Objective      To compare the biomechanical properties of the anterior osteotomy of pedicle (AP) and posterior osteotomy of pedicle (PP) by finite element analysis

and to explore the effects of the pedicle-lengthening osteotomy site on lumbar stability.        Methods      CT images were obtained from a 28-year-old female volunteer

and then the inta

ct L

2

-L

5

AP

and PP models were established and analyzed with Mimics 14.0

Geomagic Studio 2013

and ANSYS 14.0 software. The axial force of 400 N and moment couple of 10 N·m were loaded on the upper surface of L

2

to simulate the flexion

extension

lateral bending

and rotation behaviors of the lumbar spine. The Von Mises stress distribution regularity of internal fixators and the maximum equivalent stress were evaluated

and the range of motion (ROM) were also analyzed.        Results      The intact model of lumbar spine (L

2

-L

5

) was established

and it was validated with the previously reported cadaveric experimental data from Yamamoto and Liu successfully. The stress was concentrated at the connection portion between plate and screw in the AP group

while it was distributed evenly in the PP group. Between the AP group and the PP group

there was significant difference in stress values under flexion

lateral bending and rotation conditions. Compared with the intact group

the change scope of ROM of L

4

-L

5

segment and L

3

-L

4

segment in the PP group was smaller than that in the AP group

and there was no significant difference in the ROM of L

2

-L

3

segment between the two groups. Compared with the intact model

the whole ROM of the lumbar spine increased about 1°  in the AP group and the PP group.        Conclusion      As a new alternative method

PP provides better stability and lower influence on adjacent segment than AP.