An expandable anchor for fixation in osteoporotic bone.

With the aging population, osteoporosis and osteoporotic fractures are becoming more prevalent. Adequate screw fixation in this type of bone is difficult. Screws are often cemented in bone to help obtain purchase. However, cement augmentation is not without problems. Here we present an expandable anchor for fixation in osteoporotic bone that does not require cement. We compared the ultimate holding power of this expandable anchor to a standard solid screw of similar dimensions. The solid screw and the expandable anchor were both placed into fresh frozen lumbar vertebral bodies and pulled out using a mechanical testing system. The expandable anchor had a 74% greater holding power compared to the standard screw (P = 0.02). The expandable anchor provides a significant increase in holding power without the problems associated with cement. This prototype anchor is promising for fixation in osteoporotic bone and warrants further evaluation.