• Hisanori Gamada, Masao Koda, Itsuo Shina, Tomoyuki Asada, Fumihiko Eto, Mamoru Kono, Yosuke Shibao, Kentaro Mataki, Kousei Miura, Hiroshi Noguchi, Hiroshi Takahashi, Toru Funayama, Tetsuya Abe, and Masashi Yamazaki.
• Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; Department of Orthopaedic Surgery, Moriya Daiichi General Hospital, Moriya, Japan. Electronic address: hisanorigamada@gmail.com.
• World Neurosurg. 2021 Jul 1; 151: e972-e978.

BackgroundThe penetrating end plate screw (PES) technique improved the fixation strength of the pedicle screw by penetrating the end plate in posterior fusion. The "double" PES, which is a trajectory that penetrates both the upper end plate of the corresponding vertebra and the lower end plate of the upper adjacent vertebral body, provides a stronger tricortical fixation but requires a stricter trajectory. The purpose of this study was to measure the cephalad angles from T7-L5 that would allow a safe trajectory for "double" PES.MethodsWe analyzed 1078 pedicles of 539 vertebral bodies of 50 consecutive cases (27 males and 23 females, mean age, 63.3 years) who underwent computed tomography (CT) myelography for evaluation of spinal disorders. The mean cephalad angle to obtain the double PES trajectory of each vertebra was examined, except for cases in which the appropriate trajectory would perforate the pedicles.ResultsThe cephalad angle for the appropriate trajectory of "double" PES ranged from 23.4 to 37.6 degrees in the thoracic spine and 34.8 to 40.8 degrees in the lumbar spine. The ratio of pedicle perforation was significantly higher at T7 (16%), L4 (26%), and L5 (52%).ConclusionsIt is important to measure the optimal cephalad angle by preoperative computed tomography imaging according to the vertebral level. In L4 and L5, "double" PES should be avoided because it is often unsafe.Copyright © 2021 Elsevier Inc. All rights reserved.

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