Rugger jersey spine | Radiology Signs

Answer:

Rugger jersey spine is a band of increased density along the superior and inferior endplate regions of multiple contiguous vertebral bodies, with a relatively lucent mid-body between them, so the spine resembles the horizontal hooped stripes of a rugby jersey. It is regarded as essentially diagnostic of secondary hyperparathyroidism, almost always in the setting of chronic kidney disease and renal osteodystrophy. The defining feature on which the differential turns is that the sclerotic bands have indistinct, blurred margins that fade gradually into the lucent centre. In sandwich vertebra of osteopetrosis, the dense endplate bands are sharply demarcated from the central bone, giving a crisp three-layer appearance. Other associated features of renal osteodystrophy should be sought: subperiosteal resorption of the radial aspects of the middle phalanges, acro-osteolysis, the salt-and-pepper skull, brown tumours, soft-tissue and vascular calcification, and Looser zones of coexisting osteomalacia.

Why is it called so?

The alternating dense and lucent horizontal bands down the spine reproduce the hooped stripes of a rugby football jersey.

Pathophysiology

Chronic renal failure causes phosphate retention, reduced calcitriol synthesis and hypocalcaemia, driving sustained parathyroid hormone excess. Raised PTH accelerates bone turnover: osteoclastic resorption is matched by vigorous osteoblastic formation of new osteoid, but that osteoid is poorly mineralised because calcitriol is deficient. The subchondral bone beneath the endplates is the most metabolically active region of the vertebra and turns over fastest, so the excess osteoid accumulates there and, by sheer increase in tissue volume, appears radiodense. Because the process is a gradient of metabolic activity rather than a structural boundary, the bands blur into the adjacent bone, which is exactly what distinguishes them from the sharply defined bands of osteopetrosis.

Alternative names: Rugger-jersey spine, rugby jersey spine

Other associated named signs: Sandwich vertebra of osteopetrosis, subperiosteal resorption, salt and pepper skull, brown tumours, and Looser zones

References

1. Chang CY, Rosenthal DI, Mitchell DM, Handa A, Kattapuram SV, Huang AJ. Imaging Findings of Metabolic Bone Disease. Radiographics. 2016;36(6):1871-1887. PMID: 27726750.