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Codfish vertebra (also called biconcave vertebra) refers to a spinal vertebral body deformity where the central portion of the vertebral endplates is depressed, giving the vertebra a biconcave or fish-mouth appearance on frontal or lateral radiographs.
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Radiologic appearance:
| Feature | Description |
|---|---|
| Central endplate concavity | Symmetrical inward bowing of both superior and inferior endplates |
| Anterior and posterior heights preserved | No wedge compression deformity |
| Biconcave silhouette | Vertebra appears “caved in” in the center—resembling a codfish mouth or a flattened disc space |
Codfish vertebrae: Lateral radiograph of the lower thoracic spine showing codfish vertebrae (biconcave deformities of multiple thoracic vertebral bodies) in an 8-year-old patient affected by OI.
Pilar M, Trisolino G, Sangiorgi L, Guglielmi G, Bazzocchi A. Imaging of Congenital Skeletal Disorders. Seminars in Musculoskeletal Radiology. 2021;25(01):022-038. doi:https://doi.org/10.1055/s-0041-1723964
Common Causes of Codfish Vertebrae:
| Category | Condition |
|---|---|
| ‣ | Osteoporosis, osteomalacia |
| Endocrine disorders | Cushing syndrome, hyperparathyroidism |
| Hematologic disorders | Sickle cell anemia, thalassemia, multiple myeloma |
| Renal bone disease | ‣ in CKD |
| Congenital/others | Gaucher disease, mucopolysaccharidoses, prolonged steroid use, bed rest |
Differentiating Codfish from Other Vertebral Signs:
| Sign | Description | Common Conditions |
|---|---|---|
| Codfish vertebra | Central endplate concavity (biconcave shape) | Osteoporosis, osteomalacia |
| H-shaped vertebra | Central endplate infarction with sharp concavity | Sickle cell anemia |
| Rugger-jersey spine | Dense endplates, central lucency | Secondary hyperparathyroidism (CKD-MBD) |
| Sandwich vertebra | Dense endplates with normal center | Osteopetrosis |
| Vertebra plana | Flattened vertebral body | Langerhans cell histiocytosis, metastasis, trauma |
