A non-invasive device to objectively measure tibial rotation: verification of the device

Abstract

The purpose of this study was the correlation of the results of a new measurement device for tibial rotation (Rotameter) in comparison with the measurements of a knee navigation system as standard method. In a biomechanical laboratory study, all soft tissues were removed from 20 human cadaveric knees leaving only the intact capsule and the bone. Specific tracers were bicortically fixed in the bone in order to measure tibial rotation using a knee navigation system. The knees were fixed to a custom-made inside-boot to rule out undesirable rotation of the reconstruction inside the Rotameter measurement device. Internal and external rotation values were measured at an applied torque of 5, 10 and 15 Nm. The different methods to evaluate tibial rotation were compared using the Pearson correlation coefficient. The correlations were deemed to be reliable if a value of >or=0.80 was achieved. At 5 Nm of applied torque, high correlations for the internal rotation, external rotation and the entire rotational range were found in the Pearson correlation coefficient between the Rotameter testing device in comparison with the knee navigation system as invasive reference method. These results were also confirmed at an applied torque of 10 and 15 Nm. In conclusion, the Rotameter testing device showed high correlations compared with the knee navigation system as an invasive standard method. It might be used as a non-invasive and easy alternative to investigate tibial rotation.

Objective measurements of static anterior and rotational knee laxity

“…Hips are extended and knees flexed at 30°. The Rotameter overestimates the total range of rotation at 5, 10, and 15 Nm by an average of 5, 10, and 25°, respectively [33]. ICCs for these different torques were superior to 0.67 [34].…”

“…No data is available on its reproducibility. -Rotameter [33]: Two prototypes of the Rotameter exist. In both versions, the subject is lying prone to reproduce the dial test position.…”

Static rotational knee laxity in anterior cruciate ligament injuries

“…Six different measurement devices were identified in the recent literature to assess static rotational knee laxity [2,4,23,29,32,38]. The most important finding of the present review was that testing procedures and in vivo measurement conditions were highly variable, yielding results with up to threefold differences.…”

“…Table 1) [4,23,32,38]. The other two allowed for measurements at different knee flexion angles [2,29].…”

In vitro analysis of varus-valgus laxity of the knee joint: Comparison of clinical evaluation with measurements using a reference motion analysis system

“…Other devices are dedicated to rotational measurements, like electronic goniometers [13] or gyroscopes and accelerometers [14,15]. Opto-electronic or magnetic 3D positioning techniques can assess both rotations and translations [16][17][18]. The measurement accuracy and reliability of these instruments have been widely studied [12,14,[16][17][18][19][20][21][22].…”