Low-energy femoral shaft fracture in elderly patient with prolonged use of alendronate

Fractures in the proximal femur occur in female and male elderly population due to low-energy trauma in osteoporotic bones. In order to prevent these fractures, treatment of osteoporosis has been indicated, particularly using biphosphonates(¹).

Alendronate was the first drug approved by the Food and Drug Administration (FDA), in 1995, to treat osteoporosis(²). This drug acts in bone metabolism, inhibiting osteoclasts, inducing their apoptosis(³), raising the bone mineral density and reducing the incidence of osteoporotic fractures(⁴).

In the past years, some authors described an unusual shaft femoral fracture in elderly women undergoing prolonged treatment of osteoporosis with biphosphonates. These fractures were associated with low-energy trauma or no evidence of any trauma event(⁵,⁶).

Femoral structure submitted to physiological stress results in microdamages to bone microstructure. The inhibition of osteoclasts may also lead to severe suppression in bone turnover, leading to accumulation of microdamage(⁷–⁹). These processes may make bone brittle and cause unexpected and uncommon femoral fractures.

A recent increase in the incidence of such fractures in patients on alendronate therapy led some authors to conduct a retrospective review of these cases. A characteristic fracture configuration suggestive of an insufficiency stress fracture was identified on plain radiographs. This consists of a cortical thickening in the lateral side of the subtrochanteric region, a transverse or short oblique fracture, and a medial cortical spike (Figure 1).

Figure 1
Stress fracture in the lateral córtex.

A retrospective study evaluating 19 patients with this fracture pattern among 70 patients with low-energy shaft fractures was 98% specific to alendronate users(⁶). Thus, alendronate treatment might be stopped for a while after five years to prevent severe suppression of bone turnover and subsequent stress fractures(⁷).

• Study carried at Hospital Israelita Albert Einstein – HIAE, São Paulo (SP), Brasil.

REFERENCES

• ¹
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  FDA- approved Drugs. USA Food and Drug Administration 1995 (date last accessed 1^st February 2007).
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  Wells GA, Cranney A, Peterson J, Boucher M, Shea B, Robinson V, Coyle D et al. Alendronate for the primary and secondary prevention of osteoporotic fracture in postmenopausal women. Cochrane Database Syst Rev. 2008;(1):CD001155
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  Neviaser AS, Lane JM, Lenart BA, Edobor-Osula F, Lorich DG. Low-energy femoral shaft fractures associated with alendronate use. J Orthop Trauma. 2008;22(5):346-50.
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  Yamaguchi T, Sugimoto T. [New development in bisphosphonate treatment. When and how long should patients take bisphosphonates for osteoporosis?]. Clin Calcium. 2009;19(1):38-43. [Japanese].
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  Goh SK, Yang KY, Koh JSB, Wong MK, Chua DT, Howe TS. Subtrochanteric insufficiency fractures in patients on alendronate therapy: A CAUTION. J Bone Joint Surg Br. 2007;89(3):349-53.
• ⁹
  Visekruna M, Wilson D, McKiernan FE. Severely suppressed bone turn over and atypical skeletal fragility. J Clin Endocrinol Metab. 2008;93(8):2948-52.

Publication Dates

• Publication in this collection
  Jan-Mar 2011

History

• Received
  30 June 2009
• Accepted
  12 Apr 2010