[Study of injury mechanism for sacral plexus injury resulting from zone-II sacral fractures].

OBJECTIVE

To study the mechanism of sacral plexus injury resulting from zone-II sacral fractures by axial compression.

METHODS

Six short-term embalmed pelves were obtained with preserving sacral plexus and resected pubic symphysis. A model of zone-II sacral fractures by axial compression was established. Quantitative analysis for fracture displacement was carried out to observe the characteristics and mechanisms of sacral plexus injury. The experimental data were analyzed by SPSS 10.0 statistic software.

RESULTS

In the sacral fracture model of axial compression, the sacral plexus nerves of L5 and S1 were obviously compressed. The sharp border of fracture segment stabbed the nerves as the distal segment of fractures was displaced to superior-anteriorly. When the displacement exceeded 1 cm, the tension injury of sacral plexus nerves became noticeable, especially at L5, S1 and S2. There was no sacral nerve injury when the distal segment of fractures was displaced posteriorly.

CONCLUSION

The mechanisms of sacral plexus injury are complicated. And it probably have close correlations with stability, orientation, extent and duration of fracture displacement.