Published in:
01-12-2022 | Femoral Fracture | Case Report
Atypical femoral fracture in a bisphosphonate-naïve patient on denosumab for osteoporosis
Published in: Archives of Osteoporosis | Issue 1/2022
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Summary
A post-menopausal Caucasian woman sustained an atypical femoral fracture (AFF) after 5-years continuous denosumab for osteoporosis without prior bisphosphonate exposure. This is only the fifth case reported of AFF in a bisphosphonate-naïve patient receiving denosumab for osteoporosis. Although rare, physicians should consider AFF in patients taking denosumab even without prior bisphosphonate exposure.
Introduction
Denosumab has demonstrated overwhelmingly favourable skeletal benefit/risk profile in managing post-menopausal osteoporosis with up to 10-year exposure in the extension of the pivotal FREEDOM randomised placebo-controlled trial. Four previous cases of atypical femoral fracture have been reported in bisphosphonate-naïve patients receiving denosumab for osteoporosis.
Methods
We present an 85-year-old Caucasian post-menopausal woman without prior fragility fracture who sustained unilateral atypical femoral fracture after 5-years continuous subcutaneous denosumab for osteoporosis. She had no prior bisphosphonate or glucocorticoid exposure and had known chronic kidney disease.
Results
X-ray scan demonstrated complete, non-comminuted left proximal femoral shaft fracture meeting radiographic criteria for an atypical femoral fracture. Computed tomography (CT) scan lower limbs revealed unusual side-by-side appearance of proximal and distal fragments of left proximal femur. DXA BMD was artefactually elevated at lumbar spine (1.504 g/cm2, T-score + 2.5) and low-normal at right femoral neck (0.856 g/cm2, T-score -1.0). Serum biochemistry showed renal impairment at baseline (eGFR 30 mL/min/1.73m2). Low-normal serum C telopeptide of type 1 collagen (CTX) (230 ng/L) indicated therapeutic suppression of bone resorption.
Conclusion
The patient underwent intramedullary nailing of the femur and denosumab was ceased. This is only the fifth case reported of atypical femoral fracture in a bisphosphonate-naïve patient receiving denosumab for osteoporosis. Although rare, physicians should maintain a high index of suspicion for atypical femoral fracture in a patient taking denosumab even without prior bisphosphonate exposure.