Comparing the Fixation of a Novel Hollow Screw Versus a Conventional Solid Screw in Human Sacra Under Cyclic Loading

Abstract

Screw rotation tended to gradually increase to six degrees, after which the screw was grossly loose. Overall, the hollow screw required fewer loading cycles (P = 0.004) and less applied moment (P = 0.003) to achieve the same magnitude of screw rotation as the solid screw. To achieve 6 degrees of screw rotation, the number of loading cycles were 6301 +/- 2161 and 11151 +/- 4221 for hollow and solid screws, respectively. The corresponding applied moments were 3.5 +/- 1.0 Nm and 5.8 +/- 2.0 Nm. CONCLUSION.: The novel hollow screw was less resistant to loosening when compared with a conventional solid pedicle screw in this sacral model under cyclic loading.