RESUMEN
Objective To construct a three-dimensional (3D) lumbar spine model to allow real-time complicated interactions in virtual lumbar surgery based on virtual reality technique. Methods The data of high-resolution CT slices were segmented and the contours were extracted. Surface rendering technique was adopted to construct of the lumbar spine model on the basis of serial contours, and the model was optimized according to the need of real-time interaction. Results The lumbar spine model with fewer polygons was characterized by high resolution and smoothness. After being loaded in the virtual surgery system, the model accurately displayed the anatomy of lumbar spine and allowed real-time interaction during the virtual surgery. Conclusion The 3D lumbar spine model constructed based on the CT slices is applicable for complicated interactions in virtual lumbar surgery.
RESUMEN
The mechanics of a new shape memory alloy cervical hook for atlantoaxial instability was analyzed with finite element method on the basis of a three-dimensional model reconstructed from the images of CT scanning of an adult cadaveric upper cervical at 1-mm interval. The stress and displacement of every nodule and element in the course of deformation of the internal fixation were tested, and the results showed that the cervical hook was strong enough against tensile stress, which concentrates in the middle of the device. The pull was 237.58 N at the loading point. With such mechanical performance, this cervical hook can be reliable for correction of atlantoaxial instability.