Test library › Low back & pelvis
Femoral nerve stretch test (prone knee bend)
For: Upper lumbar (L2–L4) nerve root compression
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.
Rule-in strength not calculable (no false positives seen)Caution: For upper lumbar (L2–L4) nerve roots only; it does not detect L5/S1 compression, where sensitivity was 0% in the same study.
What the numbers mean
- Positive result: no false positives were seen in the study, so no likelihood ratio can be calculated. How far to trust that depends on how many people without the condition were studied.
- Negative result: a small shift: a negative result nudges the diagnosis down, but does not exclude it.
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. PubMed · single study
Figures as they will appear in Rule It In, Rule It Out (Trokos, forthcoming). If a newer or better study changes them, this page changes with the book. Figures last updated from the book on 2 October 2026.
Get the book for telling radicular leg pain from referred pain, and knowing when cauda equina means send now
This page gives the published figures. Rule It In, Rule It Out adds how to do this test, what counts as positive, how to read the result, and, where studied, whether combining it with other tests helps.
Coming in late 2026 as a PDF and a paperback. Join the list to hear when it's out
One study, one test, once a month
Rule It In is a free evidence letter for musculoskeletal clinicians: one recent study explained, one examination test with its real numbers. From Trokos, publisher of Rule It In, Rule It Out.