A vertebral compression fracture (VCF) occurs when one of the bones of the spine, called a vertebra, collapses under pressure. This injury causes the bone to lose height, typically affecting the front part of the vertebral body. X-rays are the initial tool used by medical professionals to identify this specific type of spinal collapse.
Understanding Vertebral Compression Fractures
A vertebral compression fracture involves the structural failure of the vertebral body, the thick, cylindrical segment of bone that forms the front part of the spine. When the body collapses, it often results in a wedge-shaped deformity, which can lead to spinal curvature and pain. These fractures are most commonly found in the middle and lower back, specifically at the thoracolumbar junction.
The mechanism of injury varies widely, ranging from high-energy trauma, such as a car accident, to minimal stress in vulnerable patients. For younger, healthy individuals, a VCF typically requires significant force or an extreme vertical shock. However, the most frequent cause, especially in older adults, is the gradual weakening of bones due to osteoporosis.
When bone density is significantly reduced due to osteoporosis, vertebrae can fracture from routine activities like bending, coughing, or lifting a light object. This weakening eventually causes the bone to flatten, resulting in a compression fracture. Other less common causes include metastatic tumors that weaken the bone structure or specific medical conditions.
The Role of X-Rays in Initial Diagnosis
X-rays are the initial imaging choice when a vertebral compression fracture is suspected. They quickly identify a change in the shape of the vertebrae. This method is widely accessible, relatively low-cost, and provides immediate results, which is valuable in an acute care setting.
The standard procedure involves taking at least two views of the spine: a lateral view and an anteroposterior view. The lateral view is the most informative for VCFs because it clearly shows the height and shape of the vertebral bodies. The anteroposterior view helps the physician assess the alignment of the spine and look for other structural issues.
While X-rays are excellent for confirming the presence of a fracture and its morphology, they have limitations. They cannot easily distinguish between a benign fracture caused by osteoporosis and a pathological fracture caused by a tumor. Furthermore, X-rays alone often cannot determine the age of the fracture, which is an important consideration for treatment planning.
Interpreting the X-Ray Image
A compression fracture creates a characteristic appearance on a lateral X-ray. The most common finding is a “wedge deformity,” where the front of the vertebral body has collapsed, causing it to look shorter than the back and giving the vertebra a trapezoidal or triangular shape.
The severity of the fracture is measured by quantifying the loss of vertebral height compared to an adjacent, unfractured vertebra. A diagnosis is typically made when the height of the affected vertebra has decreased by at least 20% or by a minimum of 4 millimeters. This measurement is usually taken at the anterior edge of the vertebral body, as this is the area that fails under compression.
Physicians may use classification systems, such as the Genant semiquantitative grading system, to standardize the assessment of the fracture. This system categorizes severity based on the percentage of height loss: mild (20% to 25%), moderate (25% to 40%), and severe (greater than 40%). The X-ray is also examined for any angular deformity, or kyphosis, which is an excessive forward curvature of the spine.
Next Steps After Diagnosis
Once an X-ray confirms a vertebral compression fracture, the next steps focus on determining the fracture’s acuity and planning management. X-rays often cannot determine if the fracture is acute (new) or chronic (old). This distinction is crucial because acute fractures are generally the source of current pain and may be candidates for certain interventions.
To determine the age of the fracture and check for other issues, follow-up imaging is often necessary. A Magnetic Resonance Imaging (MRI) scan is frequently used to look for bone marrow edema, which is swelling that confirms a fracture is recent and active. A Computed Tomography (CT) scan provides a more detailed, three-dimensional view of the bone structure, which is helpful for assessing the extent of the fracture and ruling out involvement of the posterior spinal column or nerve impingement.
The treatment plan then proceeds along two main pathways: conservative management or intervention. Conservative care, which is the initial approach for most stable fractures, involves rest, pain medication, and sometimes a back brace to provide external support and limit motion. If pain remains significant after weeks of conservative treatment, more invasive options may be considered, such as vertebroplasty or kyphoplasty, which involve injecting bone cement into the collapsed vertebra to stabilize it.