Correct Answer: B. Spinous process fracture
Spinous process fractures are the most common isolated fractures of the posterior elements of the spine, typically resulting from direct trauma or hyperextension injuries in road traffic accidents. The clinical presentation—back pain without neurological deficit—is pathognomonic for this injury. The spinous process is a bony prominence at the posterior midline of each vertebra, vulnerable to direct blunt force. On X-ray (lateral view), a spinous process fracture appears as a displaced or comminuted fragment at the posterior aspect of the vertebral body. Importantly, these fractures are stable injuries because they do not involve the vertebral body, intervertebral disc, or neural canal—hence the absence of neurological symptoms. The mechanism in RTA typically involves direct posterior impact or forceful hyperextension. Management is conservative with analgesia and activity modification; surgical intervention is rarely needed unless there is associated instability or neurological compromise. The key discriminator is the combination of isolated back pain, normal neurology, and a posterior element fracture visible on imaging.
Why the other options are wrong
A. Fracture of base of vertebrae — This is wrong because fractures of the vertebral body base (or compression fractures) involve the anterior column and typically present with pain AND neurological deficits if severe, or with kyphotic deformity on imaging. The question explicitly states no neurological deficit and the X-ray finding is consistent with a posterior element injury, not an anterior vertebral body fracture. NBE may use this to trap students who confuse 'back pain' with 'vertebral body injury.' C. Chance fracture — Chance fractures are horizontal splitting fractures through the vertebral body, pars interarticularis, and spinous process—a three-column injury caused by flexion-distraction (classically from lap-belt-only restraint in MVA). They are unstable and often present with neurological deficits and severe pain. The absence of neurological signs and the isolated posterior element finding rule this out. NBE pairs this with RTA to confuse students unfamiliar with the specific mechanism. D. Compressed fracture — Compression (crush) fractures involve the vertebral body and anterior column, causing loss of height and potential kyphosis. They present with anterior chest/back pain and may have neurological involvement if retropulsion occurs. The clinical picture of isolated posterior pain without neurological deficit, plus imaging showing a posterior element fracture, excludes this diagnosis. This is a common distractor for any 'spine fracture + RTA' scenario.
High-Yield Facts
- Spinous process fractures are the most common isolated posterior element fractures and are stable (no neurological deficit expected).
- Mechanism: Direct posterior blunt trauma or hyperextension injury; common in RTA with posterior impact.
- X-ray finding: Displaced or comminuted fragment at posterior midline on lateral view; anterior vertebral body and disc are intact.
- Management: Conservative—analgesia, NSAIDs, activity modification; surgery only if unstable or neurologically compromised.
- Chance fracture (flexion-distraction) is unstable and involves three columns; compression fracture involves vertebral body—both differ from isolated spinous process injury.
- Absence of neurological deficit rules out injuries involving the spinal canal (vertebral body fractures, retropulsion, disc herniation).
Mnemonics
SPINE FRACTURE STABILITY (Indian coaching shorthand) Posterior elements alone (spinous, lamina, facet) = STABLE. Anterior column (body, disc) = UNSTABLE. Three-column (Chance, burst) = UNSTABLE. Use: When you see 'back pain + no neuro deficit,' think posterior element = stable. RTA SPINE INJURY PATTERN Direct posterior hit → spinous fracture (stable). Lap-belt only → Chance (unstable). Axial load → burst (unstable). Flexion-rotation → dislocation (unstable). Use: Match mechanism to fracture type.
NBE Trap
NBE pairs "road traffic accident" with "back pain" to lure students into assuming vertebral body or unstable injury. The trap is forgetting that isolated posterior element fractures are stable and do NOT cause neurological deficit—the explicit absence of neuro signs is the key discriminator.
Clinical Pearl
In Indian emergency departments, spinous process fractures are often missed because they are "benign" and do not require urgent surgical intervention—but they are the most common isolated posterior element fracture seen in RTA. A patient with isolated back pain, normal neurology, and a posterior midline bony fragment on X-ray can be safely managed as an outpatient with NSAIDs and physiotherapy, avoiding unnecessary ICU admission.
_Reference: Bailey & Love Ch. 37 (Spine Injuries); Rockwood & Green's Fractures in Adults (Spine Trauma)_