No, subluxations and slipped discs are distinct conditions
Subluxations refer to partial dislocations or misalignments of vertebral bodies, while "slipped disc" (herniated disc) describes displacement of the intervertebral disc material through its outer covering. These are separate pathological entities that can occur independently or together in spinal trauma.
Key Distinctions
Subluxation
- Definition: Partial dislocation or abnormal positioning of vertebral bodies relative to each other, typically measured as >3.5 mm displacement 1
- Mechanism: Results from ligamentous injury, facet joint disruption, or vertebral fractures
- Imaging: Best seen on plain radiographs, CT showing bony malalignment 1
Herniated Disc ("Slipped Disc")
- Definition: Herniation of the nucleus pulposus through the fibrous outer covering (annulus fibrosus), potentially compressing nerve roots 2
- Mechanism: Usually degenerative, though can be traumatic
- Imaging: Best visualized on MRI showing disc material deforming the thecal sac or nerve roots 3
Clinical Overlap in Trauma
While distinct entities, they frequently coexist in cervical spine trauma:
- 35-47% of cervical fracture-subluxations have associated disc herniations 4, 5
- Flexion-dislocation and flexion-compression injuries show the highest rates of concurrent disc herniation 4
- The presence of disc herniation in subluxation injuries does not contraindicate early closed reduction, with neurological deterioration occurring in only 0.5-2.4% of cases 6, 5
Important Clinical Pitfall
Do not assume subluxation automatically means disc herniation is present. In lumbar spine, retrolisthesis (posterior subluxation) can occur with or without disc herniation and represents a separate degenerative process 7. Each condition requires specific imaging assessment—subluxation is primarily a bony/ligamentous alignment problem, while disc herniation is a soft tissue pathology requiring MRI for definitive diagnosis 3.