Computerized X-ray mensuration is the use of software to measure angles and distances on a spinal X-ray after the clinician marks anatomical landmarks. I use PostureRay to measure flexion and extension films for patients in Charlotte. The software makes the arithmetic consistent. It does not make the diagnosis, and the published evidence on it is narrower than its marketing. Clear Life has no financial relationship with PostureCo, the developer.
What the Software Does
The clinician marks the corners of each vertebral body on the film. The software then calculates translation, how far one vertebra slides on the next, and angulation, how much the two tilt toward each other. On flexion and extension films, those values are compared with the AMA Guides thresholds for loss of motion segment integrity, such as cervical translation greater than 3.5 mm or angular motion more than 11 degrees greater than an adjacent level in the Fifth Edition.
What Has Been Tested
One study compared PostureRay with hand-drawn measurements and found they agreed. It used drawn rectangles in place of patient radiographs (Fedorchuk, Curr Med Imaging 2023). That tests the software's arithmetic, not its performance on real anatomy.
A second study tested a computer-vision measurement method on 254 lateral cervical radiographs and reported excellent reliability for sagittal alignment measures. Its coauthors include researchers affiliated with the developer (Hosseini, J Clin Med 2024). It tested resting alignment, not flexion and extension instability.
I have not found a peer-reviewed study that validates PostureRay's flexion and extension instability analysis against a reference standard such as surgical findings or patient outcomes.
Where Error Comes From
Every motion measurement carries error, whatever tool is used. In a lumbar study, coefficients of repeatability for rotation and translation ranged from 1.99 to 3.11 depending on method and reader (Davis, Int J Spine Surg 2015). The largest source of variation in software measurement is the human step: where the corners are marked. A value close to a threshold is not a clear result in either direction.
Normal Values for Context
A study of 75 normal subjects digitized dynamic cervical radiographs and found nearly all angular differences between levels in flexion were under 7 degrees, measured against C2-C3 (Lin, Spine 2001). The 11-degree threshold sits above that range.
How I Report It
A report from my office lists each level measured, the translation and angular values, which edition of the AMA Guides was applied, and the threshold. Values near a threshold are reported as near. The diagnosis comes from those measurements together with the exam and history. Anyone reviewing the report can check every number against the film.
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
What is computerized X-ray mensuration?
It is the use of software to measure angles and distances on a spinal X-ray after the clinician marks anatomical landmarks such as vertebral body corners.
What does PostureRay measure?
It calculates translation and angulation between vertebrae from marked landmarks. On flexion and extension films, those values can be compared with AMA Guides thresholds.
Is PostureRay validated?
One study found it matched hand measurements on drawn rectangles, and another found excellent reliability for resting cervical alignment. No peer-reviewed study validates its flexion and extension instability analysis against surgical findings or outcomes.
How accurate are spinal motion measurements?
They carry measurable error. In one lumbar study, coefficients of repeatability ranged from 1.99 to 3.11 (Davis, Int J Spine Surg 2015).
Does Dr. Justin M. Dick, DC have a financial relationship with PostureCo?
No. Dr. Justin M. Dick, DC in Charlotte, NC uses PostureRay for measurement and has no financial relationship with the developer.
Where can I get flexion and extension X-rays measured 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
- Fedorchuk C, Comer RD, McRae C, Bak D, Lightstone DF. Validity of radiographic analyses between hand-drawn and computer-aided measurements: a double-blinded test-retest trial. Curr Med Imaging. 2023;19(9):1071-1078. PMID 36748215. LinkEvidence tier: Measurement validity study on drawn renderings, not patient radiographs
- Hosseini MM, Mahoor MH, Haas JW, et al. Intra-examiner reliability and validity of sagittal cervical spine mensuration methods using deep convolutional neural networks. J Clin Med. 2024;13(9):2573. PMID 38731102. LinkEvidence tier: Reliability study; coauthors affiliated with the software developer
- 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
- American Medical Association. Guides to the Evaluation of Permanent Impairment, Fourth, Fifth, and Sixth Editions.Evidence tier: Expert consensus (impairment rating guideline)
- Lin RM, Tsai KH, Chu LP, Chang PQ. Characteristics of sagittal vertebral alignment in flexion determined by dynamic radiographs of the cervical spine. Spine. 2001;26(3):256-261. PMID 11224861. LinkEvidence tier: Cross-sectional normative study (75 subjects)
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
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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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