The effect of posterior spinal fixation with acrylic cement on the vertebral growth plate and intervertebral disc in dogs.

We have attempted to clarify the serial histological changes in the growing spine of dogs following posterior fixation with acrylic cement. Twenty-four male mongrel dogs aged 8 weeks were used for the study. The lumbar spine from L.3 to L.5 was fixed posteriorly with acrylic cement. Three dogs were then sacrificed every four weeks up to 32 weeks, and the histological changes of the vertebral disc, growth plate and vertebral bodies were observed by light microscopy. Thinning of the growth plate and distortion of the cartilage columns has been demonstrated, but premature fusion of the growth plate did not result and vertebral body growth continued. Anterior wedging of the intervertebral disc was seen with some thinning of the bony trabeculae of the vertebral body. Degeneration of the nucleus pulposus resulted, with replacement by fibrous tissue. The normal horizontal arrangement of the fibres of the annulus fibrosus altered to a vertical configuration by 32 weeks.