Spinous Process Fractures¶

Definition¶

Spinous process fractures are isolated fractures of the posterior bony projections of the vertebrae. Like transverse process fractures, they are classified as minor, non-structural injuries (AO Type A0) that do not affect spinal stability. However, they can occur in combination with more significant injuries and should prompt careful evaluation of the entire spine.

Mechanism of Injury¶

Spinous process fractures result from several mechanisms:

Direct trauma — A blow to the posterior midline of the spine
Avulsion — Forceful flexion against contracted extensor muscles, pulling the spinous process via the supraspinous and interspinous ligaments. This is the mechanism of the classic clay shoveler fracture (typically C6, C7, or T1).
Hyperflexion — The spinous process may fracture as part of a larger flexion-distraction injury when posterior tension band forces exceed the strength of the bone
Stress fracture — Repetitive loading, particularly in athletes

The lower cervical and upper thoracic spinous processes (C6–T3) are most commonly affected due to the large forces exerted by the trapezius, rhomboid, and nuchal ligament attachments. In the lumbar spine, spinous process fractures are less common as isolated injuries.

Imaging Findings¶

Radiography¶

Lateral view — A fracture line through the spinous process, which may appear as a "double spinous process" sign when the fragment is displaced inferiorly
Can be difficult to visualize, especially in the cervicothoracic region where overlapping structures obscure detail

CT¶

Fracture lines through the spinous process on sagittal and axial images
Degree of displacement
CT is important to evaluate for associated injuries — lamina fractures, facet fractures, or vertebral body fractures that would indicate a more significant injury pattern

Clinical Pearl

An isolated spinous process fracture is stable. However, spinous process fractures can also be a component of flexion-distraction injuries (AO Type B), where the fracture extends through the spinous process, lamina, pedicles, and into the vertebral body. If you see a spinous process fracture on CT, look carefully for widening of the interspinous space, facet joint widening, or vertebral body injury that would indicate a more serious injury pattern.

Relationship to Clay Shoveler Fracture¶

The clay shoveler fracture is a specific subtype of spinous process fracture — an avulsion fracture of the lower cervical or upper thoracic spinous process (C6, C7, or T1) caused by muscular avulsion forces. See the Clay Shoveler Fracture article for a detailed discussion.

Management¶

Isolated spinous process fractures are stable and treated conservatively with analgesics and activity modification. No bracing or surgical intervention is required. Recovery typically occurs within 4–6 weeks.

Key Points¶

Spinous process fractures are stable, posterior column-only injuries (AO Type A0)
Most common at C6–T3 from avulsion or direct trauma
The "double spinous process" sign on lateral radiograph suggests a displaced fragment
Always evaluate for associated injuries — a spinous process fracture may be the visible tip of a larger flexion-distraction injury
Treatment is conservative with excellent prognosis

References¶

Gaillard F, et al. Clay-shoveler fracture. Radiopaedia.org. https://radiopaedia.org/articles/clay-shoveler-fracture-2
Altunrende ME, Ekin EE. Traumatic isolated spinous process fractures. Ulus Travma Acil Cerrahi Derg (Turkish Journal of Trauma & Emergency Surgery). 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12000981/
Vu C, Gendelberg D. Classifications in Brief: AO Thoracolumbar Classification System. Clin Orthop Relat Res. 2020;478(2):434-440. https://pmc.ncbi.nlm.nih.gov/articles/PMC7438146/
Han SR, Sohn MJ. Twelve Contiguous Spinous Process Fracture of Cervico-Thoracic Spine. Korean Journal of Spine. 2014. https://pmc.ncbi.nlm.nih.gov/articles/PMC4206959/
Clay-Shoveler Fracture (Cervical Spinous Process Fractures). Orthobullets. https://www.orthobullets.com/spine/12284/clay-shoveler-fracture-cervical-spinous-process-fractures
AO Spine Classification of Thoracolumbar Fractures. The Radiology Assistant. https://radiologyassistant.nl/musculoskeletal/spine/ao-classification