Measurements of tibial rotation during a simulated pivot shift manoeuvre using a gyroscopic sensor.

Abstract

The pivot shift has been correlated with patient-reported outcomes and knee function following ACL injury and reconstruction. Tibial rotation has been recognized as an important component to the pivot shift motion path. However, few methodologies exist to quantify tibial rotation in the clinical setting. The purpose of this study was to validate the use of a wireless gyroscopic sensor to measure axial rotation of the tibia during a manually simulated pivot shift manoeuvre in cadaveric specimens. We hypothesized that integrated gyroscopic measurements of tibial rotation velocity (tibial rotation) would be highly correlated with tibial rotations simultaneously recorded with a rotary potentiometer during a simulated pivot shift motion under intact and ACL-deficient conditions. Gyroscopic measurements of rotational velocity were integrated and calibrated to a known arc of rotation. The gyroscope was mounted on the distal tibia with its axis aligned to the tibial shaft. Ten simulations of a pivot shift motion pathway were performed on nine cadaveric knees under intact and ACL-deficient conditions. Logistic regression was used to compare gyroscopic and potentiometer measurements of tibial rotation for both test conditions. Gyroscopic measurements of maximum external tibial rotation during the simulated pivot shift motion pathway were strongly correlated with potentiometer measurements of external tibial rotation in both the intact and ACL-deficient states (R (2)=0.984). The gyroscope evaluated in this cadaveric study was capable of accurately recording tibial rotation during a simulated pivot shift motion pathway.