The “Lever Test,” or “Lelli’s Sign,” is a relatively new method devised to give us a quick and easy assessment of ACL integrity. What makes this test brilliant is its simplicity and reliance on the concept of using an intact ACL to demonstrate a simple fulcrum or “see-saw.” (Think back to your elementary school days to visualize a see-saw…)
If we look at a basic diagram of the femur and the tibia (see image), note that when the ACL becomes taut, it prevents the tibia bone from moving forward in relation to the femur. We can also say that the ACL keeps the femur from moving posterior on the tibia. (These two concepts are essentially the same; it really just depends on where the force is applied on the leg.)
The Lever Test is summarized as follows
1. Place the individual on a table with the leg flat and facing upwards.
2. The tester places his or her fist (or other object) under the shin of the subject, creating a fulcrum. Think of this as the see-saw with the fist acting as the pivot point.
3. The tester places a direct downward force on the femur, thus causing the slack in the ACL to be taken up and become taut.
4. If the ACL is intact and doing its job, the force placed down through the femur should cause the foot to come off the table, just as you would observe with a see-saw.
5. If the foot does not come off the table, this test should be performed on the other, uninvolved leg for comparison.
6. Note that in rare cases we will not get the foot to raise on either side even if there are intact ACL’s. These types of patients would be categorized as markedly “hyper-mobile” or having excessive mobility.
Take a look at the quick video of what we should see with a normal ACL. So easy!