Musculoskeletal lower back pain

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Imaging is not required for musculoskeletal low back pain lasting <6 weeks, in the absence of red-flag features or suspicion of an underlying disease or alternate diagnosis.[3]American College of Radiology. ACR appropriateness criteria: low back pain. 2021 [internet publication]. https://acsearch.acr.org/docs/69483/Narrative [65]Chou R, Qaseem A, Owens DK, et al. Diagnostic imaging for low back pain: advice for high-value health care from the American College of Physicians. Ann Intern Med. 2011 Feb 1;154(3):181-9. http://annals.org/article.aspx?articleid=746774 http://www.ncbi.nlm.nih.gov/pubmed/21282698?tool=bestpractice.com

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MRI without intravenous contrast is the preferred first-line investigation for the majority of patients with symptom duration greater than 6 weeks.[3]American College of Radiology. ACR appropriateness criteria: low back pain. 2021 [internet publication]. https://acsearch.acr.org/docs/69483/Narrative

Can eliminate fracture, spondylolisthesis, and tumour/abscess diagnoses.

MRI should be ordered in the following circumstances: suspect radiculopathy or spinal stenosis in potential candidates for surgery; suspect cauda equina; post-surgical lower back pain; unexplained weight loss; immunosuppression; history of cancer; intravenous drug use; prolonged use of corticosteroids; or persistent pain >6 weeks' duration.[3]American College of Radiology. ACR appropriateness criteria: low back pain. 2021 [internet publication]. https://acsearch.acr.org/docs/69483/Narrative  

MRI is of limited diagnostic value in acute non-specific lower back pain. Studies have revealed disc protrusions, degenerative changes, and spinal stenosis in asymptomatic patients who should not undergo any intervention.[3]American College of Radiology. ACR appropriateness criteria: low back pain. 2021 [internet publication]. https://acsearch.acr.org/docs/69483/Narrative [66]Boden SD, Davis DO, Dina TS, et al. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am. 1990 Mar;72(3):403-8. http://www.ncbi.nlm.nih.gov/pubmed/2312537?tool=bestpractice.com [67]Jensen MC, Brant-Zawadzki MN, Obuchowski N, et al. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med. 1994 Jul 14;331(2):69-73. https://www.nejm.org/doi/10.1056/NEJM199407143310201 http://www.ncbi.nlm.nih.gov/pubmed/8208267?tool=bestpractice.com [68]Jarvik JJ, Hollingworth W, Heagerty P, et al. The Longitudinal Assessment of Imaging and Disability of the Back (LAIDBack) Study: baseline data. Spine (Phila Pa 1976). 2001 May 15;26(10):1158-66. http://www.ncbi.nlm.nih.gov/pubmed/11413431?tool=bestpractice.com

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X-rays may be sufficient for the initial evaluation of the following patient groups: recent significant trauma (at any age), minor fall or heavy lift in a potentially osteoporotic or elderly person.[3]American College of Radiology. ACR appropriateness criteria: low back pain. 2021 [internet publication]. https://acsearch.acr.org/docs/69483/Narrative  

Can eliminate fracture, spondylolisthesis, or tumour diagnoses.

X-rays should not be ordered for non-specific lower back pain of <6 weeks' duration as it has no effect on outcomes.[65]Chou R, Qaseem A, Owens DK, et al. Diagnostic imaging for low back pain: advice for high-value health care from the American College of Physicians. Ann Intern Med. 2011 Feb 1;154(3):181-9. http://annals.org/article.aspx?articleid=746774 http://www.ncbi.nlm.nih.gov/pubmed/21282698?tool=bestpractice.com [69]Kendrick D, Fielding K, Bentley E, et al. Radiography of the lumbar spine in primary care patients with low back pain: randomised controlled trial. BMJ. 2001 Feb 17;322(7283):400-5. http://www.bmj.com/content/322/7283/400.full http://www.ncbi.nlm.nih.gov/pubmed/11179160?tool=bestpractice.com [70]Chou R, Fu R, Carrino JA, et al. Imaging strategies for low-back pain: systematic review and meta-analysis. Lancet. 2009 Feb 7;373(9662):463-72. http://www.ncbi.nlm.nih.gov/pubmed/19200918?tool=bestpractice.com

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Not as useful as MRI for depicting disc protrusions.

Better than MRI for identifying bony pathology.

CT should be ordered in the following circumstances: if MRI contraindicated; need to depict details of spondylolysis, pseudoarthrosis, or scoliosis; persistent suspicion of vertebral body fracture despite normal lumbar spine x-ray; or detailed view of surgical fusion, instrumentation, or bone graft integrity is needed.[3]American College of Radiology. ACR appropriateness criteria: low back pain. 2021 [internet publication]. https://acsearch.acr.org/docs/69483/Narrative

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Sensitivity of spinal stenosis using myelography (67% to 78%) is lower than with CT and MRI.[71]Kent DL, Haynor DR, Larson EB, et al. Diagnosis of lumbar spinal stenosis in adults: a metaanalysis of the accuracy of CT, MR, and myelography. AJR Am J Roentgenol. 1992 May;158(5):1135-44. http://www.ajronline.org/doi/pdf/10.2214/ajr.158.5.1533084 http://www.ncbi.nlm.nih.gov/pubmed/1533084?tool=bestpractice.com

Disadvantages include requirement for contrast and lumbar puncture, thus seldom used.

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Normal WBC count suggests active infections such as osteomyelitis are less likely.

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Normal ESR suggests active infections (e.g., osteomyelitis), active rheumatological disease, or neoplasia are less likely.

If ESR is elevated, further work-up is warranted.

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Normal CRP suggests active infections (e.g., osteomyelitis), active rheumatological disease, or neoplasia are less likely.

If CRP is elevated, further work-up is warranted.

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Normal urinalysis (absence of WBCs/RBCs) and culture suggests acute pyelonephritis is unlikely.

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Negative blood culture suggests osteomyelitis is less likely.

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Negative technetium polyphosphate test can rule out the diagnosis of osteomyelitis. In general, the test is only necessary if radiographic results are ambiguous.

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Normal EMG evaluation rules out a peripheral neuropathy or plexopathy (e.g., diabetic peripheral neuropathy/diabetic amyotrophy).