Reliability of navigated knee stability examination: a cadaveric evaluation.
BACKGROUND
Clinical examination remains empirical and may be confusing in the setting of rotatory knee instabilities. Computerized navigation systems provide the ability to visualize and quantify coupled knee motions during knee stability examination.


OBJECTIVE
An image-free navigation system can reliably register and collect multiplanar knee kinematics during knee stability examination.


METHODS
Controlled laboratory study.


METHODS
Coupled knee motions were determined by a robotic/UFS testing system and by an image-free navigation system in 6 cadaveric knees that were subjected to (1) isolated varus stress and (2) combined varus and external rotation force at 0 degrees, 30 degrees, and 60 degrees. This protocol was performed in intact knees and after complete sectioning of the posterolateral corner (lateral collateral ligament, popliteus tendon, and popliteofibular ligament). The correlation between data from the surgical navigation system and the robotic positional sensor was assessed using the intraclass correlation coefficient. The 3-dimensional motion paths of the intact and sectioned knees were assessed qualitatively using the navigation display system.


RESULTS
Intraclass correlation coefficients between the robotic sensor and the navigation system for varus and external rotation at 0 degrees, 30 degrees, and 60 degrees were all statistically significant at P < .01. The overall intraclass correlation coefficient for all tests was 0.9976 (P < .0001). Real-time visualization of the coupled motions was possible with the navigation system. Post hoc analysis of the knee motion paths during loading distinguished distinct rotatory patterns.


CONCLUSIONS
Surgical navigation is a precise intraoperative tool to quantify knee stability examination and may help delineate pathologic multiplanar or coupled knee motions, particularly in the setting of complex rotatory instability patterns. Repeatability of load application during clinical stability testing remains problematic.


CONCLUSIONS
Surgical navigation may refine the diagnostic evaluation of knee instability.
Pearle
Andrew D
AD
Hospital for Special Surgery, Sports Medicine and Shoulder Service, 535 East 70th Street, New York, NY 10021, USA. pearlea@hss.edu
Solomon
Daniel J
DJ
Wanich
Tony
T
Moreau-Gaudry
Alexandre
A
Granchi
Carinne C
CC
Wickiewicz
Thomas L
TL
Warren
Russell F
RF
D002102:Cadaver; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis*; D007719:Knee Joint / Q000503:physiopathology*; D012371:Robotics; D025321:Surgery, Computer-Assisted; D014481:United States