ACL TEST - ADAPTED TO X-RAY TECHNOLOGY

Presently, it is the device that provides the best precision and it is the only arthrometer able to objectively evaluate knee stability because of the dynamic tests it does. User friendliness has also been taken into account while designing this arthrometer leading to several parameters and sensors being installed in order guide the users while running dynamic tests. Because of these parameters and sensors, precise test reproducibility has also become an attribute of the GNRB Radio.

The LDA® Method is an integral part of the GNRB Radio and it is perhaps what makes the GNRB Radio leader on the market for anterior cruciate ligament (ACL) analysis. 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 Radio. The graph shows the compliance curves (=opposite of stiffness curves) obtained after applying several forces on the tibia of the patient (anterior 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 anterior cruciate ligament under stress. Therefore, the bigger the displacement differential, the higher the chances of an ACL 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, the first automated tibial translation arthrometer for dynamic assessment of the anterior cruciate ligament that collects data while  applying various forces on the knee.

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

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 ACL thanks to the KT1000, the GNRB Radio 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 ACL 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 ACL compliance curves (=opposite of stiffness curves) are parallel and on the graph of patient 2 the ACL 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 ACL present in the knee.

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

Doctors are thus able to follow the behaviour of the ACL 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 indispensable during anterior cruciate ligament rehabilitation (ACL Rehab).

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

To run a precise diagnosis on the ACL of a patient using Genourob's GNRB Radio, it is required to follow these steps:

1) Position the patient on the GNRB Radio.

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. Initially, this arthrometer was created for ACL objective assessment by applying anterior tibial translation.

• GNRB PCL is also available and was created to analyze the PCL by applying posterior tibial translation.

• The last option is the Rotab Option 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.

• 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.