DOI: 10.1097/bn9.0000000000000152 ISSN: 3066-8905

Biomechanical Evaluation of a Novel Anterior Plating System Compared With One-Screw and Two-Screw Fixation for Type II Odontoid Fractures

Friederike E. Roch, Anna Krüger, Friederike S. Klockner, Marc-Pascal Meier, Hassan A. Malik, Lennart Viezens, Leon-Gordian Leonhardt, Wolfgang Lehmann, Lukas Weiser, Paul J. Roch
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Study Design:

Cadaveric biomechanical analysis.

Objective:

To compare the biomechanical stability of plate osteosynthesis (POS), two-screw fixation (2S), single-screw fixation (1S), and headless compression screw fixation (HCS) under coupled multidirectional cyclic loading conditions.

Summary of Background Data:

Anterior screw fixation is an established motion-preserving treatment for type II odontoid fractures. However, the optimal fixation strategy remains controversial, and comparative biomechanical data on POS and established anterior screw fixation techniques remain limited.

Materials and Methods:

A total of 26 C1–C3 specimens (six POS, six headless compression screw, six 1S, and eight 2S) were included. Standardized type II odontoid fractures were created, followed by osteosynthesis according to group allocation. Specimens were subjected to cyclic loading using a custom apparatus enabling combined motion patterns. Construct stability and screw loosening were assessed by visual inspection, mechanical testing, and camera-based tracking analysis. Visual force-to-loosening data were analyzed using Kaplan-Meier methods because specimens without detectable loosening at the maximum load were treated as right-censored observations.

Results:

Mechanical testing and image-based analysis demonstrated significantly higher stability for 2S compared with 1S ( P =0.045 and 0.007, respectively). No additional statistically significant differences were observed between the remaining constructs. Kaplan-Meier analysis of visual screw loosening showed no significant overall difference between groups ( P =0.066). After adjustment for bone mineral density, the difference between 2S and 1S remained significant in both mechanical and camera-based analyses.

Conclusion:

Under coupled multidirectional cyclic loading, 2S demonstrated greater biomechanical stability than 1S and showed the highest mean stability among the investigated constructs. POS did not demonstrate superior biomechanical stability compared with established anterior screw fixation techniques. The findings support further optimization and investigation of the POS concept.

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