EM, Miller PD, Neer RM, et al. Benefits and risks of bisphosphonate therapy for osteoporosis. J Clin Endocrinol Metab 2012;97:2272-82.  Back to cited text no. 1
    
2.
Saita Y, Ishijima M, Kaneko K. Atypical femoral fractures and bisphosphonate use: Current evidence and clinical implications. Ther Adv Chronic Dis 2015;6:185-93.  Back to cited text no. 2
    
3.
Zheng N, Tang N, Qin L. Atypical femoral fractures and current management. J Orthopaed Translation 2016;7:7-22.  Back to cited text no. 3
    
4.
Borrelli J Jr., Lane J, Bukata S, Egol KA, Takemoto R, Slobogean G, et al. Atypical femur fractures. J Orthop Trauma 2014;28 Suppl 1:S36-42.  Back to cited text no. 4
    
5.
Diab DL, Watts NB. Bisphosphonate drug holiday: Who, when and how long. Ther Adv Musculoskelet Dis 2013;5:107-11.  Back to cited text no. 5
    
6.
Drake MT, Clarke BL, Khosla S. Bisphosphonates: Mechanism of action and role in clinical practice. Mayo Clin Proc 2008;83:1032-45.  Back to cited text no. 6
    
7.
Khan AA, Kaiser S. Atypical femoral fracture. Canadian Med Assoc J 2017;189:E542.  Back to cited text no. 7
    
8.
Shane E, Burr D, Abrahamsen B, Adler R, Brown T, Cheung A, 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;29:1-23.  Back to cited text no. 8
    
9.
Donnelly E, Saleh A, Unnanuntana A, Lane JM. Atypical femoral fractures: Epidemiology, etiology, and patient management. Curr Opin Support Palliat Care 2012;6:348-54.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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