The Pivot Shift Test is a physical examination used to evaluate the stability of the knee joint, particularly to diagnose an anterior cruciate ligament (ACL) rupture.
The pivot shift is theoretically the best test to dynamically assess the knee’s ligamentous condition, which is particularly important in identifying ACL deficiency, assessing reconstructive procedures, and developing treatment plans for patients who have suffered an ACL injury. Currently, the pivot shift test is the most effective clinical test for identifying ACL rupture.
With growing evidence that pivot shift is an ideal test to dynamically evaluate ligamentous status of the knee, it’s important to discuss the current status of pivot shift methodology, and its interpretation in terms of grading and clinical reliability. Let’s explore this pivotal examination.
Significance of Pivot Shift Test
Pivot shift test is an essential clinical evaluation used to identify injuries compromising the stability of the knee. It primarily focuses on the anterior cruciate ligament (ACL) injury. The ACL is a key ligament that limits the tibia’s (the shin bone) excessive forward movement and rotation with respect to the femur (the thigh bone). ACL injuries can cause the knee to become unstable, which increases the risk of further damage.
The pivot shift test is used in 85% of research evaluating clinical outcomes following ACL repair, confirming its significance in determining a patient’s continued functional instability after surgery.
Must read Life After ACL Surgery before you proceed.
What Are The Main Components Of The Pivot Shift Test?
A pivot shift can be employed to evaluate the combined tibio-femoral internal rotation and anterior tibial translation when the ACL is injured. This test has two primary components:
- translation – anterior subluxation of the lateral tibial plateau
- rotation – rotation of the tibia relative to the femur
It checks for instability, which is a key factor in determining how well the knee will work. In reality, it is instability rather than just the anterior cruciate ligament injury- that puts the menisci at future risk, and gives the sensation that the “knee is not secure”.
How to Perform Pivot Shift Test?
The pivot shift can be intrinsically challenging to perform. Significant variability exists between different examiners. The most frequently cited method for pivot shift is: to flex the knee from 0° (full extension) to 90° of knee flexion while exerting external rotation stresses on the tibia and a valgus stress to the knee.
The patient is positioned in a calm, supine position during the test. The test knee should be fully extended and the hip should be flexed to around 30 degrees. The heel of the leg being evaluated is held in one of the examiners’ hands. The other hand of the examiner is on the lateral aspect of the proximal tibia, with the fifth metacarpal close to the head of the fibula.
The examiner starts with the lower leg in internal rotation and slowly flexes the knee while applying a moderate amount of valgus and internal rotation stress to the proximal tibia.
If the proximal tibia is subluxated anteriorly on the distal femur at roughly 30 degrees of flexion, the test is considered positive. In a positive test, the knee will extend again as the proximal tibia clunks back into place. Due to the iliotibial band, flexion beyond around 40 degrees will also cause the tibia to shorten.
When performed properly, the pivot shift test is quite accurate. However, because the movement stimulates instability, it may be challenging for the person being tested to relax as much as is necessary throughout this examination. For a thorough understanding watch this video: Pivot Shift Test | Anterior Cruciate Ligament (ACL) Rupture Knee.
Pivot Shift Test Interpretation
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Pivot Shift Test Grading
- grade 0 (normal),
- grade 1 (glide),
- grade 2 (clunk),
- grade 3 (locked subluxation)
Grade I pivot shift
There is an abnormal movement that can be felt as a tiny and gradual sliding reduction when the tibia is kept in maximum medial rotation. This doesn’t happen during lateral or neutral rotation. It should be noted that it is hardly noticeable when the patient is awake but clearer when he is unconscious. Residual laxity or partial cruciate damage causes a grade I knee. As a result, there is mostly anterolateral instability.
Grade II pivot shift
When the tibia is medially rotated, there is a noticeable “clunk,” and when it is in the neutral position, there is an abnormal movement. When the tibia is held in a posture of clear lateral rotation, the test is negative. The grade I and grade II can be distinguished by the clunk and the abnormal movement in a neutral position. Due to a non-functioning ACL, a grade II knee has a more visible anterior instability. This grade of pivot shift occurs in moderately severe chronic instability as well as in a fresh, “isolated,” anterior cruciate ligament rupture
Grade III pivot shift
The tibia moves abnormally with a loud clunk when it is held in neutral or moderate lateral rotation. The tibia may move along this path to reach its greatest anterior laxity. The tibia is positioned anteriorly translated with a lateral rotation, while the femur descends posteriorly as a result of gravity. The shift is less noticeable when there is a medial rotation. We discover a grade III pivot shift in an acutely injured knee with moderate to severe damage to the posteromedial and posterolateral components, including a full anterior cruciate rupture. This also holds when the knee has substantial chronic instability, which causes the secondary posterior restraints to stretch.
Is the Pivot Shift Test a Reliable Test?
The Pivot Shift test attempts to reproduce the rotational and translatory instability found in a knee with a damaged ACL. For detecting an ACL tear, the test has a sensitivity range of 0.18 to 0.48 and a specificity range of 0.97 to 0.99. The average sensitivity and specificity are 0.32 and 0.98, respectively.
Although the test is clinically useful and reproduces a functional movement of the knee joint, it is challenging to quantify. A navigation system was recently used in research to quantify assessments of knee laxity in people who had ACL reconstruction. The Pivot Shift Test was accurate in assessing surgical performance and patient self-assessment of laxity. This highlights the test’s clinical applicability. Lachman test or Anterior drawer test have historically been used more frequently to assess knee laxity, due to their quantifiability. However, recent technological advancements have made it possible to observe the pivot shift’s motions more objectively and quantitatively, which may eventually allow for the test to be quantified for research
Arrange a Healthcare Consultation
If you are concerned about your knee stability, speak with a medical expert who can do this test and come up with an appropriate treatment strategy for you. A team of experts at Hip & Knee Orthopaedics is available to evaluate your knee ligament status and offer advice.