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.

No abstract