Violence is the main cause of thoracolumbar spine fractures. The direction of violence can be through the x, y, and z axes. The spine has six types of motion: compression, tension, and rotation in the Y axis; flexion, extension, and lateral movement in the x axis; and lateral flexion and anterior-posterior directional movement in the Z axis. There are three forces that can act on the mid-axis: compression in the axial direction, pulling in the axial direction, and movement in the cross-section. The three etiologies do not coexist, for example, axial compression and axial distraction cannot coexist. Therefore, there can be six types of injury for thoracolumbar and cervical spine fractures, respectively.
Classification.
1, Classification of thoracolumbar fractures
Simple wedge compression fracture: this is the result of an injury to the anterior spine column. The violence comes from the force of rotation along the X-axis, which causes the spine to flex forward; the posterior structures are rarely affected, and the vertebrae usually become wedge-shaped. This type of fracture does not damage the middle column and the spine retains its stability. This type of fracture is usually the result of a fall from height injury, where the foot or hip lands and the body flexes violently, producing compression of the anterior half of the vertebral body.
Stability blast fracture: This is the result of injury to the anterior and middle columns of the spine. The violence comes from axial compression of the Y-axis. Usually, it is also a fall injury, the foot and hip landing, the spine remains vertical, the vertebral body of the thoracolumbar segment of the spine is subjected to the greatest force and shattered due to compression, as there is no rotational force, the posterior column of the spine is not affected, thus still retaining the stability of the spine, but the broken vertebral body and disc can protrude in front of the subvertebral canal, injuring the spinal cord and producing neurological symptoms.
Unstable blast fracture: This is the result of simultaneous injury to the anterior, middle, and posterior columns. Violence comes from axial compression in the Y-axis as well as clockwise or counterclockwise rotation and possibly rotational forces along the Z-axis are involved, causing the posterior column to fracture as well. Post-traumatic kyphosis and progressive neurological symptoms may occur as a result of spinal instability.
Chance fracture: A horizontal laceration injury of the vertebral body. Previously, it was thought that the violence came from the greatest forces rotating along the x-axis, causing injury to the spine by hyperextension. For example, a fall from a height with the back blocked by an object when landing causes hyperextension of the spine, rupture of the anterior longitudinal ligament, transverse splitting of the vertebral body, and rupture of the spinous processes by extrusion of each other, which can occur when the last vertebral body is displaced backwards. It is now thought that this is a consequence of flexion of the spine, with the axis of flexion being anterior to the anterior longitudinal ligament, and is therefore thought to be the result of axial pulling of the spine from the Y axis, with the involvement of rotational forces along the X axis. These fractures are also unstable fractures and are relatively uncommon clinically.
Flexion-distraction type of injury: The flexion axis is posterior to the anterior longitudinal ligament. The anterior portion of the column is injured by compression forces, while the middle and posterior columns are injured by tension forces of distraction; the middle portion of the column is injured to form a rupture of the posterior longitudinal ligament; the posterior portion of the column is injured by rupture of the vertebral capsule, dislocation of the articular eminence, subluxation, or fracture. This injury often also involves rotational forces from the Y-axis, so these injuries are often potentially unstable fractures due to tears in the ligamentum flavum, interspinous ligament, and supraspinous ligament.
Spinal fracture dislocation: also known as a mobility injury. The violence comes from the Z-axis, such as a car accident where the violence comes directly from the back of the back; or a heavy overhead fall that strikes the back directly while working bent over. Under strong violence, the alignment of the vertebral canal has been completely destroyed, and in the plane of injury, the spine is displaced along the transverse plane. Usually all three columns are destroyed by shear forces. The plane of injury is usually through the intervertebral disc, and there are also rotational forces involved, so the degree of dislocation is heavier than a fracture. When the articular eminence is completely dislocated, the inferior articular eminence moves anterior to the superior articular eminence of the next vertebra, blocking each other, called articular eminence interlock. This type of injury is extremely serious, spinal cord injury is inevitable, and the prognosis is poor.
There are also simple accessory fractures such as vertebral plate fractures with transverse process fractures; they do not produce instability of the spine and are called stable fractures. In particular, transverse process fractures are often avulsion fractures produced by violent contraction of the lumbar muscles after an impact on the back.
2.Classification of cervical spine fracture
Flexion-type injury: This is the result of compression in the anterior column and distraction injury in the posterior column. The violence is via the sagittal plane of the Z-axis, producing a simple soft tissue, or simple bone, or a mixed injury. Clinically common are: anterior subluxation (hyperflexion type sprain): this is the result of rupture of the posterior spinal column ligaments, both complete and incomplete. Complete ones have tears of the supraspinous and interspinous ligaments and even the spinal joint capsule and transverse ligaments, while incomplete ones have only supraspinous and partial interspinous ligament tears. This injury can have a 30% to 50% incidence of delayed spinal deformity and tetraplegia, making it an insidious type of cervical spine injury.
Bilateral vertebral interrogative joint subluxation: violence due to rupture of the posterior and middle column ligaments after hyperflexion causes the subluxed vertebral articular eminence to transcend to the front and above the next segmental tubercle. The degree of vertebral dislocation must exceed at least 1/2 of the anterior-posterior diameter of the vertebral body, and the inferior articular eminence of the dislocated vertebral body is displaced anterior to the superior articular eminence of the next segment. Some cases may have small articular eminence fractures, but the fracture fragments are generally small and of little clinical significance, and most cases in this category have spinal cord injury.
Simple wedge (compression) fracture: more common. x-ray lateral film is the anterior edge of the vertebral body cortical insertion into the angle, or the upper edge of the vertebral body end plate rupture compression, this condition is most often seen in osteoporotic patients. Pathological changes in addition to vertebral fractures, there are varying degrees of posterior ligamentous structure rupture.
Injuries due to vertical compression: violence is transmitted via the Y axis without hyperflexion or hyperextension forces such as falling objects or diving from a height.
Bilateral anterior and posterior arch fractures of the first cervical vertebra: Also known as Jefferson fractures, fracture lines are difficult to detect on x-ray, and sometimes the C. articular eminence is displaced outward bilaterally on orthopantomographs, and widening of the anterior and posterior atlantoaxial diameter and prevertebral soft tissue swelling are seen on lateral views. MRI can only show damage to the spinal cord.
The incidence of paralysis can be as high as 80% because of the varying degrees of convexity of the fracture fragments into the spinal canal, and can also be combined with craniocerebral injury.
Hyperextension injury hyperextension dislocation: most often occurs when driving a car at high speed, due to emergency braking or crashing, due to inertia, the head hits the windshield or the backrest of the seat in front and forces the head to hyperextend, followed by hyperflexion, causing serious injury to the cervical spine. The pathological changes are rupture of the anterior longitudinal ligament, horizontal rupture of the intervertebral disc, avulsion fracture of the anterior lower edge of the upper vertebral body and rupture of the posterior longitudinal ligament. As a result of the injury, the cervical spine moves backward and has kyphosis, causing injury around the central canal of the spinal cord by entrapping the spinal cord between the crumpled ligamentum flavum and the vertebral plate. In some cases, particularly in the elderly, pre-existing posterior lower cervical spines can impinged on the spinal cord, causing the plane of the damaged spinal cord to be out of alignment with the plane of the fracture. The characteristic sign of this disease is signs of trauma to the frontal face.
Injurious pivotal arch fracture: The violence of this type of injury comes from the chin, causing hyperextension of the cervical spine, creating a strong shear force in the posterior half of the pivotal spine, which overwhelms the arch of the pivotal spine and causes a vertical fracture. In the past, it was mostly seen in hanged people, so it was also known as hanged person fracture. Currently, they occur in traffic accidents on highways.
Fracture of the dentate process: The mechanism of the dentate process fracture is not well understood. There may also be several types of compound violence. Dentate fractures can be divided into three types: type 1, avulsion fracture of the tip of the dentate; type 2, transverse fracture of the base of the dentate, above the body of the pivot; and type 3, fracture of the upper part of the body of the pivot, involving the superior articular process of the pivot, either unilaterally or bilaterally. Type 1 is more stable, has fewer complications, and has a better prognosis; type 2 is more common and requires surgery because of the poor blood supply and the non-healing rate can be as high as 70%; type 3 has good stability, good blood supply, high healing rate, and a better prognosis.