Lever Sign – A Better ACL Exam Technique
January 28, 2020
Written by Vivian Lei
Compared to other clinical tests of anterior cruciate ligament (ACL) disruption, the lever sign is more accurate and sensitive in an ED setting.
Why does this matter?
Accurate initial diagnosis of ACL rupture can facilitate timely follow-up and repair. This study shows increased sensitivity for ACL rupture with the lever sign test and can be a helpful addition to the standard knee injury examination in the ED.
The power of a lever
This was a single-center implementation study in which emergency physicians were trained in performing the lever test. They enrolled 45 patients between the ages of 12 and 55 who presented to the ED with acute knee injuries. Patients were diagnosed as having ACL rupture or not with the lever sign test during the first 4.5 months of the study and either the anterior drawer or the Lachman test for the second 4.5 months of the study. Follow-up MRI imaging was used as the gold standard. The lever sign test was found to be 95% accurate and 100% sensitive for ACL rupture. Anterior drawer/Lachman testing was 88% accurate and 40% sensitive. Specificity was slightly higher for the anterior drawer/Lachman testing at 100% vs. 94% for the lever sign. Diagnostic confidence was slightly higher for the lever test and there did not appear to be any difference in accuracy based on training level of the provider.
Here is how to do it!
How to perform the lever sign test:
The patient is placed supine with the knees fully extended on the examination table.
The examiner places a closed fist under the tibial tuberosity of the affected knee. This causes the knee to flex slightly. (Pro tip – make sure your fist isn’t too close to the knee, or it won’t work.)
With the other hand, the examiner applies moderate downward force to the distal femur. With this configuration, the patient’s leg acts as a lever over a fulcrum—the clinician’s fist.
Intact ACL = Patient’s foot will rise off the bed with the addition of downward force to the distal quadriceps.
Ruptured ACL = Patient’s foot will remain in contact with the bed with addition of downward force to the distal quadriceps.
Implementing the Lever Sign in the Emergency Department: Does it Assist in Acute Anterior Cruciate Ligament Rupture Diagnosis? A Pilot Study. J Emerg Med. 2019 Dec;57(6):805-811. doi: 10.1016/j.jemermed.2019.09.003. Epub 2019 Nov 7.
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