Guest Post: Dr. Michael Chivers, certified F.A.P. & F.R. Instructor discusses the prone Lachmans test
Physical examination of the knee involves assessing for the integrity of the cruciate and collateral ligaments. In the sports medicine setting the vast majority of non-contact knee injuries involve damage and tearing of the Anterior Cruciate Ligament (ACL).
The most common orthopaedic test for diagnosing tears of the ACL is the Lachman test. The medical evidence also suggests that the Lachman is the current gold standard test in the clinical setting due to its high levels of diagnostic accuracy.
During the Lachman test the examiner must stabilize the patient’s femur with one hand while attempting to translate the tibia forward with the other hand. The purpose of the test is to assess the quality of the “end feel” which is of the utmost importance in detecting the presence of ACL injury.
There are times when the size of the patient’s thigh is too large (or the examiner’s hands are too small) to allow for adequate stabilization of the femur, which makes this test difficult to perform.
During the last F.A.P lower limb seminar I demonstrated the Prone Lachman Test for assessing integrity of the ACL. By placing the patient prone it decreases the need for the examiner to stabilize the femur.
In the latest issue of JOSPT, Mulligan, Harwell and Robertson investigated the reliability and diagnostic accuracy of the Prone version of the Lachman test. In their investigation they found a sensitivity of 70% and a specificity of 97%, a positive predictive value of 94% and a negative predictive value of 80%. This is the first study to actually document the diagnostic accuracy of the Prone Lachman test, which interestingly enough has very similar accuracy and reliability as its predecessor the Lachman test.