Previous ex vivo biomechanical studies have shown that kyphoplasty with polymethylmethacrylate cement increases vertebral body (VB) strength and restores VB stiffness and height after compression fracture. The purpose of the current study was to determine if a hydroxyapatite cement used as a void filler during kyphoplasty provides mechanical stabilization similar to that of a polymethylmethacrylate cement.