Lateral compartment translation predicts the grade of pivot shift: a cadaveric and clinical analysis

Abstract

Anterior translation of the lateral compartment was hypothesized to correlate with the clinical grade of a pivot shift maneuver. Using a computer-assisted navigation system, this hypothesis was tested by recording the maximum anterior tibial translation in the medial and lateral compartment as well as the arc of rotation during the pivot shift maneuver. One hundred and fifty-four pivot shift examinations were performed on cadavers with various degrees of instability, and 24 pivot shift exams were performed on patients under anesthesia before and after ACL reconstruction. In all positive pivot shift exams, anterior tibial translations were found to be higher on in the lateral compartment compared to the medial compartment. In addition, an excellent correlation was found between the amount of lateral compartment translation and the clinical grade of the pivot shift; medial compartment translations and amount of knee rotation could not distinguish between clinical grades. Finally, a threshold of 6-7 mm of anterior tibial translation in the lateral compartment was necessary to produce a positive pivot shift. Taken together, these data suggest that monitoring lateral compartment translations during a pivot shift exam may be a convenient means to evaluate the outcomes of ACL surgery and that requisite increases in anterior translation of the lateral compartment are necessary for each progressive clinical grade of the pivot shift examination.

Basic biomechanic principles of knee instability

“…A good correlation between a-p translation of the lateral compartment and the results of the clinical pivot shift test grade as shown are the basis for image analysis software [17] (Fig. 2).…”

“…During the pivot shift maneuver, the anterior tibial translation of the lateral compartment exceeds the motion in the medial compartment. This translation has been shown to correlate with clinical grading of the pivot shift [17], making the objective quantification of this translation clinically significant. For the purpose of objective quantification of the pivot shift in both in vivo and in vitro settings, a variety of methods have been identified and described.…”

“…After the first historical description of the test by Galway and MacIntosh [30], many other variations have been described by physicians and researchers [31][32][33]. However, research has documented that the interpretation of the pivot shift test remains subjective and examiner dependent [17,[34][35][36][37]. The attempt of quantifying the pivot shift test has proven difficult given the multiple techniques for the exam and the associated large variation in kinematics [37].…”

Posterior Cruciate Ligament and Posterolateral Corner Deficiency Results in a Reverse Pivot Shift

“…Customized software allowed us to compare the motion path during the pivot shift with the reference motion path of extension-flexion [9,22]. We reported the maximum tibial translations and rotation during the RPS maneuver as the difference between reference motion path and RPS motion path in the medial and lateral compartments [5]. The utilization of a surgical navigation system during clinical laxity examinations was both reliable and repeatable [34].…”

Kinematic outcomes following ACL reconstruction

“…During the pivot shift maneuver, the anterior tibial translation of the lateral compartment exceeds the motion in the medial compartment and correlates with the grading of the pivot shift [125]. Based on this finding, the image analysis principle attempts to gauge anterior tibial translation of the lateral compartment using skin markers attached to the bony landmarks lateral epicondyle, Gerdy's tubercle, and the fibular head (see Fig.…”