BackgroundSeveral methods including free-hand technique, fluoroscopic guidance, image-guided navigation, computer-assisted surgery system, robotic platform and patient’s specific templates are being used for pedicle screw placement. These methods have screw misplacements and are not always easy to be applied. Furthermore, it is necessary to expose completely a large portions of the spine in order to access fit entirely around the vertebrae.MethodsIn this study, a multi-level patient’s specific template with medium invasiveness was proposed for pedicle screw placement in the scoliosis surgery. It helps to solve the problems related to the soft tissues removal. After a computer tomography (CT) scan of the spine, the templates were designed based on surgical considerations. Each template was manufactured using three-dimensional printing technology under a semi-flexible post processing. The templates were placed on vertebras at four points—at the base of the superior-inferior articular processes on both left–right sides. This helps to obtain less invasive and more accurate procedure as well as true-stable and easy placement in a unique position. The accuracy of screw positions was confirmed by CT scan after screw placement.ResultsThe result showed the correct alignment in pedicle screw placement. In addition, the template has been initially tested on a metal wire series Moulage (height 70 cm and material is PVC). The results demonstrated that it could be possible to implement it on a real patient.ConclusionsThe proposed template significantly reduced screw misplacements, increased stability, and decreased the sliding & the intervention invasiveness.

A method has been introduced in this paper to measure the kinematics of a knee joint and to use it as a boundary condition to model the knee's mechanical behaviour. A mobile C-Arm fluoroscopy system (Ziehm Vision R) and a CCD camera were used for the measurement of a patient's knee kinematics. The fluoroscopic images were recorded with 12 fps and then sent to Matlab software (Mathworks, Natick, MA, USA) for image processing. In parallel, CT scan images of the knee bones were used to create the 3D anatomical geometry of the knee by aid of Mimics software (Materialise NV). However, the geometrical model of the two medial and lateral menisci was generated from MRI data. The 3D geometrical model of the knee was then sent to Abaqus finite element software (Simulia Dassault Systems) to analyse the knee joint contact loads by introducing the boundary condition which was obtained from fluoroscopic images. The finite element model was used to evaluate the stress distribution on the cartilages during the gait. The result was then compared with the experimental data of gait analysis. The comparison between the results showed a close agreement between the two outcomes.

Free-hand pedicle screw placement is still conventional in surgery, although it has potentially high risks. The surgical procedures such as pedicle screw placement are usually designed based on medical imaging, but during surgery, the procedures are not normally followed due to the fact that some points are missed in two-dimensional images and seen only during surgery. In this regards, some highly accurate computer-assisted systems have been proposed and are currently used. Moreover, it is possible to reduce or completely avoid hand working by applying modern digital technology. Therefore, using these technologies has remarkable advantages. In this study, we have presented a new approach of pedicle screw placement in the lumbar and sacral regions using a specific drill guide template. The template was created by additive manufacturing technology and was verified in a clinical study as well. The main aim of this research includes the following: design, analyze, manufacture and evaluate the accuracy of a new patient-specific drill guide template, for lumbar pedicle screw placement, and compare the template to the free-hand technique under fluoroscopy supervision. Our results show that the incidence of cortex perforation is substantially reduced compared to existing methods. Finally, we believe that this approach remarkably lowers the incidence of cortex perforation and could be potentially used in clinical applications, particularly in certain selected cases.

Fluoroscopy-guided placement of pedicle screws is usually used to position pedicle screws, although it is highly risky due to lack of accuracy during operation and surgeon's intensive labor requirement during surgery. In this study, a new method was introduced to consider the issues and we tried to reduce the risk of pedicle screw placement and drilling process. To put pedicle screws in the correct position and orientation, a specific drill guide is designed and fabricated by additive manufacturing technology. In addition, since the drilling process is remarkably important and it is usually dependent on surgeon skill, therefore a teleoperation system is proposed to perform this task. In order to let the surgeon to have better control on the patient, a control scheme including position and velocity signals along with surgeon force and reaction force of vertebra was proposed. This helped the surgeon for proper control on the patient during surgery. A force estimation algorithm was presented to eliminate measuring external force signal. Consequently, 10 vertebras were used to evaluate specific drill guide and teleoperation system simultaneously. Then, the computed tomography evaluation demonstrated that Kirschner wire trajectories followed the planned axes with an error between 1 and 2 mm in 20% of cases and less than 1 mm in 80% of cases. The results obtained by the teleoperation system showed that the surgeon, in the master side, has proper control over the patient body in the slave side because the slave robot followed the master position. Furthermore, the surgeon in the master side sensed the reaction force of vertebra in the slave side appropriately.

This paper is focusing on the measurement methods of the femoral head at the hip hemiarthroplasty surgery. The measurement result of 10 femoral head specimens using four different methods of Vernier calliper, ring gauge, CT scan and X-ray were compared. It is generally believed that under sizing of the implant may cover the errors of the measurement methods, but the result of this study shows that the callipers and ring gauge measurements are more reliable than the CT and X-ray methods. Conclusively, the full-circle ring gauge or femoral head template is the recommendation for measurement of the femoral head diameter in the hip hemiarthroplasty surgery.