A vertebral compression fracture occurs when one of the bones in your spinal column, a vertebra, collapses or breaks. These fractures are frequently observed in the thoracic, or middle, section of the spine. Common causes include weakened bones due to osteoporosis, trauma like falls, or underlying medical conditions such as tumors. When a compression fracture is suspected, an X-ray is typically the initial imaging tool for diagnosis.
The Diagnostic X-ray Procedure
Undergoing an X-ray for a suspected compression fracture is a quick, non-invasive, and painless procedure. Patients are commonly asked to stand or lie on an examination table. To obtain a comprehensive view of the spinal alignment and bone shape, at least two images are captured: an anteroposterior (AP) view from the front, and a lateral view from the side. No specific preparation is typically required.
Visual Hallmarks of a Compression Fracture
A normal vertebra on an X-ray typically appears as a rectangular or block-like structure. When a compression fracture is present, radiologists look for specific changes in this shape. The most common sign is a noticeable loss of height in the vertebral body, particularly at its front, which gives the bone a distinct “wedge shape” on the lateral X-ray view.
The extent of height loss helps classify the fracture’s severity. A mild fracture involves less than 25% height reduction, while a moderate fracture shows a 25% to 40% loss. Fractures with more than 40% height reduction are considered severe.
Different fracture patterns can also be observed: a wedge fracture involves primarily the front of the vertebra, a crush fracture indicates a more uniform collapse of the entire vertebral body, and a burst fracture shows height loss in both the front and back of the vertebral body, often with bone fragments potentially displaced into the spinal canal.
Limitations and Follow-Up Imaging
While X-rays are effective for visualizing bone structures, they have limitations, particularly in assessing soft tissues. An X-ray cannot show damage to the spinal cord, surrounding nerves, or supporting ligaments. This means that while a fracture may be visible, any associated injury to these soft tissues, which could impact neurological function, is not directly evident.
Determining the age of a compression fracture is another challenge for X-rays alone. It can be difficult to distinguish between a new (acute) fracture and an older (healed) one based solely on the X-ray image.
To overcome these limitations, a doctor may order additional imaging tests. Magnetic Resonance Imaging (MRI) is frequently used to evaluate soft tissue injuries, detect nerve compression, and identify bone marrow edema, which indicates a new fracture. A Computed Tomography (CT) scan provides a more detailed, three-dimensional view of the bone structure, especially for complex burst fractures where bone fragments may pose a risk to the spinal canal.