Lachman's test

Question 1

What does Lachman’s test diagnose?

Answer 1

ACL injury

Question 2

What’s the rationale behind Lachman’s test?

Answer 2

By applying a swift PA force on the tibia, you can test the ACL without the patient tensing hamstrings which would restrict this movement. It eliminates the subconscious expectation of movement so you get a valid result.

Question 3

What does a positive result indicate?

Answer 3

ACL injury / rupture

Question 4

Procedure of Lachman’s test

Answer 4

1) Explain & IC
2) Patient in long sitting / supine with knee flexed to 15-20 degrees - can use physio’s knee or a towel to support position
3) Physio stables the femur and holds the calf below the joint line
4) Ensure quads & hamstrings are relaxed
5) Physio pulls calf forward quickly in a “jerk” movement
6) Observe movement & end feel & compare to other side

Question 5

What is a positive result of Lachman’s test?

Answer 5

A soft end feel to the anterior translation / excessive anterior
translation compared to the non-affected knee
There may be a rupture of the ACL

Question 6

What is a negative result of Lachman’s test?

Answer 6

Equal translation of the tibia from the non-affected knee to the affected knee, and a hard end feel to the anterior translation movement

Question 7

Result: Soft end feel & excessive translation.
What does this mean?

Answer 7

ACL rupture

Question 8

What test should you do before Lachman’s and why?

Answer 8

Posterior sag sign test to rule out a PCL rupture as this would cause a false positive result of Lachman’s test.