[Cement distribution in vertebroplasty pedicle screws with different designs]

The effects of deteriorated bone density become particularly apparent in cases where spinal instrumentation is needed. Cement augmentation of pedicle screws for better bone purchase became the subject of many studies, which proved the biomechanical superiority and the increased pullout strength of cement augmented screws. Inadequate, and sometimes dangerous, cement distribution made the need for development of special implants inevitable. Pedicle screws with side openings and a central drill hole allow cement augmentation through the implant and increase not only the screw diameter but also the interfacial strength between the three components (screw-cement-bone). Accordingly cement distribution can be affected by the selection of the side openings (size and position). Screws with conical core and distally situated side openings facilitate the development of uniform cement dough.