Compression Fractures

Compression fractures in the cervical and upper thoracic regions are most often traumatic in origin. In the middle, lower thoracic, and lumbar regions, the fractures are related to axial loading as has been seen in elderly and osteoporotic patients. Commonly the patient is an elderly

Thoracic Vertebral Compression Fracture

post-menopausal woman aged 60 or older (23). Osteoporosis is a disease characterized by low bone mass and microarchitectural deterioration of bone tissue that leads to pronounced bone fragility and increased fracture risk. The compression fracture of the osteoporotic patient can reduce vertebral height and can also cause lateral displacement of the bone. The fracture may extend into the lateral masses and posterior arch. The compression fractures of the spine often produce wedging of the vertebral body, which may also be associated with retropulsion of bone fragments and posttraumatic disc herniation. Other fracture types include burst or vertical shear fractures. Anterior to posterior dislocations may result from disruption of the anterior or posterior longitudinal ligaments.

History In most cases, the patient can recall the exact moment he or she developed symptoms. In the acute phase, the fragments may compromise nerve fibers in the central canal or foramen, causing pain that may be severe, disabling, and lasting up to 6 wk. When the pain extends beyond 6 wk this indicates poor healing, and the patients may experience a persistent dull ache. With movement the pain is aggravated and may become excruciating. Additional fractures or refracturing of the initial injury may occur (24). Fractures may result in loss of height, kyphosis, and chronic pain. In the chronic phase, bone overgrowth with remodeling into the posterior or lateral canals can compromise the lateral recesses, central canal, or foramen.

Physical Examination The patient presents with focal tenderness over the compressed vertebra. The evaluation consists of a thumb compressing the spinous process of the vertebra in the region of tenderness. Alternatively the index and third finger can palpate the tissues lateral to the spinous process in a deep or rocking motion (Fig. 8). This latter maneuver may be more specific when the patient's discomfort is too diffuse. The pain may be dull in the subacute or chronic phase.

Often the patient complains of a dull persistent ache that is acute and sharp only during activity, especially exacerbated with rising from the supine or sitting position. This can be tested by having the patient flex and extend the spine.

Mild weakness may persist for days or weeks. If the fracture compromises the cord, reflex changes from cor-ticospinal tract dysfunction can follow and include hyper-reflexia, sensory loss, loss of sphincter control, and weakness of the lower extremities. Deep tendon reflexes can be helpful in clinical assessment. Absence of deep tendon reflexes implies dysfunction at the peripheral nerve or root level. In the setting of diffuse reduction of the deep tendon reflexes, the test for Babinski's sign of upper motor neuron involvement may help determine whether there is brain or cord involvement. Stroking along the plantar surface of the foot may cause dorsiflexion of the great toe and fanning of the others (Fig. 9).

Diagnostic Imaging Plain films of the spine are an excellent first imaging technique that can reveal a collapse, fracture, or associated dislocation of the spine. Despite an unrevealing initial evaluation, repeat radiographs in 7-10 d are appropriate when a fracture is suspected because callus formation or abnormal alignment may become evident.

Changes in the matrix of bone lead to osteoporosis and increased fracture risk, which can be detected by bone mineral densitometry. The bone mineral density is a noninvasive measurement of the bone mineral content in grams per square centimeter. The bone mineral content is considered normal if it is no lower than 1 standard deviation (SD) below the mean. Bone mineral density between 1.0 and 2.5 SD below the mean indicates osteopenia or low bone mass. A bone mass and density below 2.5 SD indicates osteoporosis (25). The fracture risk increases with each SD decline in the bone mineral density.

CT scans from an axial view are helpful to assess compromise of the central canal. CT may not clearly show associated disc herniations or the impingement of the lateral recesses and foramen. However, three-dimensional reconstruction can assist in visualization of the neural foramen. CT can characterize anterior to posterior dislocations and is also the best modality for finding teardrop fracture and fractures of the cervical spine.

MRI can show the fracture line as a low signal on T1 and T2. A high signal of marrow edema can be seen on T2 images. Encroachment of the cord and effaced epidural and foramen fat can be depicted on T1 images when the normal high signal of fat is displaced. A high signal in the cord from edema or hemorrhage on T2 images has been associated with a significant cord injury. Cord compromise is uncommon in osteoporotic compression fractures.

In the hyperacute phase the radionuclide bone scan may not show any change in activity. By 24 h there should be increased activity at the fractured vertebra. A linear, horizontal fracture line is shown by radiotracer uptake. In the setting of trauma or multiple fractures the intensity of the activity differentiates the more acute fractures from the older ones.

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