Intervertebral biomechanics of locking compression plate monocortical fixation of the canine cervical spine.

ABSTRACT

OBJECTIVE: To evaluate the use of a locking compression plate (LCP) with monocortical screw purchase for stabilization of the canine cervical spine. STUDY DESIGN: Experimental study. ANIMALS Cadaveric canine cervical spine specimens (n = 7). METHODS: Flexion and extension bending moments were applied to canine cadaveric specimens (C3-C6) in 4-point bending, before and after creation of a ventral slot at C4-C5, and after fixation with a 5 hole, 3.5 mm LCP with monocortical screw placement. Screw placement and penetration into the vertebral canal were determined by radiography. Range of motion, stiffness, and energy for passive physiologic loads were determined for the C3-C4, C4-C5, and C5-C6 vertebral motion units (VMU). Monotonic failure properties were determined for cervical extension. Effects of treatments on biomechanical variables were assessed using repeated measures analysis of variance and least square means (P ≤ .05). RESULTS: The ventral slot procedure increased range of motion at the treated VMU. Plate fixation decreased range of motion, increased stiffness, and decreased energy at the treated VMU. No changes were observed at adjacent VMUs. None of the screws penetrated the vertebral canal. Mean (± SD) yield bending moment of plate stabilized, slotted spines was 15.6 ± 4.6 N m. CONCLUSION: LCP fixation with monocortical screws stabilized the canine cervical spine.