Dec 22, 2014

Stiff Ankles Could Pose a Serious Risk When It Comes to ACL Injury Risk.

Howdy Folks, today I wanted to discuss a growing body of literature that highlights a relationship between ankle dorsiflexion and movement patterns (kinematics) that are associated with anterior crucial ligament injuries. One such article that was recently published online by the Journal of Athletic Training was conducted by Dill et al1.

Photo Taken from Dill et al journal article.
What did these authors do exactly? They actively recruited and grouped subjects by their levels of ankle dorsiflexion. Specifically, they wanted a population of subjects with limited (Less than or equal to 5 degrees) ankle dorsiflexion and subjects with normal amounts (> or equal to 15 degrees) of ankle dorsiflexion. A unique aspect of this study was that the authors used a weight-bearing lunge test for assessing ankle dorsiflexion.

 It could be argued that this test is both more functional and easier to assess in the clinic compared to nonweight-bearing ankle dorsiflexion measurements. They also took non-weight bearing ankle dorsiflexion range of motion measurements but the authors hypothesized that this measurement may have caused discrepancies in previous studies because this method isn’t a good representation of the functional movements and tasks that were assessed. The weight-bearing lunge test can be assessed using common smartphone apps like Clinometer or the iPhone’s compass application if an inclinometer is not readily available.

Photo Taken from Dill et al journal article.

What are the functional tasks that they tested? Well they had the subjects perform an overhead squat, a single-legged squat, and a jump-landing task. These tasks have been in previous research and are common in clinical settings as well to assess lower extremity movement patterns that help evaluate risk of ACL injury. These are relatively easy to perform tasks and are representative of common physical activities and functional movements in general.

What did these researchers find? They found NO differences between normal and limited ankles when using the traditional nonweight-bearing ankle dorsiflexion range-of-motion assessment. However, there were significant differences when they looked at the two different groups for both the single-legged squat and the overhead squat using the weight-bearing lunge test. They did NOT find a difference in movement patterns when they looked at the jump landing task. 

Previous research by Fong et al2 found a difference with the jump landing task but the current study utilized an immediate countermovement jump for maximal height but the latter researchers did not. This could have been the reason for the differences in findings because the immediate countermovement jump may not have required a significant amount of ankle dorsiflexion to complete.

The next question that you may be asking yourself is what are the kinematics that are associated with increased loading of the anterior cruciate ligament and which of them were present in the subjects with limited ankle dorsiflexion? Well excessive frontal plane, and transverse plane motion accompanied with an anterior tibial shear force (in the sagittal plane) place the greatest stress on the anterior cruciate ligament. Noncontact injuries to this ligament are associated with a minimally flexed or relatively extended knee position. That being said, the subjects with ankles that had limited ankle dorsiflexion did not flex their knees as much as the subjects with normal ankle dorsiflexion during the single-legged squats and overhead squat. This means their knees were relatively extended and as mentioned earlier that is not ideal when it comes to loading of the anterior cruciate ligament. Additionally, the limited group had less ankle dorsiflexion displacement compared to the normal group as well.

So what should you take conclude from all of this and take back with you into the clinic? Well, for one it should be noted that using a non-weight bearing ankle dorsiflexion assessment may not be sensitive enough. The weight-bearing lunge test was much better at identifying these subjects with altered movement patterns. This test is much more field-expedient, is reliable, and can be assessed without the need of a goniometer. Finally, it is evident that there is a growing body of evidence that limitations in ankle dorsiflexion result in kinematics that are associated with increased loading of the anterior cruciate ligament of the knee. This is just another example of how the entire kinetic-chain is important when screening for or assessing injuries. Do you currently assess ankle dorsiflexion when looking to return patients to physical activity or when preventatively screening for risk of injury?

  1.      Dill KE, Begalle R, Frank B, Zinder S, Padua DA. Altered Knee and Ankle Kinematics During Squatting in Those With Limited Weight-Bearing Lunge Ankle-Dorsiflexion Range of Motion. J Athl Train. [Epub Ahead of Print].
  2.      Fong CM, Blackburn JT, Norcross MF, McGrath M, Padua DA. Ankle-dorsiflexion range of motion and landing biomechanics. J Athl Train. 2011;46(1):5–10.


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