The lever test is a physical examination maneuver used to assess for anterior cruciate ligament (ACL) ruptures in the knee.
Here's a breakdown of how the lever test is performed and interpreted:
How the Lever Test is Performed:
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Patient Positioning: The patient lies on their back (supine) with their knee fully extended and their heel resting on the examination table.
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Examiner's Hand Placement: The examiner places a clenched fist or a fulcrum under the patient's proximal calf, just below the tibial tuberosity (the bony bump at the front of the shin bone, just below the knee).
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Applying Pressure: The examiner applies gentle downward pressure on the quadriceps tendon, which is located just above the kneecap (patella).
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Observation: The examiner observes the patient's heel. The key is to see if the heel lifts off the table during the downward pressure on the quadriceps tendon.
Interpreting the Results:
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Positive Lever Test (Indicative of ACL Rupture): If the ACL is intact, applying downward pressure on the quadriceps tendon should cause the leg to lift off the table as a unit from the point of the fulcrum. If the ACL is torn or deficient, the heel will not lift off the table. The leg will not move as a single unit because the ACL is not there to effectively transmit the force along the tibia.
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Negative Lever Test (ACL Likely Intact): If the heel lifts off the table, it suggests the ACL is likely intact and able to transmit force effectively.
Important Considerations:
- The lever test is just one component of a comprehensive knee examination. It should be used in conjunction with other tests and the patient's history to make an accurate diagnosis.
- Relaxation is crucial for accurate assessment. An anxious or tense patient may produce a false negative.
- The sensitivity and specificity of the lever test can vary, and other tests like the Lachman test and the anterior drawer test are often used as well.
- It's important to consider the patient's overall clinical picture, including mechanism of injury, symptoms, and other examination findings.
