Pivot Shift test of knee joint

Introduction

Pivot shift test is theoretically an ideal test for dynamic evaluation of the condition of the knee ligaments, which is particularly important in the diagnosis of ACL tear, the evaluation of reconstruction methods, and the formulation of treatment algorithms for patients with ACL injury. Currently, the pivot shift test is the most accurate clinical test to detect an ACL injury. An inverse displacement standardization method was described and shown to have improved accuracy.

However, many studies use alternative methods to test and quantify pivot bias. Thus, the pivot shift has been the subject of great research interest in recent years. Studies have shown that the phenomenon of torsional dislocation is multifactorial and that a high-grade torsional dislocation is usually associated with a secondary injury in addition to the ACL.

An incomplete understanding of the causes of rotation changes the treatment approaches and encourages surgeons to use additional reconstructive techniques, such as anterolateral complex treatment (ACL), without recognizing the true nature of the pathology. The purpose of this review is to discuss the current status and clinical utility of pivot motion techniques as they relate to ACL tears and related injuries.

Definition/Description

The pivot shift is a dynamic but passive test of knee stability performed by the examiner without patient intervention. This indicates an imbalance between the movement and gliding of the knee joint. The patient lies on his back. Displacement is a combination of axial load and light force applied by the examiner during flexion of the knee from an extended position. If the test is positive, it indicates damage to the anterior cruciate ligament.

Clinically important anatomical structure of the Knee joint

The knee joint is the human body’s biggest and most complicated joint. It is formed by the distal end of the femur and the proximal end of the tibia. Between the two lie the medial and lateral menisci. The front part of the femur (facies patellar femoris) articulates with the patella, which forms the patellofemoral joint.

The cruciate ligaments and collateral ligaments located in the condylar space are important ligaments of the knee. The anterior cruciate ligament (ACL) connects the anterior region of the intercondylaris to the medial part of the lateral cruciate ligament. This ligament extends from the tibial plateau upwards, dorsally and laterally. This prevents ventral movement of the tibia. The posterior cruciate ligament (PCL) connects the posterior region of the intercondylar to the lateral aspect of the medial femoral joint. The PCL runs medially, straight up, and just onward. The PCL prevents posterior instability of the knee joint, which means that the tibia does not move backward.

The PCL is stronger than the ACL. Both cruciate ligaments run in a twisting manner. it stabilizes the knee in the sagittal plane. When the knee is in end rotation, the cruciate ligaments are extremely crossed. Getting excited, they run more parallel. The cruciate ligaments are located mainly at the back of the joint capsule, so bending and stretching is not an obstacle.

Purpose

The purpose of this test is to detect anterolateral rotational instability of the knee. Structures that may be affected if this test is positive include the ACL, LCL, posterolateral capsule, arcuate complex, and iliotibial band (ITB).

Technique

The patient lies on his back with his legs relaxed. The examiner holds the heel of the examined leg with the examiner’s opposite hand, which is placed laterally on the proximal tibia distal to the knee.

The examiner then applies lateral tension and axial loading while internally rotating the tibia as the knee is moved from full extension to flexion. A positive test is indicated by subluxation of the tibia as the femur rotates outward, after which the tibia is reduced to 30-40 degrees of flexion.

Key studies

Is the pivot shift test a reliable test?

The Pivot Shift test attempts to replicate the rotational and translational instability of the ACL injury of the knee. The test has a sensitivity of 0.18-0.48 and a specificity of 0.97-0.99 for diagnosing an ACL tear. The average sensitivity and specificity are 0.32 and 0.98, respectively. Although the test is clinically relevant and reproduces the functional movement of the knee joint, it is difficult to quantify.

A recent study used a navigation system to measure knee laxity in people undergoing ACL reconstruction. The reverse shift test was reliable for both patient self-report of relaxation and surgical performance. This emphasizes the clinical importance of the test. Traditionally, the Lachman test or the less prominent anterior drawer test was more often used to measure knee laxity due to its quantification, but recent advances in technology have allowed a more objective and measurable observation of movements associated with rotational displacement and can lead to the ability. make the test quantitative for research purposes.

Grading the pivot shift

It has also been mentioned that there are many different versions of the fundamental pivot shift test(Losee, Johnson, and Southwick 1978; Galaway and MacIntosh 1980; Hugston et al. 1976; Slocum et al. 1976). All of these variations relate to forward translation and rotation of the pivot point at the femoral tibia.
In the reverse shear test, the scientist applies an axial and beam load with one hand.

This arm also controls the rotational position of the tibia during the test. On the other hand, the leg is held firmly against the examiner. The test can be performed in three rotational positions: medial, neutral, and lateral rotation of the tibia.

The pivot shift test results vary depending on the rotation.
Grade I dislocation: When the tibia is held in maximum medial rotation, an abnormal motion occurs that can be felt as a small, slight slip. This does not happen in free or side spin. A comment on this is that it is barely palpable when the patient is awake, but more obvious under general anesthesia. A grade I knee is the result of a sprain or partial cruciate injury. The result is instability, which is mainly anterolateral.

Grade II dislocation: The tibia is clearly rotated into the central position and there is abnormal movement in the neutral position. The test is negative if the tibia is held in a position where the direction of rotation is clear. A difference between grade I and grade II can be observed due to impingement and abnormal movement in the neutral position. Second-degree knee is more pronounced anterior instability due to a dysfunctional ACL. This joint movement is seen after a fresh “isolated” tear of the anterior cruciate ligaments and with chronic moderate instability.

Grade III dislocation: When the tibia is held in a neutral or moderate lateral position, there is an abnormal movement. The tibia can follow its path to maximum anterior laxity. Under the influence of gravity, the femur falls backward and the tibia is in an anterior position with lateral rotation.

In medial rotation, the change is less obvious. In an acutely injured knee with moderate to severe damage to the posteromedial and posterolateral structures, including a complete anterior border tear, a grade III torsional dislocation is seen. This also applies to severe chronic instability of the knee and subsequent straining of the secondary posterior attachments.

The table shows the medial and lateral in-plane motion of the knee compared to the injured knee of varying severity according to the pivot motion test.

The advantage of repeating the test in different rotational positions is that it provides a more accurate and reproducible way to specify the volume of the test, as opposed to a subjective assessment of severity. However, the disadvantage of this method is that it is not completely objective, because the examiner has to decide whether or not the turn shift test is positive. Except for the III value, there is a significant positive difference in test accuracy when evaluated under anesthesia.

Even under anesthesia, differentiating between classes II and III can be difficult. Such cases should be treated as Class II. The previous tourist connection is already non-functional from the II level. The difference between Class II and Class III is that if you have Class III, both the medial and lateral sides are looser.

This includes a secondary restriction to the posteromedial and posterolateral angles, along with purely lateral and medial structures. Some types of sharp injuries can be difficult to assess and additional evidence of a complete tear of the anterior cruciate ligament is required. The Lachman test can give a clear score and show that the tibial plateau is a subluxation.

The Lachman test can be performed on a painful knee. This does not apply to the turn shift test.

Clinical background

The importance of the test in determining clinical significance is that the different grades of the test can determine the level and direction of relaxation, which has been called anteromedial, anterolateral, and posterolateral. This results in visualization of the progression of a chronic anterior cruciate injury. This is due to the consecutive use of three positions of the tibia.

FAQ

Reference

Pivot Shift. (n.d.). Physiopedia. https://www.physio-pedia.com/Pivot_Shift
Pivot-shift test. (2022, April 21). In Wikipedia. https://en.wikipedia.org/wiki/Pivot-shift_test
Ladva, V. (2023, July 23). Lateral Pivot shift test. Mobile Physiotherapy Clinic. https://mobilephysiotherapyclinic.in/lateral-pivot-shift-test/