Correlation between a 2D simple image analysis method and 3D bony motion during the pivot shift test.
BACKGROUND
The pivot shift test is the most specific clinical test to detect anterior cruciate ligament injury. The purpose of this study was to determine the correlation between the 2D simple image analysis method and the 3D bony motion of the knee during the pivot shift test and assess the intra- and inter-examiner agreements.


METHODS
Three orthopedic surgeons performed three trials of the standardized pivot shift test in seven knees. Two devices were used to measure motion of the lateral knee compartment simultaneously: 1) 2D simple image analysis method: translation was determined using a tablet computer with custom motion tracking software that quantified movement of three markers attached to skin over bony landmarks; 2) 3D bony motion: electromagnetic tracking system was used to measure movement of the same bony landmarks.


RESULTS
The 2D simple image analysis method demonstrated a good correlation with the 3D bony motion (Pearson correlation: 0.75, 0.76 and 0.79). The 3D bony translation increased by 2.7 to 3.5 times for every unit increase measured by the 2D simple image analysis method. The mean intra-class correlation coefficients for the three examiners were 0.6 and 0.75, respectively for 3D bony motion and 2D image analyses, while the inter-examiner agreement was 0.65 and 0.73, respectively.


CONCLUSIONS
The 2D simple image analysis method results are related to 3D bony motion of the lateral knee compartment, even with skin artifact present. This technique is a non-invasive and repeatable tool to quantify the motion of the lateral knee compartment during the pivot shift test.
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, Hospital Universitário, Canoas, RS, Brazil. Electronic address: fabioarilla@hotmail.com.
Fabio V
FV
Arilla
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: amir.ata.azar@gmail.com.
Amir Ata
AA
Rahnemai-Azar
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: carlos.yacuzzi@hospitalitaliano.org.ar.
Carlos
C
Yacuzzi
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: guenther.Daniel@mh-hannover.de.
Daniel
D
Guenther
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: bse3@pitt.edu.
Benjamin S
BS
Engel
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: ffu@upmc.edu.
Freddie H
FH
Fu
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: musahlv@upmc.edu.
Volker
V
Musahl
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: genesis1@pitt.edu.
Richard E
RE
Debski
D000070598:Anterior Cruciate Ligament Injuries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008875:Middle Aged; D015588:Observer Variation; D016059:Range of Motion, Articular / Q000502:physiology*
ACL; Kinematics; Knee; Pivot shift test; Reliability