Lower Limb Tension Tests : SLR Variations
Lower limb tension tests (LLTT), also known as neural tension tests, are used to evaluates the length and mobility of the components of the nervous system. This blog will discuss the 8 techniques of the lower extremity: sciatic, tibial, sural, common peroneal, femoral, lateral femoral cutaneous, obturator, and saphaneous nerves.
Testing of the sciatic nerve can be done via combinations of four different positions to incriminate the sciatic, tibial, sural, and common peroneal nerves. All sciatic nerve tests begin in the supine position and a straight leg raise (SLR) is performed, i.e. hip flexion, knee extension. Each of the tests would be deemed positive if the neurological symptoms are reproduced. The chart below distinguishes the defining characteristics for the testing of each the nerves:
Overall, SLR testing is highly variable. Statistically ranges as seem below are not clinically helpful.
- Sensitivity = 40-98%
- Specificity = 10-100%
- (+) Predictive value = 83%
- (-) Predictive value = 64%
- (+) Likelihood ratio = 1.0-1.98
- (-) Likelihood ratio = 0.05-0.86
- Reliability (Kappa) = 0.32-0.86
| Tibial | Sural | Common Peroneal |
Prone knee bend testing allows for the assessment of the femoral, lateral femoral cutaneous, obturator, and saphenous nerves. All of these tests begin in the prone position. The chart below differentiates the various positions for each nerve:
A positive test is a reproduction of the neurological symptoms. Unfortunately, there is not any literature on sensitivity but specificity is very high (84%) while the reliability of testing is low (Kappa = 0.21-0.26).
| Femoral | Lateral Femoral Cutaneous | Obturator | Saphaneous |
Once determined there is a concern with the mobility of a nerve, the same positioning maneuvers can be used as treatment. This is called neural flossing. It is a gentle technique in which tension is briefly applied to the nerve in the specific position described. The tension is removed and reapplied for several repetitions, i.e. “pressure on, pressure off” for 10-15 repetitions. Paresthesia may be experienced during the “pressure on” phase but should diminish during the “pressure off” phase. The purpose of neural flossing is to free a nerve of adhesions and increase mobility.
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