Foot Landing Mechanics

Foot Landing Mechanics, Part 1 of 2

This dialogue is likely going to open up a storm of controversy and dialogue,  …  good !

In a very recent article in LER (Lower Extremity Review) Katie Bell wrote a nice article about foot “Orthotics and Landing Mechanics”.  Her article, and the research she referenced, suggests foot orthoses can affect frontal and transverse plane motion in proximal joints during landing from a jump. It was postulated from the research that orthotics could therefore help reduce the risk of anterior cruciate ligament injury, particularly in females.

In the May issue of the Journal of Applied Biomechanics, it was determined that gender differences as well as foot orthotics affect frontal plane hip motion during landing after a vertical jump. This is really nothing new or mindblowing. Heck, putting a pebble in someone’s shoe will change their landing and gait mechanics, but it is nice to see more talk in the research. Any observant and educated clinician can see that from a vertical jump, if the client does not have enough gluteal function to slow the internal spin of the limb (the glute is a powerful external rotator and thus also a powerful eccentric controller of internal rotation) that the knee will valgus medially. Furthermore, if the foot is not strong and stable, the downward weight will collapse (to varying degrees) the arch and thus also drag the knee medial. Thus, it is critical to discuss both components of knee stability, meniscal issues and ACL issues.  Any study omitting observations of gluteal function and only commenting on the effect and merits of the orthotic to control the knee is only telling half the story. Admittedly, research articles can look at isolated issues like this study did if it pleases them, but it is our mission not to let tunnel visioned biases enter into things. Tunnel vision leads to assumptions that some problems have simple solutions. Our clients get evaluated through the entire kinetic chain when looking at foot and knee issues. Heck, even arm swing and opposite leg swing impact the function of the stance phase knee (look at the mechanics behind the Abductory Twist for example or read our blog posts from early December on arm swing impacting lower limb mechanics).

We are not dismissing these research findings however, yes orthotics can help reduce risk at the ACL …  IN SOME CLIENTS, but it could enable risk in others if the correction at the foot is not the proper intervention. What if the entire risk scenario is from a dysfunctional hip ? Now you have changed the foot’s dynamic compensation for the hip dysfunction. Couldn’t that increase ACL risk ? You bet it can. Thankfully, as we read on, the LER article quoted Walter Jenkins PT, DHS, associate professor and chair of ECU’s Department of Physical Therapy. “Dysfunctional hip motion is commonly observed in patients with knee pathology.” It was nice to see that, sadly we felt the articles angle was to mediate the dysfunctional hip motion via correction at the bottom. We all should be reminded that the organism must be evaluated and thus treated as a whole.

Modifying dysfunctional hip motion locally, if there are local issues, can reduce knee risk and may modify the necessity or degree of intervention at the foot level. So, landing mechanics are about the foot, the hip and the knee mechanics pending the mechanical forces from those other two joints above and below. Merely adding an orthotic is going to change the landing mechanics but, as we mentioned earlier, putting a pebble in someone’s shoe is going to change their foot dynamics and how they load, so is a pebble a reasonable answer too ? The question is are they the mechanics you want for your client ? Are the foot changes with an orthotic locally prostituting the normal hip mechanics ? Orthotics are not the Holy Grail. In some cases they are the Devil’s pitchfork. It takes a very educated and skilled practitioner to know the difference.

The Journal of Applied Biomechanics researchers analyzed the 3D motion of the lower extremities in 36 study participants (18 women, 18 men) during a vertical jump with and without prefabricated foot orthoses. In the women researchers found significantly less hip adduction with foot orthoses compared with no orthoses (p< .05). The men showed no differences between foot orthoses conditions. So, does this mean that the women need orthotics ? Or does it mean that their Q angle is a participant ? Does the study necessarily mean that the answer to these ladies issues is an orthotic ? Or does it mean that they could need more hip stability and loading skills to dampen internal limb rotation and valgus knee drift ? The article (thankfully) does suggest that the apparent gender-specific proximal reactions to foot orthoses during landing may be related to kinematic landing strategies which is a good observation, but do not think that orthoses are the take away answer from this article.

The study also showed things we have talked about previously, that being that men actually land in knee varus and use hip adduction and knee valgus as a strategy to accelerate during the jump after the deceleration phase of landing. Where as women tend to land more valgus and but seem to be more challenged to control this force.  But for an article to suggest that “A foot orthotic may be a simple solution—and quicker than neuromuscular retraining—to control motion.” is a scary conclusion. They go on to say “Ultimately, orthoses may be an excellent adjunct to a neuromuscular training program.” we agree with in part.

Nothing is more valuable than a limb that can support and control itself with optimal neuromuscular function. If you do not have it, take time away from risky sport challenges until you have achieved it. Do not take a short cut and depend on an external device, unless of course the client has a fixed anatomical compensation or issues (ie. forefoot varus) OR you are using it as a training aid, to TEMPORARILY offer mechanics that the client does not have, working toward helping them to eventually get them. In those cases, a device is often helpful and recommended, but IT IS IMPERATIVE  to retrain neuromuscular protective reflexes and function.

We are going to do a Part 2 on this very important topic this weekend. If you are in a sport where you are jumping and landing you absolutely need to read Part 2. We will be offering up a hopeful epiphany for you on why so many people sprain their ankles. It is a landing mechanics problem…… not discussed anywhere else in the research or on the web….. until now !

We are The Gait Guys …. two guys who always finding themselves standing outside some strange box everybody is talking about.

Have a good Friday everyone !

Shawn and Ivo