Understanding the Lachman Test Assessment
The **most sensitive** clinical test for detecting a tear of the **Anterior Cruciate Ligament (ACL)**.
Watch How It's Done
How do I start?
Patient is supine. Knee is positioned in **20° to 30° of flexion** (a non-guarding position).
What happens?
The examiner stabilizes the femur with one hand and applies an **anterior translation force** (pulling forward) to the proximal tibia with the other hand.
In Plain English
What Does a Positive Result Mean?
**Excessive anterior translation** of the tibia compared to the unaffected side, or a **'soft' or 'mushy' endpoint** (loss of firm endpoint), indicating an ACL tear.
Helpful Tip:
The test's position minimizes hamstring involvement, improving sensitivity. Grading is based on the amount of translation (e.g., Grade I, II, III).
Safety First
This guide is to help you understand what happens in a clinic. Do not try to diagnose yourself. If you have severe pain, swelling, or cannot put weight on your leg, please visit an urgent care center or your doctor immediately.
Other Knee Tests
Pivot Shift Test
To dynamically assess for **anterolateral rotatory instability** of the knee, which is highly indicative of a **complete ACL tear**.
Posterior Drawer Test of the Knee
To assess the integrity of the **Posterior Cruciate Ligament (PCL)**.
Posterior Sag Sign (Gravity Drawer Test)
To detect a rupture of the **Posterior Cruciate Ligament (PCL)** by observing the effect of gravity.
Slocum Test (Anterolateral Rotatory Instability)
To assess for **anterolateral rotatory instability** and the function of the **Anterolateral Ligament** (a dynamic variant of the Anterior Drawer).