Should we leverage the Lever Sign test to evaluate for anterior cruciate ligament (ACL) tears?

 Bottom Line: The Lever Sign test is reportedly 63-100% sensitive and 90-100% specific for ACL tears^1,2,3. More studies are needed, but initial results may point toward a new viable maneuver in evaluating ACL tears. To perform the Lever test, you have the patient fully extend their knee, place a closed fist under the proximal third of the calf, and, using the other hand, apply a downward force on the distal third of the quadriceps. A positive Lever test is when the foot does not raise off the examination table as the ACL is unable to counteract the downward force. Click this link for a good Youtube description summarizing some of the findings and explaining the test.

See the figure below for an example¹.

The Details

A 2014 Italian prospective study¹ by Lelli et. al recruited 400 patients with confirmed ACL ruptures on MRI in order to evaluate the new ACL physical examination maneuver they created. They appropriately excluded cartilage defects, multi-ligamentous injuries, meniscal injuries, and prior reconstructions of the affected ACL. The patients were equally split into 4 groups based on two factors: 1. complete vs. partial ACL lesion and 2. acute vs. chronic. The study then blinded 1 physician (unclear if it was Dr. Lelli) to the MRI results who performed the Lever Sign, Lachman, Anterior Drawer, and Pivot Shift tests on everyone. The uninjured leg was used as a control. The results were suspiciously positive with 100% sensitivity and 100% specificity. The closest sensitivity was 72% for the Anterior Drawer. See the table below for a summary of comparative accuracies of the different tests¹.

A Small Discussion

A few critiques have been made about the study and the authors concede them in the discussion section. The diagnosis of ACL tear was performed with a reliable and non-invasive test, the MRI - however, the gold standard is through arthroscopic visualization and that was not performed.

Additionally, the control group was the same as the test group. They just used the contralateral unaffected leg. And while it is helpful to have the same physician perform the maneuver to create homogeneity, it becomes impossible to determine inter-rater reliability. These maneuvers are all subjective and the results of one test can affect the subsequent tests the physician performs.

Another critique is the study started with a pre-selected population that had a diagnosed ACL tear. A better performing study would be to expand the population to those presenting with symptoms concerning for an ACL tear.

The final kicker is the study was performed by the creators of the test itself. While it is an inherent flaw for all studies that postulate a new diagnostic test, the significant results of 100% sensitivity and specificity should give us pause.

Subsequent Studies

After learning of the test, a group in Turkey published a 2015 “validation” study² utilizing arthroscopy as the gold standard prior to reconstructing their ACLs. They found that the Lever Sign test had a higher sensitivity than the currently preferred Lachman test.  It had a 94 and 98% sensitivity (pre and post anesthesia) compared to the Lachman, which had an 80 and 88% sensitivity, respectively.

The study methods are blurred, but essentially, they recruited 117 patients diagnosed with an ACL tear and performed the 4 tests (Lever Sign, Lachman, Anterior Drawer, and Pivot Shift) on the operating table pre and post-anesthesia. The exclusion criteria were similar to the original study. They used 2 physicians that resulted in a good inter-rater reliability of 0.82 to 0.96. This study certainly has a lot of limitations and only benefits by adding the dimension of confirming the tear arthroscopically.

In 2017, an American group from the Mayo Clinic in Arizona published a prospective study³ that broadened the patient demographic and challenged the Lever Sign test. They evaluated 102 patients with a chief complaint of acute knee pain with MRI as the reference standard. They found that the Lever Sign test had a whopping 63% sensitivity and 90% specificity compared to the Lachman which had a 90% sensitivity and 96% specificity.

The study split the cohort into surgical and non-surgical groups. The standard 4 tests were performed either on the operating table or the clinic for surgical and non-surgical, respectively. They used blinded providers of different training levels (undergraduate student, medical student, orthopaedic resident, orthopaedic fellow). It is unclear how they were educated on the test. The study did not find a significant difference in accuracy between the providers. However, they did not assess inter-rater reliability. The authors conceded this as a limitation as well as the lack of a control group. They do note that their concern with the Lever Sign test is that the fundamental concept has not been validated with a biomechanics study.

Final Thoughts

Although the jury is still out on the Lever Sign test, there are some promising results. None of the studies published so far should push any provider to claim that the Lever test is the best or that it should be discarded. More studies and discourse are needed. However, it is a simple and easy to understand maneuver that could serve as a future adjunct in your examination.

References:

1. Lelli, Alessandro, et al. "The “Lever Sign”: a new clinical test for the diagnosis of anterior cruciate ligament rupture." Knee Surgery, Sports Traumatology, Arthroscopy 24.9 (2016): 2794-2797.
2. Deveci, Alper, et al. "The arthroscopical and radiological corelation of lever sign test for the diagnosis of anterior cruciate ligament rupture." Springerplus 4.1 (2015): 830.
3. Jarbo, Keith A., et al. "Accuracy of the lever sign test in the diagnosis of anterior cruciate ligament injuries." Orthopaedic journal of sports medicine 5.10 (2017): 2325967117729809.

William Denq, M.D.