of atypical femoral fractures is a known complication of chronic bisphosphonate therapy;
however, the finding of atraumatic lumbar pedicle fractures without a prior history of spinal surgery or
contralateral spondylolysis is rare. While a few cases of osteoporotic pedicle fractures associated with
adjacent vertebral compression fractures have been reported, only a single case of isolated atraumatic
bilateral pedicle fractures has been published in a patient who had been on chronic risedronate therapy
of 10-year duration.
Case Report: The present case report illustrates a 63-year-old man who developed isolated atraumatic bilateral lumbar
pedicle fractures after 3 years and 5 months on alendronate treatment. The patient’s past medical history
had been significant for osteoporosis with a lumbar spine T-score of -2.7. At the time of initial diagnosis,
a comprehensive work-up for secondary causes of osteoporosis proved to be negative; this was followed
by initiation of bisphosphonate treatment with 70 mg of alendronate once per week. Ten months after
starting bisphosphonate therapy, he underwent magnetic resonance imaging (MRI) of the lumbar spine
for low back pain that had not responded to conservative management, with imaging not revealing any
evidence of pedicle fractures or pedicle stress reaction. He was again seen in the spine clinic, for atraumatic
exacerbation of his chronic low back pain with concurrent right lower extremity radiation, 6 months
after stopping bisphosphonate therapy. Since the patient failed to respond to conservative management
over the ensuing 6 months, a repeat MRI was obtained, which showed new acute/subacute bilateral L5
pedicle fractures.
Conclusion: An isolated atraumatic lumbar pedicle fracture may be an additional type of atypical fracture associated
with chronic bisphosphonate therapy in an osteoporotic patient.
Key words: Chronic low back pain, bisphosphonate, alendronate, pedicle fracture
Pain
Medicine
Lumbar spine MRI in upright position for diagnosing acute and chronic low back pain: statistical analysis of morphological changes
