Effects of “Foot Orthoses” on Running Mechanics in Patellofemoral Pain Syndrome

I have had a couple of emails about this study, mainly in the context that the study does not support the hypothesis I proposed on the potential role of foot orthotics in patellofemoral pain syndrome. Two randomized controlled trials tell us that foot orthotics do work in patellofemoral pain syndrome, so that is not the issue; the issue is the mechanism of action given that other studies show that the traditional model that the use of foot orthotics is based on is not supported.

Here is the study’s abstract:

Effects of medially wedged foot orthoses on knee and hip joint running mechanics in females with and without patellofemoral pain syndrome.
Boldt AR, Willson JD, Barrios JA, Kernozek TW.
J Appl Biomech. 2013 Feb;29(1):68-77.
We examined the effects of medially wedged foot orthoses on knee and hip joint mechanics during running in females with and without patellofemoral pain syndrome (PFPS). We also tested if these effects depend on standing calcaneal eversion angle. Twenty female runners with and without PFPS participated. Knee and hip joint transverse and frontal plane peak angle, excursion, and peak internal knee and hip abduction moment were calculated while running with and without a 6° full-length medially wedged foot orthoses. Separate 3-factor mixed ANOVAs (group [PFPS, control] x condition [medial wedge, no medial wedge] x standing calcaneal angle [everted, neutral, inverted]) were used to test the effect of medially wedged orthoses on each dependent variable. Knee abduction moment increased 3% (P = .03) and hip adduction excursion decreased 0.6° (P < .01) using medially wedged foot orthoses. No significant group x condition or calcaneal angle x condition effects were observed. The addition of medially wedged foot orthoses to standardized running shoes had minimal effect on knee and hip joint mechanics during running thought to be associated with the etiology or exacerbation of PFPS symptoms. These effects did not appear to depend on injury status or standing calcaneal posture.

The study got a reasonable amount of publicity, including at Runners World. This was actually a well conducted, analyzed and written up study except for one unfortunate totally fatal flaw! The “foot orthotics” used in the study were:

6° EVA medial wedges (65 Shore A hardness, Foot Management, Inc., Pittsville, MD) that extended beyond the metatarsal heads

Even the harshest critic of foot orthotics would have to acknowledge that they are not “foot orthotics”! They used a medial wedge the full length of the shoe. No one does that clinically for patellofemoral pain! Also, being under the first metatarsal head it will possibly inhibit the windlass mechanism¹ from working and potentially pronate the foot more! This totally invalidates the study’s findings and contributes nothing to the knowledge base on foot orthotics and patellofemoral pain syndrome.

If you are going to do a study that involves foot orthotics, should not the foot orthotics be of the design and type that are typically, commonly and widely used in clinical practice? I assume that even those who are harsh critics of foot orthotics would have to agree that if any research is to be done on foot orthotics, then this is the criteria that should be applied to the choice of device in a study. Using a ‘foot orthotic’ that is not typically, commonly and widely used in clinical practice is going to be a waste of the researchers time and add no value to the literature (not to mention wasted grant money and the ethics of doing research that will not contribute anything useful).

What should the conclusion to the above study have been? How about:

The addition of a medial wedge of the type that no one actually uses in clinical practice and potentially interferes with the windlass mechanism to standardized running shoes had minimal effect on knee and hip joint mechanics during running thought to be associated with the etiology or exacerbation of PFPS symptoms.

As always: I go where the evidence takes me until convinced otherwise, and this study convinces me of nothing!

¹I will do an article soon on the windlass mechanism as it does keep coming up. (POSTSCRIPT: done it)

Reference:
Boldt AR, Willson JD, Barrios JA, & Kernozek TW (2013). Effects of medially wedged foot orthoses on knee and hip joint running mechanics in females with and without patellofemoral pain syndrome. Journal of applied biomechanics, 29 (1), 68-77 PMID: 22815282

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