BackgroundCervical pedicle screw (CPS) insertion is a technically demanding procedure. The quantitative understanding of cervical pedicle morphology, especially the narrowest part of cervical pedicle or isthmus, would minimize the risk of catastrophic damage to surrounding neurovascular structures and improve surgical outcome. The aim of this study was to investigate morphology and quantify cortical thickness of the cervical isthmus by using Multi-detector Computerized Tomography (MD-CT) scan.MethodsThe cervical CT scans were performed in 74 patients (37 males and 37 females) with 1-mm slice thickness and then retro-reconstructed into sagittal and coronal planes to measure various cervical parameters as follows: outer pedicle width (OPW), inner pedicle width (IPW), outer pedicle height (OPH), inner pedicle height (IPH), pedicle cortical thickness, pedicle sagittal angle (PSA), and pedicle transverse angle (PTA).ResultsTotal numbers of 740 pedicles were measured in this present study. The mean OPW and IPW significantly increased from C3 to C7 while the mean OPH and IPH of those showed non-significant difference between any measured levels. The medial-lateral cortical thickness was significantly smaller than the superior-inferior one. PTA in the upper cervical spine was significantly wider than the lower ones. The PSA changed from upward inclination at upper cervical spine to the downward inclination at lower cervical spine.ConclusionsThis study has demonstrated that cervical vertebra has relatively small and narrow inner pedicle canal with thick outer pedicle cortex and also shows a variable in pedicle width and inconsistent transverse angle. To enhance the safety of CPS insertion, the entry point and trajectories should be determined individually by using preoperative MD-CT scan and the inner pedicle width should be a key parameter to determine the screw dimensions.

The acetabular labrum is the connective tissue between femoral head and hip joint that acts like a shock absorber. Labral injury could happen after hip dislocation or internal derangement such as femeroacetabular impingement (FAI) syndrome. The surgeon usually attempts to repair or reconstruct the torn labrum to obtain the native hip biomechanical loading. There has been no scientific evidence study for the different surgical techniques. Hip simulation machine was made to let a femur move in six conditions including flexion, extension, abduction, adduction, internal rotation and external rotation. The hip was compressed with a force of half of the body weight (350 N). The purpose of this study was to study pressurization in three labral conditions including intact labrum, labral repair and labral reconstruction. The machine was designed and simulated by SolidWorks software. A device's controller had two mode including a manual mode to set zero before an operation and automation mode to move in six conditions and compressed with a force of body weight. After the construction, the machine was tasted by using counterfeit pelvis and femur. The device was reformed before a real taste. Dissected cadaveric pelvises were used and measured pressure through the film piezoresistive load sensors. The testing result was helped the surgeon to make a decision in surgery process.

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The secondary curve (S-shape) is one of the scoliosis deformity types. Scoliosis usually occurs in the thoracolumbar region of the adolescents, adulthood and the elderly. If the patient is not advised and treated by the surgeon, the patient will be in more pain and the curvature of scoliosis will be increased. The screw fixation system or pedicle screw system is popular in the treatment of spinal deformity. Because the surgical treatment is highly considered as successful, the postoperative of the pedicle screw system will become virtual homogeneous vertebral and movement together; however, there are few studies reporting the post-operative results in Thai scoliosis surgery. Therefore, this study aims to analyse the strain of Thai scoliosis (S-shape) as compared with normal Thai spine and Thai scoliosis adjusted by screw fixation system under the compressive load with a finite element method. The results showed the maximum strain occurred on Thai scoliosis, normal Thai spine and Thai scoliosis adjusted by screw fixation system respectively. It appeared that the strain occurred on the model of scoliosis adjusted by screw fixation system were more decreased/reduced than the scoliosis model and it is reasonable if compared with the normal model, due to the pedicle screw fixation system could be absorbed the strain occurred on the spinal very well. The center of scoliosis pre-operative was at T7 and L1 levels which had the maximum displacement before being adjusted by screw fixation system. It affects the strain occurred on the models by the reaction force. As mentioned above, the patient should be advised and treated by the surgeon as quick as possible in order to return to daily activities better than before the surgery.

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