The nanomechanical material properties of iliac crest biopsies from bisphosphonate-treated patients with severely suppressed bone turnover (SSBT) differ from normal and untreated osteoporotic subjects

INTRODUCTION: Bisphosphonates (BPs) are commonly prescribed drugs for the treatment of osteoporosis, a condition of increased fracture risk. BPs inhibit bone resorption, and decrease bone turnover and bone loss. Long-term use of BPs may be associated with changes in the mechanical integrity of the bones of some patients. Odvina et al (2005) were the first to report on a group of nine patients who suffered spontaneous nonvertebral fractures with delayed or absent fracture healing while on long term (3 to 8 years) alendronate, a commonly prescribed BP. The patients received alendronate alone or in combination with estrogen or prednisone, resulting in severely suppressed bone turnover (SSBT). Several cases and case series have since been published. We hypothesized that the compromised integrity of SSBT bone is associated with differences in the mechanical properties of the tissue from normal. In this study, we aimed to characterize and compare the micromechanical properties of iliac crest biopsies taken from SSBT patients, and three comparison groups: untreated osteoporotic fracture patients, age-matched and young normal subjects.