Are You Getting False Negatives in the Athlete?
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Learn how to apply the straight leg raise to back pain and sciatica from severe pain to the athlete.
Course description. REGISTER NOW! Melbourne, Australia
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WATCH HOW TO DO THE STRAIGHT LEG RAISE - IN DETAIL
Next in-person course: Lower Quarter 1, Melbourne, July 30-31, 2022
Hosts: Ben Lustig Physiotherapy, Geelong Physical Therapy Instructor: Michael Shacklock, MAppSc, FACP |
ARTICLE - Our Recent Research: Reliability of the Extended Straight Leg Raise - Applicable to Athletes
Are you missing the neural aspect to the athlete's problem?
False negatives.
RELIABILITY OF THE EXTENDED STRAIGHT LEG RAISE
Introduction The straight leg raise (SLR) is the world's most performed neurodynamic test. It has existed for more than 4,000 years with the Egyptian physician Imhotep using it on patients with back pain injured during the pyramid era. These days, the manoeuvre is typically rated against MRI evidence of lumbar disc hernia and/or nerve root compression, producing the following sensitivity and specificity (Majlesi et al 2008) for nerve root compression: Sensitivity - 0.84. Specificity - 0.88. |
Key issue - reliability is key to all physical tests. Some studies do not test it, or they do it in asymptomatic subjects but not in a clinical sample with a recognized diagnosis.
So we wanted to test reliability of the straight leg raise in patients with nerve root compression on MRI. Another part was to see if movements that increase tension in the sciatic nerve above the usual SLR can be reliable. We think these extra movements might be a way of changing diagnostic efficacy and improving our understanding of its mechanisms. |
Definitions
SLR - only hip flexion with the extended knee.
Extended (E)SLR - added ankle dorsiflexion and internal hip rotation. These movements increase tension in the lumbosacral nerve roots and sciatic nerve.
Abnormal (positive) SLR - reproduction of clinical symptoms that change with dorsiflexion and/or internal rotation.
Differentiation - when movement of the neural structures in the problem area occurs by movement from another area whilst not moving the musculoskeletal structures in the area of the problem, e.g. dorsiflexion moves the lumbosacral nerve roots during the SLR but it does not move the spine.
SLR - only hip flexion with the extended knee.
Extended (E)SLR - added ankle dorsiflexion and internal hip rotation. These movements increase tension in the lumbosacral nerve roots and sciatic nerve.
Abnormal (positive) SLR - reproduction of clinical symptoms that change with dorsiflexion and/or internal rotation.
Differentiation - when movement of the neural structures in the problem area occurs by movement from another area whilst not moving the musculoskeletal structures in the area of the problem, e.g. dorsiflexion moves the lumbosacral nerve roots during the SLR but it does not move the spine.
We tested the reliability of responses of the extended SLR (dorsiflexion and internal hip rotation) in a low back pain population.
Methods
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Control group (n=20)
- pain in low back and/or pelvis - no pain below knee - normal ESLR: no reproduction of clinical symptoms, no change in response with dorsiflexion or hip rotation. |
Sciatica group (n=20)
- pain in low back and/or pelvis and sciatica - pain below knee - abnormal ESLR: reproduction of clinical pain, change in clinical pain with dorsiflexion and hip rotation. |
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Results
Inter-rater agreement between Examiner 1 and Examiner 2: 0.85 (p < 0.001, 95%CI: 0.71–0.99). Extremely good agreement in Cohen’s Kappa (Figure 1). |
Figure 1.
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Discussion and Conclusions - When To Extend the SLR and When Not To
Adding dorsiflexion and internal rotation to the usual straight leg raise was highly reliable in this population of lumbar nerve root compression from disc hernia.
That's all very well but how is this relevant to clinical practice and how can we apply this?
Even though found to be reliable, we must remember that hip rotation and dorsiflexion increase tension in the sciatic nerve. CHOICE of movement would therefore be determined by the PURPOSE of the movement and would be based on patient features.
Back pain could be differentiated with dorsiflexion, but internal rotation may not be necessary (or safe) in the patient with severe reproducible pain. If differentiation of clinical symptoms failed with the usual SLR (no hip rotation) and the problem were only mild, dorsiflexion would still be used for DIFFERENTIATION and internal rotation to INCREASE FORCE (a higher progression) and likelihood of detecting an abnormal response (more sensitive).
So internal rotation may be used as a reliable progression for patients in whom 'exclusion' is important at higher levels of function where their standard SLR is normal.
If then the extended SLR (internal rotation) reproduces clinical pain when the standard test did not, the test fails the exclusion test and would then change the response from normal to abnormal. The patient may then become a candidate for neurodynamic treatment when originally they were MISSED BY A FALSE NEGATIVE. You can avoid false negatives with appropriate progressions.
We think this progression may reduce the number of false negatives, particularly in higher functioning patients such as athletes in whom the standard SLR is not a high enough test.
Adding dorsiflexion and internal rotation to the usual straight leg raise was highly reliable in this population of lumbar nerve root compression from disc hernia.
That's all very well but how is this relevant to clinical practice and how can we apply this?
Even though found to be reliable, we must remember that hip rotation and dorsiflexion increase tension in the sciatic nerve. CHOICE of movement would therefore be determined by the PURPOSE of the movement and would be based on patient features.
Back pain could be differentiated with dorsiflexion, but internal rotation may not be necessary (or safe) in the patient with severe reproducible pain. If differentiation of clinical symptoms failed with the usual SLR (no hip rotation) and the problem were only mild, dorsiflexion would still be used for DIFFERENTIATION and internal rotation to INCREASE FORCE (a higher progression) and likelihood of detecting an abnormal response (more sensitive).
So internal rotation may be used as a reliable progression for patients in whom 'exclusion' is important at higher levels of function where their standard SLR is normal.
If then the extended SLR (internal rotation) reproduces clinical pain when the standard test did not, the test fails the exclusion test and would then change the response from normal to abnormal. The patient may then become a candidate for neurodynamic treatment when originally they were MISSED BY A FALSE NEGATIVE. You can avoid false negatives with appropriate progressions.
We think this progression may reduce the number of false negatives, particularly in higher functioning patients such as athletes in whom the standard SLR is not a high enough test.
References
Majlesi J, Togay H, Ünalan H, Toprak S 2008 The sensitivity and specificity of the slump and the straight leg raising tests in patients with lumbar disc herniation. Journal of Clinical Rheumatology (2): 87-91. DOI: 10.1097/RHU.0b013e31816b2f99
Majlesi J, Togay H, Ünalan H, Toprak S 2008 The sensitivity and specificity of the slump and the straight leg raising tests in patients with lumbar disc herniation. Journal of Clinical Rheumatology (2): 87-91. DOI: 10.1097/RHU.0b013e31816b2f99
Pesonen J, Shacklock M, Rantanen P, Mäki J, Karttunen L, Kankaanpää M, Airaksinen O, Rade M 2021 Extending the straight leg raise test for improved clinical evaluation of sciatica: reliability of hip internal rotation or ankle dorsiflexion. BMC Musculoskeletal Disorders (2021) 22:303. DOI: 10.1186/s12891-021-04159-y