A radiologic determination of the different screw cutting patterns in cut and uncut orthopedic cortical screws using a novel imaging technique.

Abstract

We hypothesize that cut screws will deform in a manner that increases the core and outer diameters of the screw hole compared to uncut controls, and effects will be more pronounced in titanium screws. We used biomechanical polyurethane foam blocks to simulate cortical bone. We organized four groups of stainless steel and titanium cut and uncut screws. Blocks were fitted with a jig to ensure perpendicular screw insertion. We imaged the blocks using digital mammography and measured them using PACS software. Power analysis determined a power of 0.95 and an alpha error of 0.05. Highly statistically significant differences in core diameter were found after cutting stainless steel and titanium screws. Cutting stainless steel screws increased core diameter by 0.30 mm (95% CI, 0.16 to 0.45; p < .001). Titanium screws' core diameter increased by 0.45 mm (95% CI, 0.30 to 0.61; p < .001). No significant differences were found in the outer diameters of stainless steel and titanium screws after cutting. Titanium and stainless steel screw tracts demonstrated screw core diameter and screw thread pattern deformation after cutting. Titanium screws demonstrated more significant effects.