PCL INJURY/TEAR 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.

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 (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.

In comparison, other arthrometers (Laximeters)  collect data at a certain force which can be described as a static evaluation. Consequently, it is against this background that Genourob created the GNRB PCL , the first automated tibial translation arthrometer for dynamic assessment of the posterior cruciate ligament and anterior cruciate ligament that collects data while applying various forces on the knee.

The two graphs below show the results obtained on the knees of two different patients having suffered from knee ligament injuries after a GNRB test. The green curves show the test results of the healthy knees whereas the red curves show the results of the pathological knees.

As 134 N became the international reference force for assessing the PCL thanks to the KT1000, the GNRB PCL provides the displacement for this given force. However, we can see that the displacements at this point are the same for both patients. This is problematic, as a false PCL diagnosis would be put forward. Yet, it is exactly here that the GNRB shows innovation & precision as an additional diagnosis may be performed through the analysis of the slope of the curves.

In fact, we can determine that Patient 1 has a stable knee while Patient 2 is unstable. Why?

Because on the graph of patient 1, the PCL compliance curves (=opposite of stiffness curves) are parallel and on the graph of patient 2 the PCL compliance curves (=opposite of stiffness curves) diverge.

Consequently, this shows that patient 1 has two stable knees with a slight side-to-side difference in laxity, which remains the same. However, patient 2 clearly shows signs of an increasing side-to-side difference in laxity correlated with the increase of force applied on the knees, hence the diagnosis of an unstable knee.

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 accurate analysis of the state of the PCL present in the knee.

The GNRB PCL is therefore nowadays the most advanced arthrometer (Laximeter) for evaluating the state of the posterior cruciate ligament following knee injuries. Besides, it is also the only device capable of assessing PCL laxity after surgery without any risk thanks to its controlled tibial translation. 

Doctors are thus able to follow the behaviour of the PCL graft over time, which is the key to guarantee knee stability. Today's surgical techniques indeed require a lot of time of recovering therefore making the GNRB PCL indispensable during anterior cruciate ligament rehabilitation (PCL Rehab).

If you are curious in knowing how a test is performed, click on the title below to see a video of a GNRB PCL test.

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.

• 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 LDA®Trolley for storage of the GNRB and the printer for printing the results.