[Improvement of spinal cord semi-transected and lump defect model by quantitate semi-transected blade in rats]

To investigate the effect of quantitative semi-transected blade on the improvement of spinal cord semi-transected and lump defect model.

Forty-eight male Sprague Dawley rats (weighing 220-250 g) were divided into the experimental group (n = 24) and control group (n = 24). The spinal cord semi-transected and lump defect model was made by self-made quantitative semi-transected blade in the experimental group, and by ophthalmic scalpel in the control group. Then, the complications were observed; the electrophysiological results were detected before modeling and at 21 days after modeling; the histological changes at margin of lump defect were observed at 6 hours, 5 days, and 28 days; Basso, Beattie, and Bresnahan (BBB) scores were detected at 1, 3, 5, 7, 14, 21, 28, 35, 42, 56, and 84 days after modeling.

There was significant difference in the mortality between the experimental group (0) and the control group (26.67%) (P = 0.028). Electrophysiological examination: there was no significant difference in latency and amplitude of motor evoked potentials (MEP) and sensory evoked potentials (SEP) between 2 groups at preoperation (P > 0.05); at 21 days after operation, latencies of MEP and SEP increased and the amplitude decreased in the control group, showing significant differences when compared with those in the experimental group and the preoperative values (P < 0.05), but no significant difference was seen between preoperation and postoperation in the experimental group (P > 0.05). Histological examination: in the control group, small hematoma could be observed at normal side at 6 hours after modeling, increased spaces of spinal tissue and perineural invasion were observed at 5 days, and small cavity formed without normal motoneurons at 28 days in the margin of lump defect. In the experimental group, no small hematoma could be observed at 6 hours after modeling, no inreversible injury of neuron and small cavity were observed at 5 days, and normal motoneurons were observed without small cavity at 28 days in the margin of lump defect. BBB scores: except the scores between experimental group and control group at affected side (P > 0.05), there were significant differences between groups, and between normal side and affected side for intragroup (P < 0.05).

Semi-transected and lump defect model could be set up successfully by self-made quantitate semi-transected blade, procedure is repetitive and the model is stable. This model is an ideal model for semi-transected spinal cord injury.