Traction Spur

A traction spur is a horizontally directed osteophyte on the anterior surface of the vertebral body that arises 2 mm - 3 mm from the endplate. Spinal levels with segmental instability tend to develop these spurs, likely due to abnormal stress placed on the outermost layers of the attachment of the annulus fibrosus, which attach on the vertebral body 2 mm - 3 mm from the endplate and are strongest and most numerous anteriorly.

Early on, radiographs reveal a small horizontally directed bony excrescence immediately above or below the discal edge of the vertebral body. The bony excrescence gets larger as time passes, but never curves at its tip. When the instability is treated with fusion, the traction spur regresses.

The image above shows a small traction spur at the anteroinferior margin of L5. We also see evidence of disc vaccum phenomenon, which is another sign of segmental instability.

The traction spur can be differentiated from the claw or marginal spur by its lack of a curve at the tip.

References

Macnab I. The traction spur. An indicator of segmental instability. J Bone Joint Surg Am. 1971 Jun;53(4):663-70.