Can Partially Threaded Cannulated Screws Be Better Designed to Maximize Purchase in the Sacrum?

Sacroiliac screw fixation involves the use of cannulated, partially or fully threaded screws. Current partially threaded screws have standardized thread lengths involving a small portion of the screw regardless of its overall length. Forty uninjured computed tomography images were evaluated for distances from the lateral iliac cortex to the lateral sacral cortex at the first and second sacral segments. No difference in measurements were observed for gender, age, or body mass index. Using a smooth segment value of 32 mm, a significant increase in thread lengths is achievable allowing for a novel sacroiliac screw design to achieve greater purchase in the sacrum.