Flashcards in Low back/back Deck (4)
Femoral Nerve Tension Test
The prone knee bending test is a neural tension test used to stress the femoral nerve and the mid lumbar (L2-L4) nerve roots.
The patient is prone symmetrically on the bed, the clinician places one hand on the patient's pelvis to prevent movement and feel for any compensations, while the other hand flexes the involved knee as much as possible and maintain the position for 45 seconds. A positive test will be reproduction of the patient's symptoms. Then raising the hip into extension can be used.
Pain following the femoral nerve or the mid lumbar roots (Lower back area, anterior thigh) can direct the clinician to entrapment of the nerve and L2-L4 roots. A tight rectus femoris can also produce pain in the anterior thigh, thus it is important to perform the test on both sides and compare the symptoms
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 disc 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.
Can be performed Sidelying
Straight Leg Raise Test
The straight leg raise is a passive test. Each leg is tested individually with the normal leg being tested first. When performing the SLR test, the patient is positioned in supine without a pillow under his/her head, the hip medially rotated and adducted, and the knee extended. The clinician lifts the patient's leg by the posterior ankle while keeping the knee in a fully extended position. The clinician continues to lift the patient's leg by flexing at the hip until the patient complains of pain or tightness in the back or back of the leg.[1
If symptoms are primarily back pain, it is most likely the result of a disc herniation applying pressure on the anterior theca of the spinal cord, or the pathology causing the pressure is more central. "Back pain only" patients who have a disc prolapse have smaller, more central prolapses.
If pain is primarily in the leg, it is more likely that the pathology causing the pressure on neurological tissue(s) is more lateral.
Disc herniations or pathology causing pressure between the two extremes are more likely to cause pain in both areas.
Neurologic pain which is reproduced in the leg and low back between 30-70 degrees of hip flexion is suggestive of lumbar disc herniation at the L4-S1 nerve roots.
Pain at less than 30 degrees of hip flexion might indicate acute spondyloithesis, gluteal abscess, disc protrusion or extrusion, tumor of the buttock, acute dural inflammation, a malingering patient, or the sign of the buttock.
Pain at greater than 70 degrees of hip flexion might indicate tightness of the hamstrings, gluteus maximus, or hip capsule, or pathology of the hip or sacroiliac joints.
Pain that increases with neck flexion or foot dorsiflexion or both indicates stretching of the dura mater of the spinal cord or a lesion within the spinal cord (e.g. disc herniation, tumor, or meningitis) 
Pain that does not increase with neck flexion may indicate a lesion in the hamstring area (tight hamstrings) or in the lumbosacral or sacro-iliac joint.
Femoral Tension Test efectiveness
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.