Dual-threaded pedicle screws provided the strongest primary pull-out strength for spinal fixation, according to a study published in Spine.
The researchers tested the pull-out strengths of three different pedicle screw designs (single-thread, mixed-thread, dual-thread) in standardized polyurethane foam in three sequences.
Four things to know:
1. The primary pull-out strength was similar across screw designs, although dual-thread screws showed higher primary pull-out strength (2628.8 newtons) compared to single-thread screws (2184.4 newtons).
2. For revision pull-out strength, the mixed-thread screws had an 18.6 percent reduction in pull-out strength. Revision with a larger diameter screw improved the pull-out strength back to baseline.
3. The researchers found no significant reduction in revision pull-out strength for single and dual-thread screws.
4. In cases in which mixed-threaded screws must be revised (at the index or revision surgery), surgeons should consider using larger diameter screws to improve the pull-out strength, the study authors concluded.