The posterior cruciate ligament during flexion of the normal knee

Abstract

The posterior cruciate ligament (PCL) was imaged by MRI throughout flexion in neutral tibial rotation in six cadaver knees, which were also dissected, and in 20 unloaded and 13 loaded living (squatting) knees. The appearance of the ligament was the same in all three groups. In extension the ligament is curved concave-forwards. It is straight, fully out-to-length and approaching vertical from 60 degrees to 120 degrees, and curves convex-forwards over the roof of the intercondylar notch in full flexion. Throughout flexion the length of the ligament does not change, but the separations of its attachments do. We conclude that the PCL is not loaded in the unloaded cadaver knee and therefore, since its appearance in all three groups is the same, that it is also unloaded in the living knee during flexion. The posterior fibres may be an exception in hyperextension, probably being loaded either because of posterior femoral lift-off or because of the forward curvature of the PCL. These conclusions relate only to everyday life: none may be drawn with regard to more strenuous activities such as sport or in trauma.

A new model to predict in vivo human knee kinematics under physiological-like muscle activation

“…Furthermore, for flexion angles from 401 to 901, the kinematic model predicted an increase in strain of 1.8% of the AL bundle, which coincides with the maximum strain of 2% reported by Nakagawa et al, 2004. The PM-bundle has been reported to be tense throughout the whole flexion cycle, unfolding its load bearing capacity in higher flexion angles (Amis et al, 2003).…”

“…To characterize the laxity/extension of the cruciate ligaments during knee flexion, the relative change in the distances between the grid points representing the tibial and femoral attachment zones of the cruciate ligaments were calculated (Friederich et al, 1992;Li et al, 2004;Nakagawa et al, 2004) throughout the 301 and 901 positions in each subject.…”

The movement of the normal tibio-femoral joint

“…uller, 1982). Since this review does not cover the ligaments, the mechanism will not be discussed except to say that it has been challenged on the ground that the PCL is not tight throughout movement (Fick, 1911;Strasser, 1917;Nakagawa et al, 2004). ''Rollback'' has also been inferred from the use of a central origin on the femur or tibia when measuring knee flexion; because the tibial IR which accompanies flexion occurs around a medial axis, rotation moves a central femoral origin backwards and this may be misinterpreted as ''roll-back'' (Blankevoort et al, 1988;Rovick et al, 1991).…”

Loading Patterns of the Posterior Cruciate Ligament in the Healthy Knee: A Systematic Review

“…Although the PCL is the strongest ligament of the knee joint [40, 41], some scientists have dismissed it as functionally superfluous [32, 42, 43]. These ideas originated mainly from studies reporting either no or very small forces in the PCL during activities of daily living [32, 37, 44] and partially from those stating that an isolated PCL tear may not interfere with patient movement [45, 46].…”

“…These ideas originated mainly from studies reporting either no or very small forces in the PCL during activities of daily living [32, 37, 44] and partially from those stating that an isolated PCL tear may not interfere with patient movement [45, 46]. On the other hand, a number of studies have reported PCL loads very close to or even higher than the failure limit of the ligament during activities such as passive knee flexion, body weight squats and forward lunge [14, 47–49].…”