Dental Cement Augmentation Increases Pullout Strength With Comparable Removal Torque for Lateral Mass Screws

Area of Science:

• Biomechanical and basic science research.
• Spinal surgery and fixation techniques.

Background:

• Spinal screw fixation can fail prematurely, particularly in patients with poor bone quality.
• Traditional polymethyl methacrylate (PMMA) augmentation has limitations in the cervical spine due to bone size and extravasation risks.
• Dental cement offers a potential alternative for augmenting posterior cervical spinal screw fixation.

Purpose of the Study:

• To assess the efficacy of dental cement augmentation for lateral mass screws in the cervical spine.
• To determine if dental cement improves screw fixation strength.
• To evaluate the impact of dental cement on screw removal torque.

Main Methods:

• Biomechanical testing on 15 cadaveric cervical vertebrae.
• Lateral mass screw fixation performed with and without dental composite augmentation.
• Pull-out testing to measure axial load until failure.
• Torque testing to assess the force required for screw removal.

Main Results:

• Augmented screws demonstrated significantly higher pullout strength (263.8±79.4N) compared to non-augmented screws (127.7±21.2N).
• No significant difference was found in the mean torque required for screw removal between augmented and non-augmented groups.
• Dental composite was visible on X-ray, indicating radio-opacity.

Conclusions:

• Dental composite augmentation enhances the pullout strength of cervical lateral mass screws.
• This augmentation technique does not alter the torque required for screw removal.
• Dental cement augmentation may provide a safe and effective method to improve fixation in subaxial cervical spine fusion procedures.