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    PCL INJURY/TEAR ASSESSMENT

    Automated anterior/posterior drawer test for ACL/PCL Analysis - GNRB PCL

    The GNRB PCL is Genourob's arthrometer dedicated to the analysis of the posterior cruciate ligament (PCL) and the anterior cruciate ligament. This medical device is currently recognized as the product reference in the orthopaedic field for studying the state and performance of the PCL and the ACL by applying an automated posterior drawer test and an automated anterior drawer test.

    GNRB PCL video - How to assess the posterior cruciate ligament (PCL)

    GNRB PCL - Automated posterior drawer test for PCL assessment

    The following section focuses on the PCL option for posterior cruciate ligament (PCL) Analysis. If you are searching for information on the analysis of the anterior cruciate ligament (ACL), we invite you to go on the page dedicated to the GNRB, the medical device that applies LDA® Method for ACL testing. 

    However, it should be noted that when using the GNRB PCL, analysis of the anterior cruciate ligament (ACL) is still available.

    The PCL option added on the GNRB device also currently provides the best precision available on the market for posterior cruciate ligament (PCL) analysis and it is the only arthrometer able to objectively evaluate knee stability because of the dynamic tests it does. Likewise to the GNRB, user friendliness has also been our priority while designing the PCL option. This ultimately led to several parameters and sensors being installed in order to guide the users while running dynamic tests. Because of these parameters and sensors, precise test reproducibility has also become an attribute of the GNRB PCL.

    The LDA® Method for PCL analysis and ACL analysis is an integral part of the GNRB PCL and it is perhaps what makes the GNRB PCL leader on the market for PCL and ACL. The results provided after running tests are shown under the form of a graph with compliance curves (=opposite of the stiffness curves) accompanied by a table chart. This makes the tests easy to understand and to reproduce.

    Example of a posterior cruciate ligament assessment using the GNRB PCL

    Graph 1

    Graph 1

    Graph 1 shows the results obtained after performing tests on both knees of a same patient with the GNRB PCL. The graph shows the compliance curves (=opposite of stiffness curves) obtained after applying several forces on the tibia of the patient to perform and posterior tibial translation.

    This is called a dynamic analysis because calculation of the displacements of the tibia is done while applying different forces which put the posterior cruciate ligament under stress. Therefore, the bigger the displacement differential, the higher the chances of an Anterior Cruciate Ligament tear.

    So far, this is what other arthrometers (Laximeters) have been doing for the past 40 years and it is against this background that Genourob created the GNRB PCL, the first automated tibial translation arthrometer for dynamic assessment of the PCL.

    Click on the title below to learn more about dynamic assessment of the PCL.

    Innovation: Analysing the slopes of the laximetry curves.

    Graph Results of two patients

    Graph Results of two patients

    The graphs above show the GNRB PCL's precision concerning the functional analysis of the posterior cruciate ligament (PCL) instability. The tests shown above are dynamic. They indeed show different forces applied on the tibia associated with different tibial displacements for objectively evaluating the state of the PCL and knee stability.

    So far, only measuring the differential of laxity (only calculating the displacement differential) without consideration of the slopes of the lines does not allow a comprehensive analysis of the ligament state. Ironically, this is what most arthrometers created nowadays do.

    Only studying the displacement differential (doing a static analysis) for analyzing knee ligaments can sometimes lead to false diagnosis and does not give any objective result on knee stability. Both graphs shown above undeniably prove this by comparing two different patients' results.

    Patient 1: No instability in both knees Patient 2: Instability in left knee
    • Displacement Differential = 1.5 mm
    • Curve slope = Parrallel Curves
    • Displacement Differential = 1.5 mm
    • Curve slope = Divergent Curves

    The tables chart above resumes the analysis done between on Patient 1 and 2: The only difference resides in the fact that the slope of the curves do not behave alike for both patients.

    This example purely states the efficiency of running dynamics tests against static tests on the knee. Considering the slope differential between both compliance (=opposite of stiffness) curves on behalf of the displacement differential between both knees ultimately leads to a much more precise analysis of the state and performance of the PCL of the knee.

    The GNRB PCL is therefore nowadays the best Arthrometer (aka. Laximeter) for evaluating the state of the PCL following PCL injuries. Besides, it is also very useful after PCL surgery as is allows the doctors to follow the behavior of the graft over time. Today's surgical techniques indeed need a lot of time for recovering; therefore GNRB PCL is also very useful during posterior cruciate ligament rehabilitation (PCL Rehab).

    How to run tests on the posterior cruciate ligament (PCL) with the GNRB PCL

    GNRB PCL - Patient Positioning Tutorial

    To run a precise diagnosis on the Posterior Cruciate Ligament (PCL) of a patient using Genourob's GNRB PCL, it is required to follow these steps:

    1) Position the patient on the GNRB PCL.

    2) Run the tests on both legs.

    3) Read the results on the graph and its table chart.

    1) Position the patient of the GNRB PCL


    Patient positioning is the first step to run tests on the posterior cruciate ligament (PCL) of the patient. His leg should be in a 45° flexion for optimal PCL testing. This can easily be done with a LDA® Couch which is an accessory especially designed for our products and patient comfort.

    Once the patient is seated, two separate marks shall be placed with a pencil on the apex of the patella and the anterior tibial tuberosity. The leg of the patient shall then be placed on the GNRB PCL with the mark of the apex of the patella being located in the hole of the knee cup. The objective here is to block the patella against the femur so that when tests are run, the femur/patella stay locked in position while the tibia undergoes posterior translation. Following this, the foot is to be locked to avoid any vertical movements and the PCL option shall be placed over the mark of the anterior tibial tuberosity. Finally, the displacement sensor is placed on the PCL option.

    2) Run the tests


    Once patient positioning is achieved, a patient file is to be created on the computer that is provided with the GNRB PCL and the tests shall begin. As soon as a push force is chosen (134, 150, 200 N...), the user can choose to run the tests:

    The PCL option located on the anterior tibial tuberosity starts applying the force on the tibia leading to a posterior translation. When the chosen force is detected, the PCL option stops moving and goes back to its initial position. This ultimately makes the displacement sensor move downwards/upwards leading to the calculation of the displacement of the tibia compared to the force applied. The data collected is then stored in a table chart with a graph showing the laxity curves (=compliance curves).

    Repeat this on the other knee.

    3) Results:


    When the tests are done, the user will find in the results tab the data collected from these tests. They are under the form of a graph showing the compliance curves (=opposite of the stiffness curves) accompanied by a table chart showing the numerical values.

    GNRB PCL main characteristics for optimal PCL/ACL assessment

    • Device using LDA® Method applying posterior tibial translation and anterior tibial translation (Lachman's Test) for PCL, ACL and knee stability objective assessment
    • Dynamic and none-invasive tests
    • Automatic tibial displacement differential and compliance curves slope differential calculation
    • Registration of the patellar fixation force and patient foot / base of the machine distance for reproducibility
    • Delivery with PC and LDA® Software
    • Thrust force from 1 to 200 N
    • Patient data automatically saved, results exportable as xls. files, pdf. format for great communication
    • Dimensions : 845 x 270 x 400mm / 15kg

    GNRB PCL additionnal options

    • Over time, Genourob created several options that could be added to the GNRB such as the PCL option. Initially, the GNRB was created for ACL objective assessment by applying anterior tibial translation.
    • GNRB Rotab is also available and was created to analyze the ACL with more precision by taking into account the calculation of the medial rotation that occurs when applying anterior tibial translation.
    • The main option available is the GNRB Radio: This option was designed to analyze the ACL associated with X-ray technology. The GNRB Radio is indeed made of materials especially adapted to X-technology.
    • Finally, other remaining accessories available are the LDA®Couch which provides the patient with great comfort and is specially designed for our products, the Biofeedback option that allows controlling of the hamstring muscular activity, the LDA®Trolley for storage of the GNRB and the printer for printing the results.