Daily Bolus of LR: Lachman test in ACL injury

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April 19, 2011 by dailybolusoflr

 Dear all::

 

My apologies…apparently my BOLUS distribution list was somehow deleted and yesterday’s email was sitting in my outbox.  So, here it is!

 

Lachman Test

 

This is an examination which is thought to be have a higher positive predictive value for diagnosis of an anterior cruciate ligament injury (ACL) than the anterior drawer test (about 60% vs 30%)

 

To perform the test:

1.       Place the knee in about 15-20 degrees of flexion with a small amount of external rotation at the hip

2.       Grasp the inner aspect of the calf with one hand and the outer aspect of the distal thigh with the other

3.       Attempt to move the tibia forward in relationship to the knee

4.       Comparison should be made between the affected knee and the normal knee

5.       Consideration should be given to how many mm of laxity greater the affected side has as well as whether or not the endpoint is hard or soft.  (hard implies it is taught like a rope would be taught when stretched to its full length vs soft, which is more like an elastic band)

 

Degree of laxity

·         mild: 0 to 5 mm laxity (greater than the uninvolved side)

·         moderate: 6 to 10 mm laxity (greater than the uninvolved side)

·         severe: 11 to 15 mm laxity (greater than the uninvolved side)

o   when exam reveals such a large amount of movement always consider other concurrent ligamentous injuries such as the MCL or meninscus

 

Diagnosis is considered highly suspected when there is greater than 11 mm of anterior movement of the injured side or greater than 3 mm compared to the normal side.

 

Note: Following ACL reconstruction, laxity should be less than 3 mm compared to opposite side

 

 

 

To view how to perform this exam:

http://www.youtube.com/watch?v=dH_jnTy1rNk

 

 

 

Linda Regan, MD FACEP

Program Director, Emergency Medicine Residency

Johns Hopkins Medical Institutions

 

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