[Characterization of biomechanical behavior of the lumbosacral spine in dogs. Characteristics related to spondylosis and disk degeneration].

The in vitro and static biomechanical behaviour of vertebrae with spondylosis were compared with that of healthy vertebrae. In the dog, spondylosis predominates in the lombo-sacral spine which was chosen as an animal model for spontaneous spondylosis. Fourteen surgical specimens were take from German shepherd dogs which had been submitted to right and left lateral flexion, saggital flexion and dorsal flexion. Angular displacements were recorded with an analyser of spinal movement. Our results demonstrated diseased vertebrae have more flexibility than healthy vertebrae in the sagittal and frontal planes than but less so for dorsal flexion. In Addition, diseased vertebrae tend to move upward during lateral flexion. Exeresis of ligament and capsular structures has allowed us to demonstrate the importance of these structures in maintaining spine stability in the sagittal plane and in joint coaptation. Exeresis of the facet joints led to the demonstration of the role of these structures in the maintenance of spine stability in the transverse plane in cases of disc degeneration.