Those of us that work with patients that have low back complaints will often do the Passive Straight Leg (PSLR) test to see if it reproduces their low back symptoms and/or radicular symptoms. The general thought is that a positive test: between 0-35◦ (we may be thinking extradural involvement), between 35-70◦ (we may be thinking more disc involvement) and between 70-90◦ (we may be thinking more lumbar joint involvement) (1,2). Generally (very generally), if there are any radiating symptoms beyond the low back and into the leg but, above the knee, we often think of this as more of a low back/SI joint problem and lumbar sprain/strain with some possible muscular referral pain. However, if there are radiating symptoms past the knee into the lower leg and/or into the foot we may have a higher suspicion that there is a disc bulge/herniation, spinal stenosis or other space occupying lesion. This can then be further confirmed by a well leg raise test and Braggard’s test. However, as many of us dealing with musculoskeletal complaints and problems day to day know, these tests are often negative and/or inconclusive at best. And so, we’re left with some information but, not the entire story. I would submit that the following study produced some clues that could add an extra layer to your general functional orthopedic evaluation to help delineate if the patient: (1) Is in need of exercise and rehabilitation (2) Requires more diagnostic imaging or procedures or (3) Requires a combination of the two or by doing a PSLR (4) Requires some mobility and mobilization prior to rehabilitation.
This study looked at the utility of the “Active” Straight Leg Raise (ASLR) Test as a screen for lumbar spine stability and abdominal bracing ability. While the study sample was small at 14 participants, it clearly demonstrated that abdominal bracing (AB) reduced lumbar rotation as well as increase lumbar stiffness both of which are very important in reducing the overall stresses/forces on the spines of all our lumbar spine patients during their daily activities. AB has also been shown in prior investigations (3,4) to reduce lumbar spine axial rotation and with this study certainly suggests that it may be a suitable countermeasure for patients whose pain is induced by excessive motion of the lumbar spine or pelvis.
What does this mean to you during your exam? Here’s a very loosely proposed addition to your lumbar spine exam:
· Perform a PSLR
· Perform an ASLR
· Peform an ASLR with AB**
If the PSLR is (+) for radicular pain follow up with Braggard’s test and a well straight leg raise. If they’re positive as well, consider ordering a lumbar MRI. If the PSLR is (-) then perform an ASLR, if the ASLR is (+) for pain or radiating symptoms perform the ASLR with AB and see how the patient’s symptoms change. If the patient’s symptoms improve, then it’s likely they could benefit from some AB/Core stability training. If the patient’s symptoms don’t improve with AB, consider that the patient needs more mobility in their pelvis and thoracic spine in addition to more specific functional testing to delineate whether they have a motor control or tissue extensibility issue and refer accordingly.
**The goal of AB is for the patient to functionally stiffen their spine while maintaining normal respiration. Verbal cues (e.g. stiffen your abdominals or tighten your stomach) can be used to achieve this. Once the patient has attempted to brace you may introduce some perturbations (e.g. small nudges to the spine/pelvis in different directions) while they are encouraged to maintain the locked position.
There is much to be learned from functional testing of the lumbar spine and pelvis and it’s important to serve as a baseline for which therapeutic approaches to consider. The ASLR with and without AB is a simple test to consider with both your acute and chronic lumbar spine patients that will garner some great clinical information for how to proceed therapeutically.
While, I would like to think that we’re moving towards a more decisive diagnostic model as to what combination of therapies would best suit a patient for a particular presentation, in my humble opinion we’re still far from there. Having worked with many primary care physicians and neuromusculoskeletal specialists in different disciplines there is still a wide range of theories and general thoughts of what works when and for which patient. Moving towards a functional assessment model will help move us forward towards eliminating all the guesswork.
1. Cox JM. Low Back Pain: Mechanism, Diagnosis and Treatment. 5th ed. Baltimore: Williams & Wilkins, 1990: 380.
2. Cipriano JJ. Photographic Manual of Regional Orthopedic and Neurologic Tests. 2nd ed. Baltimore: Williams & Wilkins, 1991: 56.
3. Vera-Garcia FJ, Elvira JL, Brown SH, McGill SM. Effects of abdominal stabilization maneuvers on the control of spine motion and stability against sudden trunk perturbations. J Electromyogr Kinesiol 2007;17:556-557. Epub 2006 Sep 22.
4. Grenier SG, McGill SM. Quantification of lumbar stability using two different abdominal activation strategies. Arch Phys Med Rehabil 2007; 88:54-62.