Combined effects of zoledronate and mechanical stimulation on bone adaptation in an axially loaded mouse tibia.

BACKGROUND local bisphosphonate delivery may be a solution to prevent periprosthetic bone loss and improve orthopedic implants fixation. In load-bearing implants, periprosthetic bone is exposed to high mechanical demands, which in normal conditions induce an adaptation of bone. In this specific mechanical situation, the modulation of the bone response by bisphosphonate remains uncertain. METHODS we assessed the combined effects of zoledronate and mechanical loading on bone adaptation using an in-vivo axial compression model of the mouse tibia and injections of zoledronate. Bone structure was quantified with in-vivo microCT before and after the period of stimulation and the mechanical properties of the tibias were evaluated with 3 point-bending tests after sacrifice. FINDINGS axial loading induced a localized increase of cortical thickness and bone area. Zoledronate increased cortical thickness, bone perimeter, and bone area. At the most loaded site of the tibia, the combined effect of zoledronate and mechanical stimulation was significantly smaller than the sum of the individual effects measured at the same site in the control groups. INTERPRETATIONS the results of this study suggested that a negative interaction between zoledronate and mechanical loading might exist at high level of strain.