Posterior Drawer Test vs. Posterior Sag Sign

Attribute	Posterior Drawer Test	Posterior Sag Sign
Test for	Posterior cruciate ligament (PCL) injury	Posterior cruciate ligament (PCL) injury
Position of patient	Supine with knee flexed at 90 degrees	Supine with knee flexed at 90 degrees
Technique	Grasping the tibia and pushing it posteriorly	Grasping the tibia and observing for posterior sag
Positive sign	Increased posterior translation of tibia	Posterior sag of tibia
Indicates	PCL injury	PCL injury

Introduction

When it comes to assessing the integrity of the posterior cruciate ligament (PCL) in the knee, two commonly used tests are the Posterior Drawer Test and the Posterior Sag Sign. Both tests are used by healthcare professionals to evaluate the stability of the knee joint and determine the presence of any ligamentous injuries. While both tests aim to assess the same ligament, they differ in their techniques and interpretations. In this article, we will compare the attributes of the Posterior Drawer Test and the Posterior Sag Sign to understand their similarities and differences.

Posterior Drawer Test

The Posterior Drawer Test is a physical examination maneuver used to assess the integrity of the PCL in the knee joint. During the test, the patient lies supine with the knee flexed at 90 degrees. The examiner stabilizes the distal thigh with one hand while grasping the proximal tibia with the other hand. The examiner then applies a posteriorly directed force to the tibia while assessing for any abnormal posterior translation of the tibia relative to the femur. A positive test is indicated by increased posterior translation compared to the unaffected knee, suggesting PCL laxity or injury.

Posterior Sag Sign

The Posterior Sag Sign, also known as the Godfrey Test, is another physical examination maneuver used to evaluate the integrity of the PCL in the knee joint. During the test, the patient lies supine with both hips and knees flexed to 90 degrees. The examiner observes the position of the tibial tubercle relative to the femoral condyles. In a positive test, the tibial tubercle will sag posteriorly or inferiorly compared to the unaffected knee, indicating PCL laxity or injury. The Posterior Sag Sign is considered positive when there is a visible step-off or drop of the tibial tubercle.

Comparison of Techniques

While both the Posterior Drawer Test and the Posterior Sag Sign aim to assess the integrity of the PCL, they differ in their techniques. The Posterior Drawer Test involves applying a posteriorly directed force to the tibia to assess for abnormal posterior translation, while the Posterior Sag Sign relies on visual observation of the position of the tibial tubercle relative to the femoral condyles. The Posterior Drawer Test is more of a manual stress test, whereas the Posterior Sag Sign is a passive test that relies on gravity to demonstrate PCL laxity.

Interpretation of Results

Interpreting the results of the Posterior Drawer Test and the Posterior Sag Sign requires a keen understanding of the anatomy and biomechanics of the knee joint. A positive Posterior Drawer Test indicates increased posterior translation of the tibia relative to the femur, suggesting PCL laxity or injury. On the other hand, a positive Posterior Sag Sign demonstrates a visible sag or drop of the tibial tubercle, also indicating PCL laxity or injury. Both tests are indicative of PCL pathology, but they provide slightly different information based on their techniques.

Clinical Utility

Both the Posterior Drawer Test and the Posterior Sag Sign are valuable tools in the assessment of PCL injuries in the knee joint. The Posterior Drawer Test is more commonly used in clinical practice due to its simplicity and ease of administration. It provides a quantitative measure of PCL laxity by assessing the amount of posterior translation of the tibia. On the other hand, the Posterior Sag Sign is a useful adjunct test that can be performed quickly and easily in conjunction with other knee examination maneuvers. It provides a qualitative assessment of PCL laxity based on the position of the tibial tubercle.

Conclusion

In conclusion, the Posterior Drawer Test and the Posterior Sag Sign are two valuable tests used to assess the integrity of the PCL in the knee joint. While both tests aim to evaluate PCL laxity or injury, they differ in their techniques and interpretations. The Posterior Drawer Test involves applying a posteriorly directed force to the tibia, while the Posterior Sag Sign relies on visual observation of the position of the tibial tubercle. Both tests have their own clinical utility and can provide valuable information in the evaluation of knee injuries. Healthcare professionals should be familiar with both tests and their indications to make accurate diagnoses and treatment decisions for patients with PCL pathology.