The 3 Main Spinal Injuries After a Car Accident: Fracture, Disc Herniation, and Ligament Instability

By Dr. Justin M. Dick, DC, CNMT, ARRT(N)(CT) | Clear Life Scoliosis and Chiropractic Center, Charlotte, NC | Published October 16, 2026

After a car accident, imaging can document three kinds of structural spinal injury: a fracture, a disc herniation, and a ligament injury that lets one vertebra move farther on the next than it should. Each one is found with a different test. A normal result on one test says nothing about the other two. That is how I work up spinal injuries in Charlotte, and it is the framework Dr. Jeffrey Cronk, DC, JD, of Smart Injury Doctors and I use in our patient education material on the three main injuries.

The categories come from the American Medical Association's Guides to the Evaluation of Permanent Impairment. The Fourth Edition's injury model relies on neurologic deficits and on structural changes such as fractures, dislocations, and loss of motion segment integrity. A disc herniation enters that model when it compromises a nerve root, which is called radiculopathy. Other findings show up on post-crash MRI, bone marrow edema and soft tissue swelling among them. These three are the structural injuries the Guides rate, and that is why they anchor the workup.

Injury 1: Fracture

Emergency physicians decide who needs neck imaging with validated decision rules. Under the NEXUS criteria, a patient is cleared without imaging only when all five are met: no midline neck tenderness, no focal neurologic deficit, normal alertness, no intoxication, and no painful distracting injury. In 34,069 blunt trauma patients the rule missed 8 of 818 cervical injuries, a sensitivity of 99.0% (Hoffman, N Engl J Med 2000). The Canadian C-Spine Rule adds age 65 or older, a dangerous mechanism, and a test of active neck rotation. In a direct comparison across 8,283 patients, it was more sensitive than NEXUS, 99.4% versus 90.7% (Stiell, N Engl J Med 2003).

When imaging is needed, the choice of test matters. A meta-analysis of seven studies found a pooled sensitivity of 52% for cervical plain radiographs and 98% for computed tomography, or CT (Holmes and Akkinepalli, J Trauma 2005). The authors recommended CT first in high-risk patients and found the evidence insufficient to replace plain films in lower-risk patients who still need imaging. A patient who comes to my office with midline tenderness or new numbness after a crash goes for CT before anything else happens.

Injury 2: Disc Herniation

Magnetic resonance imaging, or MRI, is the test for disc herniation. Under the 2014 consensus nomenclature from the North American Spine Society and two radiology societies, a herniation is a focal displacement of disc material involving less than 25% of the disc circumference, subdivided into protrusion and extrusion by the shape of the displaced material (Fardon, Spine J 2014).

Disc findings have a known weakness in injury cases: they are common in people with no pain. A systematic review of 3,110 asymptomatic people found disc protrusion in 29% of 20-year-olds and 43% of 80-year-olds (Brinjikji, AJNR 2015). A protrusion on a post-crash MRI does not, by itself, show that the crash caused it. The timing of symptoms, neurologic findings that match the level, and any prior imaging of that level decide the question.

Injury 3: Ligament Instability

The third injury is damage to the ligaments that hold one vertebra to the next, measured as excessive motion between segments. The AMA Guides call it alteration of motion segment integrity and accept it only on plain-film lateral flexion and extension radiographs. MRI and CT are not used to rate it. The Fifth Edition flags cervical translation greater than 3.5 mm and cervical angular motion more than 11 degrees greater than an adjacent level. The Sixth Edition, published in 2008, uses percentage-based translation in the cervical spine and lumbar angular thresholds of more than 15 degrees at L1 through L4, 20 degrees at L4-L5, and 25 degrees at L5-S1, each compared with adjacent-level motion.

MRI is not blind to ligaments. In acute cervical trauma serious enough to need surgery, MRI detected 93% of posterior longitudinal ligament injuries and 100% of interspinous soft tissue injuries confirmed at surgery, but 71% of anterior longitudinal ligament injuries and 67% of ligamentum flavum injuries (Goradia, AJNR 2007). The limitation for a patient who walked away from the crash is different. MRI is taken lying still, and laxity shows up when the segment is loaded through motion. At a Charlotte spine center, supine MRI missed 28% of the spondylolisthesis levels seen on standing radiographs (Segebarth, J Spinal Disord Tech 2015). Those were degenerative cases, not trauma, but the positional problem is the same.

Why the Order of Testing Matters

Fracture is ruled out first because it changes everything after it, including whether motion films are safe to take. Disc herniation and ligament instability are then evaluated as separate questions with separate tests. The gap I see most often in records sent from other offices is a single MRI, read as a disc study, treated as a complete workup. That record answers one of the three questions.

The workup has limits that patients and attorneys should hear plainly. Documenting a fracture, a herniation, or instability establishes a structural injury. None of these tests measures pain, and none predicts how a particular patient will recover.

For an example of how post-collision imaging findings and outcomes are documented in the peer-reviewed literature, read Dr. Justin Dick's published case report on refractory lumbar pain following a motor vehicle accident in a geriatric patient.

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Frequently Asked Questions

What are the 3 main spinal injuries after a car accident?

The three structural spinal injuries imaging can document after a car accident are fracture, disc herniation, and spinal ligament instability. They correspond to the structural categories in the AMA Guides to the Evaluation of Permanent Impairment. Dr. Justin Dick evaluates all three in personal injury patients at Clear Life Scoliosis and Chiropractic Center in Charlotte, NC.

Can a normal MRI miss a spinal injury after a car accident?

Yes, for ligament instability. MRI is taken lying still, and excessive motion between vertebrae appears only when the spine moves. The AMA Guides accept motion segment integrity findings only on flexion and extension X-rays. In one Charlotte cohort, supine MRI missed 28% of spondylolisthesis levels seen on standing X-rays (Segebarth, J Spinal Disord Tech 2015).

Does an X-ray show a spinal fracture?

Not reliably in high-risk patients. A meta-analysis found pooled sensitivity of 52% for cervical plain X-rays and 98% for CT (Holmes and Akkinepalli, J Trauma 2005). CT is recommended first for high-risk trauma patients.

How is spinal ligament instability measured?

Spinal ligament instability is measured on lateral X-rays taken in flexion and extension. Under the AMA Guides Fifth Edition, cervical translation greater than 3.5 mm or angular motion more than 11 degrees greater than an adjacent level meets the threshold for alteration of motion segment integrity.

Does a disc herniation on MRI prove the accident caused it?

No, not by itself. Disc protrusion appears in 29% of pain-free 20-year-olds and 43% of pain-free 80-year-olds (Brinjikji, AJNR 2015). Symptom timing, neurologic findings at the matching level, and prior imaging are what connect a herniation to a specific collision.

Where can I get a spinal injury evaluation after a car accident in Charlotte, NC?

Dr. Justin Dick, DC, evaluates car accident spinal injuries at Clear Life Scoliosis and Chiropractic Center, 8814 Rachel Freeman Way, Suite 103, Charlotte, NC 28278, phone 980-368-0766. He holds dual imaging credentials, CNMT and ARRT(N)(CT). Personal injury patients are treated on a lien basis, with no out-of-pocket payment at the time of care.

Sources and Evidence Tiers

1. American Medical Association. Guides to the Evaluation of Permanent Impairment, Fourth, Fifth, and Sixth Editions.Evidence tier: Expert consensus (impairment rating guideline)
2. Hoffman JR, Mower WR, Wolfson AB, Todd KH, Zucker MI. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. N Engl J Med. 2000;343(2):94-99. PMID 10891516. LinkEvidence tier: Prospective multicenter cohort
3. Stiell IG, Clement CM, McKnight RD, et al. The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. N Engl J Med. 2003;349(26):2510-2518. PMID 14695411. LinkEvidence tier: Prospective comparative cohort
4. Holmes JF, Akkinepalli R. Computed tomography versus plain radiography to screen for cervical spine injury: a meta-analysis. J Trauma. 2005;58(5):902-905. PMID 15920400. LinkEvidence tier: Meta-analysis of observational studies (no RCTs)
5. Fardon DF, Williams AL, Dohring EJ, Murtagh FR, Gabriel Rothman SL, Sze GK. Lumbar disc nomenclature: version 2.0. Spine J. 2014;14(11):2525-2545. PMID 24768732. LinkEvidence tier: Expert consensus (NASS, ASSR, ASNR task forces)
6. Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015;36(4):811-816. PMID 25430861. LinkEvidence tier: Systematic review
7. Goradia D, Linnau KF, Cohen WA, Mirza S, Hallam DK, Blackmore CC. Correlation of MR imaging findings with intraoperative findings after cervical spine trauma. AJNR Am J Neuroradiol. 2007;28(2):209-215. PMID 17296981. LinkEvidence tier: Diagnostic accuracy cohort (31 surgical patients)
8. Segebarth B, Kurd MF, Haug PH, Davis R. Routine upright imaging for evaluating degenerative lumbar stenosis: incidence of degenerative spondylolisthesis missed on supine MRI. J Spinal Disord Tech. 2015;28(10):394-397. PMID 25353204. LinkEvidence tier: Retrospective cohort

Service Area

Clear Life Scoliosis and Chiropractic Center sees personal injury and spinal imaging patients from Charlotte NC, Huntersville NC, Ballantyne NC, Matthews NC, Concord NC, Mooresville NC, Rock Hill SC, and Fort Mill SC.

Related Pages

• Personal injury and car accident spinal care in Charlotte
• Dr. Justin Dick's research
• Case report: refractory lumbar pain after a motor vehicle accident
• Research and evidence at Clear Life
• Questions and answers
• Our team
• Press
• Book your evaluation
• Contact Clear Life

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This article is educational and is not a diagnosis. Imaging decisions depend on an in-person examination.