Objective： To explore the advantages and indications of the paraspinal approach by anatomical study and clinical application.Methods： The anatomical data and clinical practice of 27 cases were analyzed to explore the accurate approach between the paraspinal muscles and the structure of ambient tissues, as well as the results of clinical application of paraspinal approach. The operation time, blood loss, incision length, radiographic result （Cobb angle, height of anterior edge of the vertebrae） were compared with those in 24cases treated by traditional approach.Results： Complete exposure of the facets could be easily performed by identifying natural cleavage plane between the multifidus and Iongissimus muscles. The natural muscular cleavage was （1.47±0.23） cm lateral to the midline for females, and （1.64±0.35） cm for males at T12 level. The distance was （3.3±0.6） cm lateral to the midline for females,and （3.7±1.0） cm for males at L4 level. In paraspinal approach group, the operation time was （76.2±15.7） min, blood loss was （91.6±16.9） ml and incision length was （7.6±0.8） cm. In traditional approach group, the operation time was （121.4±19.6） min, blood loss was （218.7±32.3 ） ml and incision length was （17.4±2.1） cm. To compare paraspinal approach with traditional approach, the operation time, blood loss and incision length had statistical difference （P〈0.05） and the radiographic result （Cobb angle, height of anterior edge of the vertebrae） had no statistical difference （P〉0.05）.Conclusions： When the paraspinal approach is performed through natural cleavage plane between the multifidus and longissimus muscles, there are no wide muscular disinsertions, leaving the supraspinous and interspinous ligaments intact. The distance of natural cleavage to the midline is different at T12 and L4 planes. By this approach,the facet joints can be explored easily and completely, and a clear surgical field will be available for the placement of pedicle scr
JIANG Rui WU Han WANG Jin-cheng LI Wen-xuan WANG Yang
Objective： To evaluate the accuracy of computer-assisted pedicle screw installation and its clinical benefit as compared with conventional pedicle screw installation techniques. Methods： Total 176 thoracic pedicle screws placed in 42 thoracic fracture patients were involved in the study randomly, 20 patients under conventional fluoroscopic control （84 screws） and 22 patients had screw insertion under three dimensional （3D） computer-assisted navigation （92 screws）. The 2 groups were compared for accuracy of screw placement, time for screw insertion by postoperative thincut CT scans and statistical analysis by χ^2 test. The cortical perforations were then graded by 2-mm increments： Grade Ⅰ （good, no cortical perforation）, Grade Ⅱ （screw outside the pedicle 〈2 mm）, Grade Ⅲ （screw outside the pedicle 〉2 mm）. Results： In computer assisted group, 88 （95.65%） were Grade Ⅰ （good）, 4 （4.35%） were Grade Ⅱ （〈2mm）, no Grade Ⅲ （〉2 mm） violations. In conventional group, there were 14 cortical violations （16.67%）, 70 （83.33%） were Grade Ⅰ （good）, Ⅱ （13.1%） were Grade Ⅱ （〈2 mm）, and 3 （3,57%） were Grade Ⅲ （〉2 mm） violations （P〈0.001）. The number （19.57%） of upper thoracic pedicle screws （ T1-T4 ） inserted under 3D computer-assisted navigation was significantly higher than that （3.57%） by conventional fluoroscopic control （P〈0.001）. Average screw insertion time in conventional group was （4.56 ±1.03） min and （2.54 ± 0.63） min in computer assisted group （P〈0.001）. In the conventional group, one patient had pleura injury and one had a minor dura violation. Conclusions： This study provides further evidence that 3D computer-assisted navigation placement ofpedicle screws can increase accuracy, reduce surgical time, and be performed safely and effectively at all levels of the thoracic spine, particularly upper thoracic spine.
