Researchers from Loma Linda (Calif.) University and Saint Louis University compared the impact of modular head screws versus preassembled tulip head screws on reducing the fracture rate during spine surgery using the cortical bone trajectory technique.
The study used 24 frozen lumbar vertebrae from five cadavers. The researchers placed preassembled head screws and modular head screws into the right and left pedicles of each vertebra. The study included X-rays for measuring angle deviations between tapped and final screw trajectories and researchers performed pullout tests.
Journal of Clinical Neuroscience published the study.
Here are five notes.
1. Researchers reported 70.8 percent of the spinous processes required excision to align with proper trajectories.
2. Six fractures happened with the preassembled screws compared to one fracture with the modular head screws.
3. The study revealed the midline-to-medial wall distance of the pedicle proved a marginally significant predictor of fracture.
4. Researchers found no statistical differences between the two screws' pullout loads.
5. The researchers concluded modular head screws presented a "significantly lower fracture rate than preassembled head screws for cortical bone trajectory in osteoporotic bone."