Comparison of the biomechanical properties of a ventral cervical intervertebral anchored fusion device with locking plate fixation applied to cadaveric canine cervical spines.

OBJECTIVE:
To evaluate fixation properties of a new intervertebral anchored fusion device and compare these with ventral locking plate fixation.
STUDY DESIGN:
In vitro biomechanical evaluation.
ANIMALS:
Cadaveric canine C4-C7 cervical spines (n = 9).
METHODS:
Cervical spines were nondestructively loaded with pure moments in a nonconstraining testing apparatus to induce flexion/extension while angular motion was measured. Range of motion (ROM) and neutral zone (NZ) were calculated for (1) intact specimens, (2) specimens after discectomy and fixation with a purpose-built intervertebral fusion cage with integrated ventral fixation, and (3) after removal of the device and fixation with a ventral locking plate.
RESULTS:
Both fixation techniques resulted in a decrease in ROM and NZ (P < .001) compared with the intact segments. There were no significant differences between the anchored spacer and locking plate fixation.
CONCLUSION:
An anchored spacer appears to provide similar biomechanical stability to that of locking plate fixation.