. 2016 Feb 5;7(2):101–108. doi: 10.1016/j.jcot.2015.12.002

Table 3.

Tabulated various studies from the literature studied on thoracic or lumbar pedicles to decide on the novelty of idea of the present study.

Study	Important observations and conclusions of the study
Zindrick et al., 1987^¹⁴	Pedicle dimensions and angles change throughout the spine. A detailed knowledge of these relationships is important for any surgeon contemplating the use of the pedicle for screws purchase to prevent screw cutout and failure of fixation or neurologic injury.
Kim et al., 1994^²¹	The results suggest that using 6-mm screws can violate the cortex of the pedicles in a significant number of levels of the upper lumbar spine. Using a screw longer than 40 mm is dangerous in the lower thoracic spine of a Korean.
Vaccaro et al., 1995^²⁴	The precise morphology of the individual patient's vertebrae must be determined with the use of pre-operative computerized tomographic scans to define three important variables: the angle of insertion of the pedicle into the vertebral body, the transverse diameter of the pedicle, and the cord length.
Ebraheim et al., 1997^¹¹	This information, in conjunction with preoperative computed tomography evaluation, may enhance our knowledge of transpedicular screw fixation in the thoracic pedicle.
Cinotti et al., 1999^¹⁰	Pedicles between T4 and T8 may not be wide enough for screw fixation.
Ugur et al., 2001^¹³	The following suggestions are made based on the results. (1) More care should be taken when a transpedicular screw is placed in horizontal plane. (2) Improper medial placement of the pedicle screw, especially in the middle thoracic spine, should be avoided, and the anatomic variations between individuals should be considered. (3) Because of substantial variations in the size of thoracic pedicles, utmost attention should be given to the findings of a computed tomographic evaluation before thoracic transpedicular fixation is begun.
McLain et al., 2002^²³	Even the largest patient had some pedicles that could not accommodate the smallest standard pedicle screws, and more than half of the pedicles average patients were too small.
Chadha et al., 2003^²⁷	It is suggested that preoperative computed tomography scans of the patients must be evaluated to choose the appropriately sized implant and avoid inadvertent complications. Preparation of the pedicle intraoperatively should take into account the orientation of the transverse pedicle angle.
Datir and Mitra 2004^²⁶	The results suggest that even a 4-mm screw should be used carefully at the midthoracic level; 5-mm screw seems to be safe at upper and lower thoracic spine. Because of very small sagittal and transverse angles at mid and lower thoracic levels, the pedicular screws should be inserted along perpendicular line in these planes; 25-mm and 30-mm screw length appears to be safe at upper thoracic and lower thoracic levels, respectively.
Tan et al., 2004^¹⁷	Compared to the Caucasian data, all the dimensions were found to be smaller. Of significance were the spinal canal area, and pedicle width and length, which were smaller by 31.7%, 25.7% and 22.1% on average, respectively.
Christodoulou et al., 2005^²⁸	Pedicle dimensions at the levels from T3 to T8 need preoperative evaluation with computed tomography before the insertion of pedicle screws with diameter more than 5 mm. Pedicles at T12 to L5 levels may accommodate screws of 7 mm diameter.
Liau et al., 2006^²⁹	The safe level for transpedicular fixation using 4.5-mm screw appears to be at T1, T2, T11, and T12. However, even at these levels, up to 20% of female patients and up to 6.7% of male patients have pedicle diameter of less than 5.5 mm. Safe screw length was between 30 mm and 35 mm. A 40-mm screw would be too long for thoracic spines in this population.
Pai et al., 2010^⁸	Knowledge of the pedicle diameter and chord length is essential for choosing the appropriate pedicle screw, whereas the pedicle angle and the entry point are important for accurate screw placement.
Acharya et al., 2010^³⁰	Significant differences exist between the pedicles of Indian and white populations. It is suggested that preoperative software-based morphometric data should be collected if possible for preoperative planning of pedicle implant placement and sizes to avoid inadvertent complications.
Singh et al., 2011^¹	The smallest diameter screw and shortest available screw for adults are not safe in majority of the Indian population in mid-thoracic region. The results of the present study can help in designing implants and instrumentations; understanding spine pathologies; and management of spinal disorder in this part of the world.
Shetty et al., 2011^³⁸	These results show that 5 mm screw should be safe at upper and lower thoracic spine; 26–28 mm screw length appears to be safe at upper and lower thoracic level. Even 4 mm diameter screw was used with care in mid thoracic region. Because of the smaller pedicle size and more proximity to the spinal cord and the neurovascular structure, the pedicle screw fixation is difficult. Hence, precise knowledge of the pedicular dimension and pedicular entrance point is essential for thoracic pedicular screw fixation.
Kretzer et al., 2011^³³	Preoperative CT evaluation is important in choosing PS length, diameter, trajectory, and entry point due to variation based on spinal level, patient sex, and side of placement. These data are valuable for resident and fellow training to guide the safe use of thoracic PSs.
Biscevic et al., 2012^³⁰	For accurate performing of transpedicular screws, knowledge of anatomical and radiological characteristics of spine is essential.
Avuthu et al., 2014^³⁹	Pre-operative computed scan is recommended to choose an appropriately sized implant and avoid complications.