2015 ISAKOS Biennial Congress ePoster #1311

Quantitative Evaluation of the Pivot Shift – Relationship to Clinical Pivot Shift Grade: A Prospective International Multicenter Study

Yuichi Hoshino, MD, PhD, Kobe, Hyogo JAPAN
Ryosuke Kuroda, MD, PhD, Kobe, Hyogo JAPAN
Volker Musahl, MD, Pittsburgh, PA UNITED STATES
James J. Irrgang, PT, PhD, FAPTA, Pittsburgh, PA UNITED STATES
Nicola Francesco Lopomo, PhD, MSc Eng, Bologna ITALY
Stefano Zaffagnini, MD, Prof., Bologna ITALY
Jon Karlsson, Prof., Mölndal SWEDEN
Freddie H. Fu, MD, Pittsburgh, PA UNITED STATES

Kobe University, Kobe, Hyogo, JAPAN

FDA Status Not Applicable

Summary: Pivot shift test was quantitatively evaluated by an accelerometer and video-based iPad system at four centers. Weak but significant correlations were observed between the measurements and clinical pivot shift grade, and the measurements were able to discriminate between high and low grade pivot shift. Quantitative measurement with accelerometer and iPad may be useful to quantify the pivot shift.

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Abstract:

Introduction

The rotational laxity, or the pivot shift test, is a key to understand the anterior cruciate ligament (ACL) function after the ACL injury and reconstruction. Various measurement methods have been developed to quantify the pivot shift test, but the clinical implications of the measurement results has not been established mainly because of a wide variability of the pivot shift test between different examiners. The purpose of this study was to determine the relationship between quantitative measurement and clinical grade of the pivot shift test at four international centers.

Methods

Seventy-three unilateral ACL injured patients at four different sites were included in this study. While performing the standardized pivot shift test, two quantitative technologies were utilized; the accelerometer and the image analysis system using iPad. Accelerometer wireless sensor (KiRA, Orthokey, Italy) was attached on the lateral side of the tibial tubercle using a strap. The tibial acceleration was recorded through a Bluetooth connection to the tablet PC. Image analysis of lateral compartment translation was simultaneously performed using a specially programmed iPad (Apple Inc, USA) application, which tracked the movement of three markers on the lateral side of the knee joint (two on the lateral tibial plateau and one on the lateral femoral epicondyle) to measure the anterior-posterior shift between the lateral tibia and femur. The tibial acceleration and the lateral compartment translation were provided and compared to the clinical pivot shift grade (grade 0, 1, 2 and 3). Spearman correlations were used to determine the relationship between the quantitative measurements and clinical pivot shift grade. Because of the limited number of individuals with a grade 0 and 3 pivot shift test, we used independent t-tests to compare the quantitative measurements between those with a grade 0 or 1 (low grade) pivot shift versus grade 2 or 3 (high grade) pivot shift. The alpha level was set at p<0.05.

Results

There were weak correlations between the quantitative measurements and clinical pivot shift grade (acceleration: 0.32, translation: 0.31, p<0.01). High grade pivot shifts had larger acceleration (4.1±1.8 m/sec2) than low grade (3.1±1.8 m/sec2, p<0.05). The difference in tibial translation between high and low grade pivot shifts approached significance (2.4±1.5 vs. 1.7±1.4 mm, p=0.054).

Discussion

Clinical grading of the pivot shift has long been utilized as an index of the knee function after ACL injury and reconstruction. Weak but significant correlations between the quantitative measurements and clinical grading suggests that the pivot shift measurement by translation and acceleration can be used as a substitute for clinical grading. Multiple level classification of the pivot shift test by the measurement was not verified mainly due to inconsistency of the examiners’ judgment of the grading, but rough categorization of the pivot shift could be possible by using the quantitative measurement systems. Universal usability of those measurements and their comparison between different facilities could be suggested.