Objective      To investigate the role of the posterior different structures in the stability of the thoracic spine.       Methods      The thoracic spine specimen of T

7

to T

10

consisting of the sixth to ninth ribs

were collected from 9 fresh cadavers. After the intact specimen was tested

the specimen of T

8

to T

9

received the following procedures in turn

total unilateral facetectomy with unilateral laminectomy

resectio

n of unilateral costoverebral joint

resection of the posterior ligamentous complex with laminectomy

bilateral total facetectomy

and resection of the bilateral costoverebral joints. Biomechanic tests were carried out in all groups of specimens

Multidirectional flexibility of each specimen was measured in flexion-extension

right/left lateral bending

and axial rotation under a loading of 5 N·m for their range of motion (ROM). Paired student’s t-test was used to analyze the ROM of the specimens in intact and after different resection.       Results      There was no significant difference in ROM of above motions in the intact cadaveric thoracic spines and those after total unilateral facentectomy with unilateral laminectomy (P0.05)

however

ROM was significantly increased in the specimens after bilateral total facetectomy (P0.05). And obvious difference was observed in ROM of flexion-extension and axial rotation in the specimens after resection of the posterior ligamentous complex with laminectomy (P0.01). A significant increase in ROM of all above motions was observed in the specimens after bilateral resection of the costovertebral joints (P0.01).       Conclusion      In cadaveric thoracic spines

the facet joints play important role in the stability of flexion-extension and axial rotation

but total unilateral facentectomy with unilateral laminectomy did not significantly increase the ROM. The state of the posterior ligamentous complex exerts a control effect on the stability of the thoracic spine in flexion-extension. The costovertebral joints are one of the most important stabilizing structures to the thoracic spine in the sagittal

coronal

and transverse planes.