K. Jeffrey Miller, DC, MBA
Most orthopedic and neurological tests are taught as individual entities. They are then grouped into regions and/or categories of pathology. Seldom are they taught in patterns or sequences that consider efficiency in performance or clinical use. There are a few exceptions to this: Bragard's test is almost always taught as an immediate follow-up to the straight-leg-raising (SLR) test, and Fajersztajn's test is almost always taught as an immediate follow-up to the crossed straight-leg-raising test (CSLR). These short sequences are effective, but they can be enhanced.
SLR and Bragard's tests are intended to detect radicular pathologies causing lower extremity pain. SLR is employed first to reproduce the pain of the chief complaint. Bragard's follows immediately after to confirm the SLR result. The SLR/Bragard's combination is usually considered diagnostic. However, there are a few instances in which they can miss the pathology they are intended to detect.
Most tests for radicular pathology typically use some combination of hip flexion and knee extension. Lasegue's test and SLR, for example, both use these maneuvers. The only difference in the tests is the order in which the maneuvers are performed. Lasegue's uses hip flexion first, followed by knee extension. SLR uses knee extension first, followed by hip flexion. This minor difference is the reason the names of the two tests are often used interchangeably.
Since Lasegue's and SLR both require hip flexion and knee extension to reproduce symptoms, it is logical that removing one of the movements would reduce symptoms. This would serve as a confirmatory test, just as Bragard's does. When using Lasegue's test, if symptoms produced by hip flexion and knee extension are reduced by flexing the knee back to its original position, the procedure is termed Lasegue's differential test.
Considering the above, SLR-Lasegue's, Bragard's and Lasegue's differential can be sequenced to improve clinical efficiency. This can be taken a step further by studying the mechanism of Bragard's test.
Bragard's test for radicular pathology and Homan's test for deep-vein thrombosis (DVT) both involve dorsiflexion of the foot. A second commonality is that the conditions these tests are intended to detect both cause pain in the lower leg and calf. This mandates differential diagnosis.
When the foot is dorsiflexed following SLR, reproducing lower leg and calf pain, the pain may be radicular or due to a DVT. Differential diagnosis can be accomplished by flexing the knee, as in the Lasegue's differential test, while maintaining the dorsiflexed position of the foot.
With flexion of the knee, tension in the nerve root is reduced. The dorsiflexed position of the foot does not elicit enough tension in the nerve tissue and symptoms should decrease. Flexing the knee would not affect a DVT and symptoms would persist.
Note that some authors recommend a quick, sudden dorsiflexion of the foot during Bragard's test. This is not recommended in practical assessment. The action may dislodge a DVT, making it subject to transport through the vascular system.
The sequence has now expanded to a series of four tests. The supine patient can be examined by raising the extended symptomatic leg to the point at which symptoms are reproduced. The leg is then lowered to just below the point symptoms were produced and the foot dorsiflexed. Reproduction of symptoms reinforces the initial SLR finding and is then followed by flexion of the knee while maintaining foot dorsiflexion.
Relief of symptoms with knee flexion further reinforces the SLR/Bragard's findings. Continued symptoms with knee flexion and continued dorsiflexion suggest the possibility of DVT. Moses' test (squeezing the calf muscles to reproduce the pain of DVT) is used as a confirmatory procedure when DVT is suspected. Squeeze cautiously to avoid dislodging the DVT.
Symptoms during SLR are typically produced between 35 and 70 degrees. Considering this, flexion of the knee for Lasegue's differential test should occur while maintaining the angle of hip flexion present when Bragard's test is performed. This allows the possibility of symptom relief and test interpretation without movement of the hip joint. Avoiding movement of the hip at this point is important, as it allows the sequence to expand further.
The "sign of the buttocks" test differentiates between radicular and hip joint pathologies. The test is performed by maintaining the position of the hip joint following a positive SLR. Flexing the knee (Lasegue's differential) and attempting to increase hip flexion provide the differential. If the hip flexes further, the condition is radicular/sciatic in nature. If the hip does not flex further, hip joint pathology is indicated. Hip joint pathology can be further evaluated by attempting to move the patient's leg into the figure-four position of Patrick's test.
The sequence has now expanded to a series of five tests. The supine patient can be examined by raising the extended symptomatic leg to the point at which symptoms are reproduced. The leg is then lowered just below the point symptoms were produced and the foot dorsiflexed. Reproduction of symptoms reinforces the initial SLR finding. This is followed by flexion of the knee while maintaining foot dorsiflexion. This position is held long enough to interpret results for Homan's test; the hip is then flexed further to complete the sequence with the sign of the buttocks maneuver.
The described sequence provides diagnostic information for identifying radicular problems, DVT and hip joint pathologies. The time spent performing the sequence is only seconds longer than the original SLR and Bragard's sequence. The result is improved efficiency and diagnostic information.
It is recommended that the reader study the tests listed here individually before using them in combination. After study of these and other tests, testing combinations will become more evident and their employment will enhance any examination.
