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

Abstract

BackgroundThe posterior cruciate ligament (PCL) is the strongest ligament of the knee, serving as one of the major passive stabilizers of the tibio-femoral joint. However, despite a number of experimental and modelling approaches to understand the kinematics and kinetics of the ligament, the normal loading conditions of the PCL and its functional bundles are still controversially discussed.ObjectivesThis study aimed to generate science-based evidence for understanding the functional loading of the PCL, including the anterolateral and posteromedial bundles, in the healthy knee joint through systematic review and statistical analysis of the literature.Data sourcesMEDLINE, EMBASE and CENTRALEligibility criteria for selecting studiesDatabases were searched for articles containing any numerical strain or force data on the healthy PCL and its functional bundles. Studied activities were as follows: passive flexion, flexion under 100N and 134N posterior tibial load, walking, stair ascent and descent, body-weight squatting and forward lunge.MethodStatistical analysis was performed on the reported load data, which was weighted according to the number of knees tested to extract average strain and force trends of the PCL and identify deviations from the norms.ResultsFrom the 3577 articles retrieved by the initial electronic search, only 66 met all inclusion criteria. The results obtained by aggregating data reported in the eligible studies indicate that the loading patterns of the PCL vary with activity type, knee flexion angle, but importantly also the technique used for assessment. Moreover, different fibres of the PCL exhibit different strain patterns during knee flexion, with higher strain magnitudes reported in the anterolateral bundle. While during passive flexion the posteromedial bundle is either lax or very slightly elongated, it experiences higher strain levels during forward lunge and has a synergetic relationship with the anterolateral bundle. The strain patterns obtained for virtual fibres that connect the origin and insertion of the bundles in a straight line show similar trends to those of the real bundles but with different magnitudes.ConclusionThis review represents what is now the best available understanding of the biomechanics of the PCL, and may help to improve programs for injury prevention, diagnosis methods as well as reconstruction and rehabilitation techniques.

Length-Change Patterns of the Collateral Ligaments During Functional Activities After Total Knee Arthroplasty

“…One important aspect to consider in any investigation into elongation patterns of passive soft tissue structures is that the zero-strain condition of the ligament fibers remains unknown. 19 To deal with this important issue, all ligament elongation data were normalized to the length of the ligament fibers at heel strike of the level gait cycles. As a consequence, the reported ligament elongation patterns can only be subjectively compared to those obtained with a different choice of reference length.…”

Lower Limb Biomechanics During Level Walking After an Isolated Posterior Cruciate Ligament Rupture

“…In passive knee flexion, the strain of the PCL decreases from 0 to 30 and increases from 30 to 90 , with the smallest strain at 30 of knee flexion. 17 The PCL is stressed maximally at full extension during the stance phase of level walking. 41 Increased posterior translation was found in those patients with acute tears of the PCL when the knee was close to extension.…”

“…PCL strain increases from knee flexion 30 to full extension and increases from 30 to 90 of knee flexion. 17 Without the stabilization from the PCL, the posterior GRFs tend to make the knee more unstable. Therefore, the reduced posterior GRFs during the terminal stance phase and the preswing phase may be adaptation strategies to avoid excessive tibial posterior displacement caused by PCL deficiency.…”

Inertial Sensor-Based Lower Limb Joint Kinematics: A Methodological Systematic Review

“…Evaluating kinematical characteristics is crucial for a correct clinical understanding of complex functional movements such as gait [1], a forward lunge and other tasks requiring optimal motor control [2]. Studying kinematics can help in the assessment of the patients' functionality and progression in their rehabilitation period.…”