Canine Lumbar Spinal Internal Fixation Techniques A Comparative Biomechanical Study

The stability (flexural rigidity) and strength of five canine spinal internal fixation techniques were quantitated and compared to each other and to the rigidity and strength of the intact spine. The techniques were applied to isolated canine lumbar spines (L2–L5) on which a complete spinal injury was surgically simulated at L3–L4. The spine-implant preparations were subjected to four-point bending and tested once to failure in flexion. The bending moment vs. L3–L4 angular deformation curves were recorded; rigidity and load sustained at failure (10° angular deformation) were compared. The combination of dorsal spinous process plate and dorsolateral vertebral body plate was the most rigid and most strong of the techniques tested. The dorsolateral vertebral body plate was the most rigid and most strong of the individual techniques, followed by the dorsal spinous process plate and the polymethylmethacrylate-pin technique. Vertebral body crosspins provided the least strength and stability of any of the techniques tested.