胸腰椎骨折的影像学-培训课件.ppt

Thoracolumbar FracturesGeneral Comments The type of injury that occurs with blunt trauma to the spine is related to the forces acting upon it at the moment of injury and may involve ?exion, extension, compression, distraction, rotation, or shear forces. In general, pure compressive or distractive forces tend to produce fractures, whereas rotatory and shear forces often result in dislocations. Most injuries of the thoracic and lumbar spine occur near the thoracolumbar junction for a variety of reasons: (1) the ribcage provides additional stability for the ?rst 9 thoracic vertebrae (2)motion is greatest in this region of the thoracolumbar spine; (3) the facet joints transition from a predominantly coronal orientation in the upper thoracic spine to a more sagittal orientation in the lumbar spine, resulting in less resistance to ?exion in the lower thoracic and lumbar regions. Thoracic spine injuries above the thoracolumbar junction are less common, but have a high incidence of associated neurologic injury. (2 reasons) Classi?cation SystemsIn 1984, Denis proposed a 3-column classi?cation system for thoracolumbar injuries. Thoracolumbar fractures were also divided into “minor” and “major” groups. Minor fractures included those involving the spinous process, transverse process, and pars intra-articularis. Major fractures were broken into 4 categories: compression, burst, ?exion-distraction, and fracture dislocation. Fracture Types1. Compression Fracture On MR images, in addition to anterior wedging, an acute compression fracture will indicate edema-like signal intensity within the marrow of the affected vertebral body. This is most conspicuous on a T2-weighted image. The absence of this type of signal within a compressed vertebra indicates an old, healed fracture. A(T1):2 thoracic fractures B(T2):pronounced edema relative to the more proximal fracture As a result, MRI can be useful in differentiating acute from chronic