The Duck Walk Test, sometimes referred to as the Childress Test, is a common maneuver used by healthcare providers to evaluate the knee joint during an orthopedic physical examination. This non-invasive screening tool is performed as a weight-bearing provocation test designed to assess the knee’s stability and function under a high degree of flexion. Its application is generally reserved for patients presenting with symptoms of an internal knee derangement, particularly after an injury or the onset of joint-line pain.
How the Test is Performed
The procedure for the Duck Walk Test begins with the patient standing and then assuming a deep, full squatting position. Once the patient has achieved this deep squat, the examiner asks them to begin “waddling,” or walking in this low position.
The patient is typically instructed to waddle a short distance, moving forward, backward, and sometimes side-to-side. This movement requires the patient to actively rotate the tibia (shin bone) internally and externally relative to the femur (thigh bone) while the joint is under a significant axial load. The examiner closely observes the patient throughout the maneuver, noting any hesitation, instability, or visible signs of pain.
Conditions Screened by the Duck Walk Test
The anatomical focus of the Duck Walk Test is the menisci, which are C-shaped cartilage pads between the femur and the tibia. The original formulation of this maneuver was specifically intended to detect lesions in the posterior third of the medial meniscus, a location that can be difficult to assess with other methods. The deep squat position forces the femur to compress the menisci against the tibia, effectively trapping and stressing the posterior horns of these structures.
The waddling motion then causes an active rotation of the lower leg, which applies a shearing and twisting force to the meniscal tissue. This mechanical stress serves to provoke symptoms in patients who have a meniscal tear, whether it is located medially (inner knee) or laterally (outer knee). While initially focused on the medial side, studies have shown the test is used to screen for meniscal tears throughout the knee joint, including both anterior and posterior horns.
Interpreting the Test Results
A “positive” result for the Duck Walk Test is determined by the patient’s reaction and the physical findings observed by the practitioner. The inability to achieve or maintain the full squat is one immediate sign of a positive test, suggesting severe pain or restriction. A positive result also occurs if the patient reports sharp pain, experiences a painful snapping sensation, or if the examiner feels a distinct click along the joint line during the waddling motion.
The location of the pain can offer further insight, as pain reported on the inner side of the knee (medial joint line) suggests a potential medial meniscal tear, while pain on the outer side (lateral joint line) points toward a lateral meniscal tear. The test found to have a sensitivity of 71% but a low specificity of 39% for detecting meniscal tears. The Duck Walk Test is viewed as a useful screening tool to decide if further, more advanced imaging like an MRI is necessary, rather than serving as a definitive diagnosis on its own.