3D kinematic in-vitro comparison of posterolateral corner reconstruction techniques in a combined injury model

Abstract

With the variable injury pattern to the posterolateral structures (PLS) of the knee, a number of reconstructive procedures have been introduced. It was the aim of the present study to evaluate the resulting 3D kinematics following three different surgical techniques of reconstruction in a combined posterior cruciate ligament (PCL)/PLS injury model. In nine human cadaveric knees, 3D kinematics were recorded during the path of flexion-extension using a computer based custom made 6-degree-of-freedom (DOF) testing apparatus. Additional laxity tests were conducted at 30 and 90 degrees of flexion. Testing was performed before and after cutting the PLS and PCL, followed by PCL reconstruction alone. Reconstructing the posterolateral corner, three surgical techniques were compared: (a) the posterolateral corner sling procedure (PLCS), (b) the biceps tenodesis (BT), and (c) a bone patellar-tendon bone (BTB) allograft reconstruction. Posterior as well as rotational laxity were significantly increased after PCL/PLS transection at 30 and 90 degrees of flexion. Isolated PCL reconstruction resulted in a remaining external rotational deficiency for both tested flexion angles. Additional PLS reconstruction closely restored external rotation as well as posterior translation to intact values by all tested procedures. Compared to the intact knee, dynamic testing revealed a significant internal tibial rotation for (b) BT (mean=3.9 degrees, p=0.043) and for (c) BTB allograft (mean=4.3 degrees, p=0.012). (a) The PLCS demonstrated a tendency to internal tibial rotation between 0 and 60 degrees of flexion (mean=2.2 degrees, p=0.079). Varus/valgus rotation as well as anterior/posterior translation did not show significant differences for any of the tested techniques. The present study shows that despite satisfying results in static laxity testing, pathological 3D knee kinematics were not restored to normal, demonstrated by a nonphysiological internal tibial rotation during the path of flexion-extension.