TOP 6 ACL DIAGNOSTIC TESTS

Arthroscopy (also called arthroscopic surgery) can also be used to diagnose the state of the ACL.

This technique being a surgical procedure, it holds the last position in our article, as it is by far the most invasive technique to assess the anterior cruciate ligament.

This examination is performed using an arthroscope that is inserted into the joint through a small incision so that the ACL can be directly seen on a computer screen.

Radiography is also a recognized technique for analyzing the anterior cruciate ligament. The TELOS is a famous device, which was used to run radiography assessment on patients suffering from ACL injuries by analyzing the position of the tibia compared to the femur while applying a single force on the tibia.

The objective results provided by this type of evaluation are interesting but the radiography technology, which is required, makes it very invasive for the patient thus the reason it holds the 4th position.

Manual Arthrometers such as the KT1000/KT2000 are interesting but lack reproducibility and precision when it comes to analysing complete and partial ACL tears.

The way the arthrometer is placed on the leg indeed greatly determines the end result. Motorised arthrometers have indeed corrected this by adding sensors to analyse the ACL.

This type of assessment is probably the first evaluation you will undergo if you suspect an ACL tear. Many different physical examination tests may be done such as the Lachman test, the pivot shift test, the anterior drawer test or the jerk test.

While clinical physical manoeuvre are essential, they often rely on subjective factors such as clinician experience, muscle relaxation, and inherent knee variability. Physical diagnosis is particularly difficult in large patients and in patients with an acute injury and soft-tissue swelling and guarding. Partial ACL tears are also quite difficult to assess during physical examination.

However, this type of assessment still remains necessary to have a first clue on the state of the anterior cruciate ligament.

MRI is a common technique for objectively diagnosing an ACL tear. Second place has been given to this assessment technique because MRI findings are not helpful in ruling in or ruling out knee instability. This is primarily due to the fact that diagnosis is made while the patient remains in a single position making it impossible to see the tibia's behaviour compared to the femur. 

In addition, time is also needed after an ACL injury as the swelling present in the knee makes it difficult to diagnose the state of the ACL. This problematic is the result of the blood surrounding the ACL.

However, it should still be noted that ACL injury management is critically dependent on accurate diagnosis of other surrounding ligamentous structures of the knee, in particular the lateral collateral ligament (LCL), the posterior cruciate ligament (PCL) and the meniscus. These structures can indeed be assessed using MRI scans, which still makes this technique of evaluation highly worthy of application in the management of patients suffering form ACL injuries.

Patients with combined LCL/ACL or PCL/ACL tears indeed show profound instabilities requiring a more technical surgical procedure, which, if not taken into consideration predisposes the ACL graft to higher chances of collapsing.

Finally, we placed arthrometers at N°1 as they apply the less invasive and yet most reliable technique to assess the ACL. The GNRB & DYNEELAX are an example of arthrometers used nowadays for ACL diagnosis & treatement.

In case you didn't know, your ACL is like an elastic which your body initially generates to stabilize your knee. Now, since we compared it to an elastic, imagine you had one in front of you and you wanted to determine whether it is torn or not:

• would you pull on it using your hands?
• or would you use a camera to take pictures and get them analyzed to determine a tear?

Anyone would of course pull on it, and this is exactly what arthrometers do. It applies a translation force or a torque on the tibia to calculate the resulting displacement or rotation while maintaining the femur bone locked in position. The tests are first done on the healthy knee and then on the pathological knee in order to compare both differentials, which lead to a precise and objective assessment of the anterior cruciate ligament and other ligamentous structures.

We placed arthrometers / laximeters N°1 at determining ACL tears because the assessments performed by these devices are automatically done while applying different forces or torques in a controlled manner. This indeed leads to the analysis of force/displacement or torque/displacement curves (compliance curves), which is the only technique available today for objectively evaluating knee stability without being invasive.

In addition, these features make these devices usable after ACL reconstruction surgery, which is essential as personalized rehabilitation programs can be delivered to each patient. With every patient being unique, this is a major characteristic letting arthrometers well deserve their N°1 position on this top 5 of best ways to analyze the ACL.