Femoral Nerve Tension Test
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The Femoral Nerve Tension Test also known as the Femoral Nerve Stretch (Test) is a test used to screen for sensitivity to stretch soft tissue at the dorsal aspect of the leg, possibly related to nerve root impingements.
The test is performed with the patient lying in prone. The examiner facilitates gentle knee flexion to its maximum. If no positive result appears (a positive result in this test means that it induces pain in the groin, anterior or posterior thigh, buttocks or lumbar region or while the knee is brought in flexion between 80 and 100 degrees), (s)he brings the hip to further extension.
The femoral nerve tension test is used to screen for sensitivity to stretch soft tissue at the dorsal aspect of the leg, possibly related to root impingements.
Clinically Relevant Anatomy
The Femoral Nerve comes from the Plexus Lumbosacralis (more specific the Plexus Lumbalis) and branches out into the N. Saphenus, the Rr. Musculares and the Rr. Cutanei Femoris Anteriores. This ramification happens usually about 2.5 cm under the inguinal ligament.
The femoral nerve lies within Scarpa’s triangle (or the ‘Trigonum Femorale Mediale’) which is bounded by the inguinal ligament (superiorly), the medial border of the Sartorius muscle and the lateral border of the Adductor Longus muscle (The muscles Pectineus and Iliopsoas lie within this triangle as well).
The femoral nerve lies (most laterally) next to the femoral artery and femoral vein (medially). 
The patient lies prone and the therapist stabilizes the pelvis to prevent anterior rotation. The therapist then maximally flexes the knee to end range. If no positive signs are noted in this position, the therapist proceeds to extending the hip while maintaining knee flexion.
If unilateral pain is produced in the lumbar region, buttocks, posterior thigh or between the ranges of 80-100 degrees of knee flexion in a combination of these regions, the test is considered positive. The dura is tensioned between 80 and 100 degrees and positive findings in this range could be indicative of a disk herniation affecting the L2, L3 OR L4 nerve root. Positive findings secondary to a disk herniation can be differentiated from quad problems based upon the range in which pain is reproduced. If pain is produced before 80 degrees of knee flexion, quad tightness and/or injury may be the cause.
In some cases, when a patient is suspected to have a lateral L4/5 disc protrusion, the femoral nerve tension test might induce ipsilateral sciatica. The L4 nerve root is moved downward and stretched when the femoral nerve tension test is performed. In Christodoulides’ research all patients (n=40) subjected to this test were verified using myleography (an examination that involves the injection of contrast material in the space around the spinal cord and nerve roots using a real-time form of x-ray called fluoroscopy) The criteria for selecting patients were only that they were suspected to have a lateral L4/5 disc protrusion. 
The femoral nerve tension test can also be used to screen for high lumbar radiculopathy (a description for several symptoms, where the origination of the problem is near the root nerves in the spine, causing the nerves not to work properly ), but in some cases this may prove unreliable. For example when an individual who has tight or injured muscles on the anterior side of his/her thigh undergoes this test, it might prove to be falsely positive, especially because the diagnosis is considered positive when it induces pain in the groin, anterior or posterior thigh, buttocks or lumbar region. 
In research performed by Pradeep Suri and others, they experienced that the femoral nerve stretch test is one of the most reliable tests to screen for midlumbar (L2, L3 or L4 levels) nerve root impingement (results between 88 and 100%). The chances of this test being positive grow as the population ages and although pain is usually provoked only in the groin and anterior thigh, it may also be experienced in the calf, ankle or foot. In contrary to other research, the crossed femoral nerve stretch (performed similarly but with contralateral knee flexion) test didn’t provide additional gain in specificity. Individual physical examination tests such as the Femoral nerve stretch test may provide clinical information that substantially alters the likelihood that midlumbar impingement, low lumbar impingement, or level-specific impingement is present. Test combinations improve diagnostic accuracy for midlumbar impingement. 
Clinical Bottom Line
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Recent Related Research (from Pubmed)
- [Investigation of the quadriceps strength in patients with chronic obstructive pulmonary disease].
- Quadriceps strength assessed by magnetic stimulation of the femoral nerve in normal subjects.
- Non-invasive mechanical ventilation improves walking distance but not quadriceps strength in chronic respiratory failure.
- Quadriceps muscle weakness following acute hemiplegic stroke.
- Submaximal motor unit firing rates after 8 wk of isometric resistance training.
- Crossed femoral stretching test. A case report.
- Rerouting peripheral nerves for spinal cord lesions.
- ↑ Picture found on http://karate.butsu.net/anatomy/lumbosacral.html
- ↑ Schünke M, Schulte E, Schumacher U, Voll M, Wesker K. Prometheus anatomy. Houten: Bohn Stafleu van Loghum, 2005.
- ↑ Dutton, M. (2008). Orthopaedic: Examination, evaluation, and intervention (2nd ed.). New York: The McGraw-Hill Companies, Inc.
- ↑ Online video, www.youtube.com/watch?v=9Hucq7bZO24, last accessed 06/04/09.
- ↑ Antonios N. Christodoulides. Ipsilateral Sciatica on femoral nerve stretch test is pathognomonic of an L4/5 protrusion. The Journal of Bone and joint Surgery 1989; 71-B: 88-89. http://www.ncbi.nlm.nih.gov/pubmed/2915013 Level of evidence: C
- ↑ http://www.radiculopathy.net/
- ↑ Scott F. Nadler, DO, Gerard A. Malanga, MD, Todd P. Stitik, MD, Rohit Keswani, MD, Patrick M. Foye, MD. The Crossed Femoral Nerve Stretch Test to Improve Diagnostic Sensitivity for the High Lumbar Radiculopathy: 2 Case Reports. Arch Phys Med Rehabil 2001; 82: 522-523. http://www.ncbi.nlm.nih.gov/pubmed/11295015 Level of evidence: B
- ↑ Pradeep Suri, MD, James Rainville, MD, Jeffrey N. Katz, MD, MS, Cristin Jouve, MD, Carol Hartigan, MD, Janet Limke, MD, Enrique Pena, MD, Ling Li, MPH, Bryan Swaim, MS, and David J. Hunter, MBBS, PhD. The Accuracy of the Physical Examination for the Diagnosis of Midlumbar and Low Lumbar Nerve Root Impingement. SPINE 2010, Lippincott Williams &amp;amp;amp;amp; Wilkins. (Published online ahead of print) http://www.ncbi.nlm.nih.gov/pubmed/20543768 Level of evidence: B