Posterior drawer sign

Posterior Drawer Sign is a clinical test used in the evaluation of the integrity of the posterior cruciate ligament (PCL) in the knee. The PCL is one of the key ligaments that stabilize the knee joint, and it prevents the tibia (shin bone) from moving backwards relative to the femur (thigh bone). The posterior drawer sign is an important diagnostic tool for physicians and physiotherapists to assess potential damage to the PCL, which can occur due to trauma, sports injuries, or in association with other knee injuries.

Procedure

The test is performed with the patient lying on their back (supine position) with the knee flexed at 90 degrees. The examiner sits on the foot of the patient to stabilize it and then places both hands around the upper part of the tibia. A gentle posterior force is applied to the tibia, attempting to "draw" it backward. The amount of posterior translation (movement) of the tibia relative to the femur is assessed and compared to the uninjured knee.

Interpretation

A positive posterior drawer sign is indicated by an increased amount of posterior movement of the tibia compared to the normal or uninjured side. This suggests a tear or laxity in the PCL. However, the test's sensitivity and specificity can vary, and results should be interpreted in the context of the patient's history and other clinical findings.

Clinical Significance

The integrity of the PCL is crucial for the stability of the knee joint, especially in activities that involve running, jumping, or sudden changes in direction. A damaged PCL can lead to knee instability, increased risk of other knee injuries, and long-term degenerative changes within the joint. Early and accurate diagnosis using the posterior drawer sign and other tests can facilitate appropriate management, which may include physiotherapy, bracing, or surgical intervention.

Related Tests

Other clinical tests for assessing the PCL include the Pivot Shift Test and the Lachman Test, although the latter is more commonly used to evaluate the anterior cruciate ligament (ACL). Imaging studies such as MRI can also provide detailed information about the extent of PCL injury.