E-ISSN: 1019-5157
ISSN: 2651-5024
Research
Biomechanical Evaluation of Geometry, Size, and Integrated Fixation Concepts on Static and Dynamic Subsidence of Cervical PEEK Interbody Cages
Fatma Kübra Erbay Elibol✉
biomedical engineering, TOBB University of Economics and Technology
Accepted: 30/08/2026
Article in Press
Corresponding Author:
Fatma Kübra Erbay Elibol (fatmakubra.erbay@gmail.com)
Abstract
Aim
To biomechanically evaluate the influence of cage geometry, dimensions, and integrated fixation concepts on the insertion–expulsion characteristics, compression behavior, and static and dynamic subsidence performance of cervical polyether ether ketone (PEEK)[P1.1] interbody cages.
Material and Methods
Five cervical PEEK interbody cage designs representing different dimensions, geometrical configurations, and fixation concepts (pin, blade, and blade-plus-pin) were evaluated biomechanically. Insertion and expulsion, static compression, static subsidence, and dynamic subsidence tests were performed using polyurethane foam blocks.
Results
The blade-and-pin configuration exhibited the highest expulsion force among the assessed designs. No significant differences were observed in static subsidence stiffness parameters (Ks and Kp)[P2.1]. Dynamic subsidence testing revealed significant load-dependent differences among the assessed designs. Under moderate dynamic loading conditions (50% of the static subsidence yield load), the ellipsoidal pin-based cage demonstrated greater subsidence than the box-shaped pin-based cage of comparable dimensions. The larger pin-based cage exhibited greater subsidence than its smaller counterpart. Under high dynamic loading conditions (75% of the static subsidence yield load), the larger pin-based cage continued to demonstrate significantly greater subsidence than its smaller counterpart. No significant differences in dynamic subsidence performance were observed between the blade-only and blade-plus-pin configurations.
Conclusion
The investigated cervical PEEK cage designs demonstrated distinct biomechanical performance profiles across insertion–expulsion, compression, static subsidence, and dynamic subsidence testing. Under laboratory conditions, the blade-and-pin configuration demonstrated the highest expulsion force. Certain cage designs with higher structural stiffness were associated with increased dynamic subsidence under cyclic loading conditions despite similar static subsidence stiffness characteristics. These findings suggest that static compression and static subsidence parameters may not adequately predict dynamic subsidence behavior under cyclic loading conditions. The findings also highlight the importance of incorporating dynamic subsidence testing into the preclinical biomechanical evaluation of cervical interbody cages.
To biomechanically evaluate the influence of cage geometry, dimensions, and integrated fixation concepts on the insertion–expulsion characteristics, compression behavior, and static and dynamic subsidence performance of cervical polyether ether ketone (PEEK)[P1.1] interbody cages.
Material and Methods
Five cervical PEEK interbody cage designs representing different dimensions, geometrical configurations, and fixation concepts (pin, blade, and blade-plus-pin) were evaluated biomechanically. Insertion and expulsion, static compression, static subsidence, and dynamic subsidence tests were performed using polyurethane foam blocks.
Results
The blade-and-pin configuration exhibited the highest expulsion force among the assessed designs. No significant differences were observed in static subsidence stiffness parameters (Ks and Kp)[P2.1]. Dynamic subsidence testing revealed significant load-dependent differences among the assessed designs. Under moderate dynamic loading conditions (50% of the static subsidence yield load), the ellipsoidal pin-based cage demonstrated greater subsidence than the box-shaped pin-based cage of comparable dimensions. The larger pin-based cage exhibited greater subsidence than its smaller counterpart. Under high dynamic loading conditions (75% of the static subsidence yield load), the larger pin-based cage continued to demonstrate significantly greater subsidence than its smaller counterpart. No significant differences in dynamic subsidence performance were observed between the blade-only and blade-plus-pin configurations.
Conclusion
The investigated cervical PEEK cage designs demonstrated distinct biomechanical performance profiles across insertion–expulsion, compression, static subsidence, and dynamic subsidence testing. Under laboratory conditions, the blade-and-pin configuration demonstrated the highest expulsion force. Certain cage designs with higher structural stiffness were associated with increased dynamic subsidence under cyclic loading conditions despite similar static subsidence stiffness characteristics. These findings suggest that static compression and static subsidence parameters may not adequately predict dynamic subsidence behavior under cyclic loading conditions. The findings also highlight the importance of incorporating dynamic subsidence testing into the preclinical biomechanical evaluation of cervical interbody cages.
Keywords
Cervical cage
Expulsion resistance
Dynamic subsidence