Clinical grading of the pivot shift test correlates best with tibial acceleration.
OBJECTIVE
Recently, different measurement systems have been developed to quantitatively measure the pivot shift in vivo. These systems lack validation and a large inter-examiner variability for the manually performed pivot shift test exists. The purpose of this study was to perform objective measurements of the pivot shift using three different measurement devices and to examine the correlation of the measurements with clinical grading of the pivot shift.


METHODS
A cadaver knee on a whole lower body specimen was prepared to display a high-grade pivot shift. The pivot shift tests were performed three times by 12 blinded expert surgeons using their preferred technique. Simultaneous data samplings were recorded using three different measurement devices: (1) electromagnetic tracking system using bone-attached and skin-fixed sensors, respectively, (2) triaxial accelerometer system, and (3) simple image analysis. The surgeons graded the knee clinically using pivot shift grades I-III. Correlations were calculated using the Spearman's rank correlation coefficient.


RESULTS
The expert surgeons average clinical grading was 2.3 (SD ± 0.5). Clinical grading displayed best correlation with the acceleration of reduction as measured by electromagnetic tracking system with bone-attached sensors (r = 0.67, P < 0.05). Similar correlation coefficient was found for the acceleration of reduction (r = 0.58, P = 0.05) and the "jerk" component of acceleration (r = 0.61, P < 0.05) measured by means of the triaxial accelerometer system.


CONCLUSIONS
The pivot shift can be quantified by several in vivo measurement devices. Best correlation with clinical grading was found with tibial acceleration parameters. Future studies will have to analyze how quantitative parameters can be utilized to standardize clinical grading of the pivot shift.


METHODS
Diagnostic study, Level II.
Department of Orthopaedics, Sahlgrenska University Hospital/Mölndal, 431 80 Mölndal, Sweden. mattias.e.ahlden@vgregion.se
Mattias
M
Ahldén
Paulo
P
Araujo
Yuichi
Y
Hoshino
Kristian
K
Samuelsson
Kellie K
KK
Middleton
Kouki
K
Nagamune
Jón
J
Karlsson
Volker
V
Musahl
D000054:Acceleration; D000368:Aged; D053587:Arthrometry, Articular / Q000379:methods*; D001696:Biomechanical Phenomena; D002102:Cadaver; D055590:Electromagnetic Phenomena; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D015588:Observer Variation; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D013977:Tibia / Q000502:physiology*