Normal Thoracic Wedge Compression Fracture Size on X-Ray/CT
A thoracic wedge compression fracture occurs when the anterior vertebral body height is reduced relative to the posterior height, producing a characteristic wedge-shaped deformity on lateral imaging. Accurate measurement of this height difference is essential for distinguishing physiologic vertebral contour variation from true fracture or pathologic collapse. Quantifying the degree of wedging also guides management decisions, including the need for immobilization, surgical stabilization, or further oncologic workup.
Normal Reference Values
| Orientation | Location | Measurement |
|---|---|---|
| Lateral | Difference Between Posterior And Anterior Vertebral Height | <3 mm |
Clinical Significance
A difference of less than 3 mm between posterior and anterior vertebral body height on lateral projection is considered within normal limits. Values at or exceeding this threshold raise concern for true compression injury or underlying pathology. Progressive wedging, multilevel involvement, or posterior cortical disruption significantly increases the likelihood of instability.
When the anterior-posterior height difference exceeds the normal threshold, the following conditions should be considered:
- Acute traumatic compression fracture (axial loading mechanism)
- Osteoporotic insufficiency fracture (elderly patients, minimal trauma)
- Pathologic fracture secondary to metastatic disease or myeloma
- Scheuermann’s disease (multiple contiguous levels, endplate irregularity)
- Congenital vertebral anomaly or developmental wedging
A key pitfall is that mild physiologic wedging can be present at the thoracolumbar junction (T10–L1) and in the mid-thoracic spine, so clinical context and comparison with adjacent levels is critical. Retropulsion of posterior cortical bone into the spinal canal, best evaluated on CT or MRI, must be excluded in all acute fractures.
Reference: Benson M, Fixsen J. Children’s Orthopaedics and Fractures. Springer Verlag. (2010).
Imaging Notes
On lateral radiography, measure the anterior vertebral body height at the midpoint of the anterior cortex and compare it to the posterior body height measured along the posterior cortex at the same level. Ensure a true lateral projection to avoid rotational error that can artificially reduce apparent anterior height. A plumb-line technique or digital caliper tool on PACS is recommended for reproducibility.
On CT, reformatted sagittal images in bone window provide the most accurate height measurements and additionally reveal subtle endplate fractures, cortical disruption, and retropulsion not visible on plain films. Thin-slice sagittal reconstructions (≤1 mm) are preferred for precise anterior and posterior height quantification at the level of maximum deformity.