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Mid-lumbar (L2–L4) nerve root screen: 4-test combination

For: Upper lumbar (L2–L4) nerve root compression

Website-only test: not part of the book.

Compression of an upper lumbar nerve root (L2 to L4), which supplies the front of the thigh. Causes pain in the front of the thigh and sometimes weakness of the quadriceps.

Treat with caution (see below)
Sensitivity80%
Specificity90%
LR+ (positive)7.7
LR− (negative)0.22

Likelihood ratios as published by the study.

Caution: All patients had nerve root compression on MRI, so this tells the level (L2–L4 rather than L5/S1), not whether compression is present; small single study.

How it is done

Do four tests; the combination is positive if ANY one is abnormal: (1) femoral nerve stretch test — patient prone, the examiner bends the knee on the painful side; positive if it reproduces the usual leg pain; (2) single-leg sit-to-stand — from sitting, the patient holds the other foot off the floor and tries to stand up on the tested leg alone, with hands held for balance only; positive if unable; (3) reduced knee (patellar) reflex; (4) reduced pinprick sensation at the inner (medial) ankle.

What the studies found

Locates the level of nerve root compression: mid-lumbar (L2–L4) rather than L5/S1. Suri 2011 studied 54 patients with acute radicular leg pain (under 12 weeks) at a hospital spine centre, examined by physiatrists blinded to the MRI. Every patient had nerve root compression on MRI (25 mid-lumbar, 29 at L5/S1), so the specificity is against L5/S1 compression, not against having no compression: the combination tells the level, not whether compression is present. Sensitivity 80% (95% CI 61–91%), specificity 90% (74–96%), LR+ 7.7 (2.6–23), LR− 0.22 (0.10–0.49). Small single study; the combination was chosen after looking at the data, which can flatter accuracy. The femoral nerve stretch test alone, from the same study, is a separate entry.

What the numbers mean

  • Positive result: see the caution above before relying on this result.
  • Negative result: a small shift: a negative result nudges the diagnosis down, but does not exclude it.

The ladder: what a result does to your estimate

If you thoughtAfter a positiveAfter a negative
10%46%2%
30%77%9%
50%89%18%

Calculated from the likelihood ratios above. Read the caution above before relying on these. For any other starting estimate, use the probability calculator.

Work out what a result means for your patient: probability calculator

Other tests in the library for upper lumbar (L2–L4) nerve root compression

Source

Suri P, Rainville J, Katz JN, Jouve C, Hartigan C, Limke J, Pena E, Li L, Swaim B, Hunter DJ. The accuracy of the physical examination for the diagnosis of midlumbar and low lumbar nerve root impingement. Spine (Phila Pa 1976). 2011;36(1):63–73. Journal article (DOI) · single study

Website-only test: added to the library on 9 October 2026 and not part of Rule It In, Rule It Out. Figures independently checked against the sources cited above; any note above says where only the abstract could be checked. If a newer or better study changes them, this page will be updated.

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This test is in the website library only; it is not one of the tests in Rule It In, Rule It Out. The book covers the tests in its ‘The low back and pelvis’ chapter: how to do each one, what counts as positive, and how to read the result.

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