The Trans-Spinous Crosslink Increases the Pull-Out Strength of the Pedicle Screw Instrumentation

Area of Science:

• Spinal surgery
• Orthopedic biomechanics
• Spinal instrumentation

Background:

• Pedicle screws are crucial for spinal fixation, but screw loosening remains a clinical concern.
• Current spinal constructs rely on pedicle screws to anchor fixation devices, sharing the load.
• Enhancing construct stability and preventing screw loosening are key goals in spinal fusion surgery.

Purpose of the Study:

• To investigate the efficacy of the trans-spinous crosslink technique in improving pedicle screw pull-out strength.
• To evaluate if an additional anchoring point via the spinous process can enhance construct stability.
• To determine the biomechanical impact of the trans-spinous crosslink on screw loosening prevention.

Main Methods:

• Twenty-four sheep lumbar vertebrae were used, instrumented with bilateral pedicle screws and connected by a crosslink.
• Vertebrae were randomly assigned to either a trans-spinous crosslink group or a control group.
• Pull-out force was measured using a mechanical testing machine to assess construct strength.

Main Results:

• The trans-spinous crosslink group exhibited a mean pull-out force of 1949 ± 361.55 N.
• The control group showed a mean pull-out force of 1338.57 ± 220.26 N.
• The difference in pull-out force was statistically significant (p < 0.001), with 99.9% confidence.

Conclusions:

• The trans-spinous crosslink technique effectively increases the pull-out strength of spinal constructs.
• This method provides an additional anchoring point, reducing the load on individual pedicle screws.
• The trans-spinous crosslink shows promise in preventing screw loosening and enhancing spinal fixation stability.