Posterior Sag Test: How to Check for PCL Tear

The Posterior Sag Test, often called Godfrey's Test, is a simple observational test used by physiotherapists to assess the integrity of the Posterior Cruciate Ligament (PCL) using gravity.

1. Purpose

The primary purpose of the Posterior Sag Test (also known as Godfrey's Test) is to **test for** the integrity of the Posterior Cruciate Ligament (PCL). It is a visual observation test to see if gravity pulls the tibia backwards.

2. How to Perform

1. The patient is positioned in supine (lying on their back).
2. The patient's hip is flexed to 45 degrees and the knee is flexed to 90 degrees.
3. The examiner ensures the patient's muscles (quadriceps) are completely relaxed.
4. The examiner views the knee from the side (lateral aspect) to observe the position of the tibia relative to the femur.

3. Positive & Negative Sign

Positive Sign (Test is POSITIVE):
A positive test (indicating a PCL tear) is:

• The proximal tibia "sags" or drops posteriorly due to gravity.
• There is a loss of the normal "step-off" (the tibial tuberosity should normally be anterior to the distal femur).

Negative Sign (Test is NEGATIVE):
A negative test is when the tibial tuberosity remains visibly anterior to the femur (a normal step-off is present).