Bisphosphonate Use Beyond 7 Years May Alter Bone Quality in Osteoporosis

Oral bisphosphonate therapy that lasts longer than 7 years may be associated with a decline in osteoblastic activity among women with osteoporosis, which could alter bone strength or fracture resistance, according to findings of a new analysis presented at the American Society for Bone and Mineral Research 2019 Annual Meeting. The findings suggest that approximately 6 to 7 years of bisphosphonate use offers the most benefit to the bone.

To reach their conclusions, David Pienkowski, PhD, from the University of Kentucky, and colleagues retrospectively analyzed microcomputed tomography images of 45 iliac crest bone samples from women with osteoporosis who received treatment with oral bisphosphonates for 1 to 20 years. The images were evaluated for bone structure, strength, and stiffness using finite element analysis.

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The researchers also used nanoindentation to measure bone modulus and histological staining to assess microcrack number, density, and length.

Results showed that as the duration of bisphosphonate use increased, so did the finite element analysis–estimated bone strength. This strength peaked at approximately 7.3 years and then declined.

Bone modulus increased as the duration of bisphosphonate use increased; this effect peaked at approximately 6 years and then plateaued. Microcrack density also increased with the duration of bisphosphonate treatment, but the upward trend of mean microcrack length was nonsignificant.

The authors noted that a decline in osteoblastic activity after bisphosphonate use beyond 7 years could be attributed to reduced microstrain-mediated cell activity or late-onset action of bisphosphonates.

“A subsequent reduction in osteoblastic activity, following initial reductions in osteoclast activity, may account for observed declines in structure-related mechanical competence. … Collectively these data suggest that BP use exceeding [approximately] 7 years requires careful consideration.”

—Colleen Murphy

Reference:

Pienkowski D, Wood C, Malluche H. Bone quality and long-term bisphosphonate use in women with osteoporosis [Abstract #1088]. Presented at: American Society for Bone and Mineral Research 2019 Annual Meeting; September 22, 2019; Orlando, FL.