Simulated Pivot-Shift Testing with Single and Double-Bundle Anterior Cruciate Ligament Reconstructions

Abstract

Reduction or elimination of the pivot-shift sign is an important goal for anterior cruciate ligament reconstruction. In our model, the results show that a single-bundle reconstruction was sufficient to restore intact knee kinematics during a simulated pivot-shift event. The higher graft forces with some double-bundle graft-tensioning protocols reduced the coupled rotations and displacements from an applied valgus moment to less than the intact levels. This overcorrection should theoretically make the knee less likely to pivot but could have unknown clinical consequences.

Anterior cruciate ligament reconstruction creating the femoral tunnel through the anteromedial portal. Surgical technique

“…Advantages in AM portal technique are: a better visualization of the lateral wall of the intercondylar notch; a more anatomic graft placement because the socket is created independently of the tibial tunnel; a more horizontal graft placement leading to a greater knee rotational stability: in interference screw fixation, a parallel socket and screw angle; any fixation type is compatible; in all, inside technique is the only way to create the femoral tunnel; revisions may be easily performed [11][12][13][14][15][16].…”

Basic biomechanic principles of knee instability

“…From the in vitro setting, the use of customdesigned robotic mechanisms ( Fig. 1) and industrial robotic manipulators has enabled researchers to standardize the magnitude and direction of forces and moments applied to the knee [19][20][21][22][23]. This has allowed the practice of repeatable forces applied to the joint under study.…”

Electromagnetic tracking of the pivot-shift

“…Although the instrumented spatial linkage [28][29][30] or robotic system [31,32] can accurately measure the 6 DOF of the knee joint, they are exclusively applicable in cadaveric studies. In vivo evaluation of the 6-DOF knee movements during the pivot-shift test was first performed by Bull et al using the electromagnetic system [33].…”