Biomechanical effects of a titanium intervertebral cage as a stand‐alone device, and in combination with locking plates in the canine caudal cervical spine

Abstract

Objective To evaluate the change in ex vivo biomechanical properties of the canine cervical spine, due to an intervertebral cage, both as a stand‐alone device and in combination with plates. Study Design Experimental ex vivo study. Animals Cervical spinal segments (C5‐C7) from eight canine cadavers. Methods The range of motion (ROM) and elastic zone stiffness (EZS) of the spines were determined with a four‐point bending device in flexion/extension, lateral bending, and axial rotation for four conditions: native, discectomy, cage (at C6‐C7), and cage with plates (at C6‐C7). The disc height index (DHI) for each condition was determined using radiography. Results Discectomy resulted in overall increased ROM (p < .01) and EZS (p < .05) and decreased DHI (p < .005) when compared to the native condition. Placement of the cage increased DHI (p < .001) and restored total ROM during flexion/extension, lateral bending and axial rotation, and EZS during flexion/extension to the level of the native spine. Application of the plates further reduced the total ROM during flexion/extension (p < .001) and lateral bending (p < .001), but restored ROM in extension and EZS during lateral bending. No implant failure, subsidence, or significant cage migration occurred during loading. Conclusion An anchorless intervertebral cage used as a stand‐alone device was able to restore the disc height and spinal stability to the level of the native cervical spine, whereas the addition of plates further reduced the spinal unit mobility. Clinical Significance This study implies that the intervertebral cage may be used as a stand‐alone device in the spinal unit fixation in the canine cervical spine.

Development of an intervertebral disc prosthesis prototype for the canine cervical spine

“…This allows the screws to be fixed to a plate, acting as an internal fixator (FERRIGNO et al, 2011). Thus, this locking plate-screw system enables angular stability and is not dependent on the frictional force between the plate and bone and, thereby, eliminates plate contouring and allows proper blood supply (BEISHUIZEN et al, 2021). Additionally, the use of monocortical screws prevents inadvertent penetration into the spinal canal.…”

Comparison of Cervical Stabilization with Transpedicular Pins and Polymethylmethacrylate versus Transvertebral Body Polyaxial Screws with or without an Interbody Distractor in Dogs

“…31 Another limitation that should be considered is the use of the same specimens in all groups, as previously reported. 30,33,34 The pins in the pin-PMMA groups were inserted after three holes were created in the vertebral body of each vertebra, which may lead to loosening of the pins if the pin enters the same hole previously created. This, in turn, would affect the final result.…”

“…12 34 Extension and flexion were performed sequentially in each specimen, based on previous studies. 30 33 34…”

“…12,34 Extension and flexion were performed sequentially in each specimen, based on previous studies. 30,33,34 Tests were first performed on the vertebral column segments without the implants. The same segments were then modified and tested as part of the polyaxial þ distractor group, polyaxial À distractor group and pin-PMMA group.…”

“…The specimens used in the pilot study were not reused for the main study. Based on the results from the pilot study and previously published studies, [31][32][33] the torque was limited to AE 2 Nm.…”