The safety range of acute shortening of spinal column after total vertebrectomy

Abstract

Objective To investigate the change of morphologic and neurological function of spinal cord after acute spinal column shortening, to enlighten the safety range of acute shortening on the spinal column following total spondylectomy. Methods One-hundred and twenty New Zealand white rabbits were used as experimental animals. The animals were randomly divided into three groups: single-level laminectomy group(A), double-level iaminectomy group (B), and three-level laminectomy group(C). Each group was divided into four subgroups according to the percent of spinal column shortening: 25%, 50%, 75% and 100% subgroups. After total vertebrectomy of L3, we performed spinal column shortening and measured the diameter and length of spinal cord, angle between spinal cord and L3 nerve root, the latency and amplitude of somatosensory evoked potential (SEP) accordingly. Tarlov scales were recorded 72 h after surgery, and HE stain was used to observe the histopathological changes of the spinal cord. Results The morphology and neurological function of spinal cord had no significant change when spinal column shortening was less than 50% in all groups (P>0.05). The morphology and neurological function were significantly changed when spinal column shortening was 75% in group A (P<0.05), and massive hemorrhages and shrinkage of neurons were observed in the pathological sections. The morphology and neurological function of spinal cord had no significant change until spinal column shortening was more than 75% in group B and C. There was no significant difference between group B and C. Conclusion The safety range of spinal column shortening after vertebrectomy and single laminectomy was no more than 50% of vertebral height. However, it can be extended to 75% by performing double or three levels laminectomy to avoid spinal cord injury caused by spinal cord kinking. The range of laminectomy has obvious effect on the morphologic change and neurological function of spinal cord after spinal column shortening. Key words: Osteotomy; Spine; Laminectomy; Spinal cord injuries