Osteoclast abnormalities in fractured bone during bisphosphonate treatment for osteoporosis: a case report

Bisphosphonates have been widely used in the treatment of an array of bone disorders. Recent complications have included unusual femoral fractures in patients who have received long term bisphosphonate treatment for osteoporosis. Although it has been shown that bisphosphonates are effective by blunting osteoclast resorption, there has been little morphologic description of the local tissue activity at the site of these unusual fractures. To evaluate for local changes to bone morphology at the fracture site in patients presenting with a bisphosphonate-related femur fracture, a sample of cortical bone was obtained at the site of a bisphosphonate fracture and was processed in a nondecalcified manner. The specimen was evaluated for potential cellular changes consistent with bisphosphonate treatment. Significant osteoclast abnormalities at the fracture site were found in a 69-year-old woman treated for 2 years with Fosamax substantiating that bone remodeling at this site is distinctly abnormal. Addressing the osteoclast dysfunction should be a focus of future therapeutic attention and intervention.