Enhancing screw fixation in poor bone quality, an unmet clinical need

Abstract

A significant unmet clinical need in orthopaedic traumatology is improved bone screw fixation in poor quality bone. It is estimated that over 100 million1 screws are implanted worldwide annually. Loosening & migration are significant clinical complications in osteoporotic fractures. In the proximal humerus and femur failure rates may be as high as 40% and 7% respectively2,3. Bone screws should assure adequate fixation at early (days) and late (weeks) time points, as well as easy removal at revision. It should be possible to design screws/techniques that would improve fixation in weak bone but this is an area neglected by the manufacturers. Paradoxically bone screws are contraindicated for use in osteoporotic bone in instructions for use (IFU) although osteoporotic fractures are the most frequent application for screw fixation. Techniques that may enhance screw stability in weak bone, such as the addition of cement at the time of surgery or use of hydroxyapatite coatings have long been under consideration. This paper considers bone augmentation, what has been learned and goes on to suggest what could be done to gain clinical acceptance of these techniques.