Advantages of the paraspinal muscle splitting approach in comparison with conventional midline approach for s1 pedicle screw placement.
METHODS
A retrospective comparative study of the S1 pedicle screw (S1PS) position obtained using 2 surgical approaches.


OBJECTIVE
To determine whether the paraspinal approach leads to more medially oriented placement of the S1PS compared with the midline approach.


BACKGROUND
To obtain a stronger as well as safer fixation of the S1PS, medially oriented screw placement is very important. However, no study has recommended a surgical approach to achieve this object.


METHODS
The positions of 32 screws placed by the midline approach and 34 screws placed by the paraspinal approach were compared using postoperative computed tomography. The location of the bilateral common iliac veins (CIV) in relation to the S1PS tips was also analyzed to evaluate their safety.


RESULTS
There was no statistical difference in screw insertion point regardless of the approach employed. However, in the paraspinal group the S1PS were placed with significantly greater medial direction and with longer screws. In addition, they pierced the anterior sacral cortex closer to the midline compared with the midline approach. Four left screws in the midline approach group made contact with the left CIV, whereas no screw in the paraspinal approach group lay adjacent to the CIV.


CONCLUSIONS
Our results demonstrate that the paraspinal approach for S1PS placement may be superior to the midline approach in terms of the medially oriented screw placement that is biomechanically stronger and less risky for the CIV.
Ota
Masato
M
Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, Japan. otamasa@kuhp.kyoto-u.ac.jp
Neo
Masashi
M
Fujibayashi
Shunsuke
S
Takemoto
Mitsuru
M
Nakamura
Takashi
T
D000328:Adult; D000368:Aged; D001863:Bone Screws; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012447:Sacrum / Q000000981:diagnostic imaging / Q000601:surgery*; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D018709:Statistics, Nonparametric