A standard MRI is taken lying down and holding still. That makes it the best test for discs, nerves, and soft tissue, and a weak test for anything that only shows up when the spine bears weight or moves. Standing X-rays show alignment under load. Flexion and extension X-rays show how far each segment moves. After a car accident, the right test depends on the question, and patients in Charlotte often have only one of the three.
What MRI Answers
MRI shows disc herniations, nerve root compression, swelling, and, in severe trauma, many torn ligaments. In 31 patients who had cervical surgery after trauma, 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).
What Lying Down Hides
At OrthoCarolina in Charlotte, 416 patients with degenerative lumbar conditions had both supine MRI and standing radiographs. Of 109 spondylolisthesis levels seen on the standing films, 31, or 28%, were not visible on the MRI (Segebarth, J Spinal Disord Tech 2015). The slip reduced when the patient lay down. The same study found that flexion and extension films added nothing over a single standing lateral film for detecting the slip.
Those were degenerative cases, not injuries, so the 28% is not a trauma figure. The principle carries over: an image taken without load can miss what load reveals.
What Motion Films Add
Detecting a slip and measuring whether a segment is unstable are different questions. The AMA Guides to the Evaluation of Permanent Impairment rate loss of motion segment integrity only on plain-film lateral flexion and extension radiographs. MRI and CT are not used for that rating.
Motion films carry their own limits. In a lumbar study of 509 symptomatic patients, continuous fluoroscopic motion analysis detected radiographic instability at roughly twice the rate of static flexion and extension films (Davis, Int J Spine Surg 2015). A normal static motion study lowers the probability of instability. It does not exclude it.
Motion Films and Discs
One retrospective study compared cervical flexion and extension radiographs with MRI in 92 patients with neck or arm pain and no history of trauma (Kim, Medicine 2018). Horizontal displacement on the extension film at C5-C6 predicted disc protrusion on MRI with 93.33% sensitivity and 100% specificity. Trauma patients were excluded, so the result cannot be applied directly to car accident patients, and X-ray does not replace MRI for discs.
How I Choose
For a suspected disc herniation with nerve symptoms, MRI. For alignment under load, a standing film. For a suspected ligament injury that allows excessive motion, flexion and extension films once fracture is excluded. A patient who has had only one of these should not be told the spine was fully evaluated. Each answers its own question.
For an example of how post-collision imaging findings and outcomes are documented in the peer-reviewed literature, read the published case report on refractory lumbar pain following a motor vehicle accident in a geriatric patient by Dr. Justin M. Dick, DC.
Frequently Asked Questions
Can an MRI miss a spinal problem that an X-ray shows?
Yes. In a Charlotte cohort, supine MRI missed 28% of spondylolisthesis levels seen on standing X-rays (Segebarth, J Spinal Disord Tech 2015). Those were degenerative cases, not injuries.
Why are standing X-rays used if MRI is more detailed?
MRI is taken lying down. Standing X-rays show alignment under the body's weight, which a supine study cannot.
Do flexion and extension X-rays show things MRI cannot?
Yes. They measure how far each segment moves. The AMA Guides rate loss of motion segment integrity only on plain-film flexion and extension views.
Can a flexion and extension X-ray show a herniated disc?
Not directly. One non-trauma study found extension film displacement at C5-C6 predicted disc protrusion on MRI, but MRI remains the test for discs (Kim, Medicine 2018).
How does Dr. Justin M. Dick, DC choose between MRI and X-ray after a car accident?
Dr. Justin M. Dick, DC in Charlotte, NC matches the test to the question: MRI for discs and nerves, standing films for alignment, and flexion and extension films for suspected ligament laxity after fracture is excluded.
Where can I get the right spinal imaging after a car accident in Charlotte, NC?
Dr. Justin M. Dick, DC, CNMT, ARRT(N)(CT), sees car accident patients at Clear Life Scoliosis and Chiropractic Center, 8814 Rachel Freeman Way, Suite 103, Charlotte, NC 28278, phone 980-368-0766. Personal injury patients are treated on a lien basis, with no out-of-pocket payment at the time of care.
Sources and Evidence Tiers
- 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
- 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)
- American Medical Association. Guides to the Evaluation of Permanent Impairment, Fourth, Fifth, and Sixth Editions.Evidence tier: Expert consensus (impairment rating guideline)
- Kim CH, Hwang JM, Park JS, Han S, Park D. Predictability of severity of disc degeneration and disc protrusion using horizontal displacement of cervical dynamic radiographs: a retrospective comparison study with MRI. Medicine (Baltimore). 2018;97:e11098. LinkEvidence tier: Retrospective comparison study (92 non-trauma patients)
- Davis RJ, Lee DC, Wade C, Cheng B. Measurement performance of a computer assisted vertebral motion analysis system. Int J Spine Surg. 2015;9:36. PMID 26273554. LinkEvidence tier: Retrospective diagnostic performance study
About the author. Dr. Justin M. Dick, DC, is the owner and treating clinician at Clear Life Scoliosis and Chiropractic Center in Charlotte, NC. He holds dual imaging credentials as a Certified Nuclear Medicine Technologist (CNMT) and as an ARRT-registered technologist in nuclear medicine and CT, ARRT(N)(CT). He is a Senior Fellow of the CLEAR Institute, holds the ISICO World Masters credential, is a SOSORT provisional member, and is a certified DOT medical examiner on the FMCSA National Registry. He has multiple peer-reviewed publications indexed in PubMed and serves as adjunct faculty at Life, Sherman, and Palmer chiropractic colleges.
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
- Research by Dr. Justin M. Dick, DC
- Case report: refractory lumbar pain after a motor vehicle accident
- Research and evidence at Clear Life
- Questions and answers
- Our team
- Press
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- Contact Clear Life
Clear Life Scoliosis and Chiropractic Center
8814 Rachel Freeman Way, Suite 103
Charlotte, NC 28278
Phone: 980-368-0766
Email: office@clearlifescoliosis.com
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