What constitutes a positive SAG (Godfrey’s) test?

• A. Displacement of the tibial tuberosities greater on the involved leg when both hips and knees are flexed to 90 degrees.
• B. Displacement greater on the non-involved leg.
• C. End-feel changes during knee extension.
• D. Pain with hip rotation.

Answer: (A)

The sign detects posterior sag of the tibia, which points to a posterior cruciate ligament (PCL) injury. With the patient lying on the back and both hips and knees flexed to 90 degrees, gravity can pull the tibia backward if the PCL is compromised. A positive Godfrey’s test is when the tibial tuberosities are not level, with the tibia on the involved leg sagging posteriorly (the tuberosity sits lower) compared with the opposite leg. This posterior translation reflects loss of PCL restraint. The other ideas don’t fit: displacement on the non-involved leg would not indicate a PCL tear, end-feel changes during knee extension aren’t what this test measures, and pain with hip rotation points to a hip issue rather than a knee PCL sign.