Abstract: Objective　To provide the anatomical basis of a new double- threaded pedicle screw for reducing the incidence of nerve root injury, by measuring the anatomical parameters of thoracic and lumbar vertebrae.　Methods　Two hundred healthy volunteers were included for the thoracic and lumbar spine CT scan. The following parameters were measured on CT films: the segment lengths of pedicle screw entry path (the length of the vertebral body, the pedicle and the lamina), the height of the pedicle isthmus, the pedicle isthmus and the angle of the screw abduction. The mean and standard deviation of each parameter were calculated.　Results　A total of 100 thoracic volunteers with an average age of 31.21 years old and 100 lumbar volunteers with an average age of 31.05 years old were included.  Parameters of the thoracic group were as follows: the length of the vertebral body was left (19.09±2.36)mm, right (19.77±2.54) mm, the length of the pedicle was left (7.67±1.19)mm, right (8.17±1.16)mm, the length of the lamina was left (9.94±2.02)mm, right (9.06±1.71)mm, the height of the pedicle isthmus was left (11.76±1.86)mm, right (11.79±2.24)mm, the width of the pedicle isthmus was left (8.44±2.71)mm, right (5.95±1.16)mm, the angle of the screw abduction was left (8.61±2.57)°, right (8.44±2.71)°. Parameters of the lumber group were as follows: the length of the vertebral body was left (26.99±3.37)mm, right (27.06±3.24)mm, the length of the pedicle was left (10.00±1.58)mm, right (10.37±1.53)mm, the length of the lamina was left (12.74±2.16)mm, right (13.96±2.46)mm, the height of the pedicle isthmus was left (14.50±2.83)mm, right (14.05±2.39)mm, the width of the pedicle isthmus was left (9.72±1.59)mm, right (9.45±1.8)mm, the angle of the screw abduction was left(16.16±2.93)°, right (16.31±3.05)°.There was no statistical differences on the length of the vertebral body, pedicle, lamina and the angle of the screw abduction between the thoracic and the lumbar groups at the same segment (P>0.05).There were statistical differences on the pedicle isthmus height from T1 to L5 and pedicle isthmus width between the two groups (P<0.05).　Conclusions　Detailed anatomical measurements of the thoracic and lumbar vertebrae in healthy subjects can provide more accurate basis for the design of a new double-threaded pedicle screw.

Key words: Thoracic vertebra, 　Lumbar vertebra, 　Anatomical measurement, 　Double-threaded pedicle screw