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Just been thinking,the use of a runners wedge or extrinsic forefoot varus post to sulcus generally is used when pronation occurs into the propulsive phase of gait.However this may just dorsiflex the ist ray causing jamming/limitation of movement at the 1st mpj. Does any one think that the use of a 1st ray cut-out and reverse mortons extension may infact cause the stj to resupinate just prior to propulsion and therefore facilitate a better r.o.m at the 1st mpj and improve toe-off?

Any feedback??

scott

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Scott:

I call this "extrinsic forefoot varus post to sulcus" a "varus forefoot extension", not a "post". A "post" generally refers to a plantar addition to the orthosis plate, not a plantar addition distal to the orthosis plate.

I will only use a varus forefoot extension in runners or runnning athletes to increase the subtalar joint (STJ) supination moment on the foot in when they have symptoms related to excess STJ pronation moments (e.g. medial tibial stress syndrome, patello-femoral syndrome). I rarely use them in walking patients, even though about once a year I see a patient with posterior tibial dysfunction that responds well to a varus forefoot extension on their orthosis.

For the past twenty years I have noted that some patients do indeed show increased STJ supination motion and increased stance phase propulsion duration with the use of either a 2-5 forefoot extension or a 4-5 forefoot extension on their orthoses. I have written about this previously and feel that the increase in STJ supination with a 2-5 or 4-5 extension is due to increased lateral stability allowing the patient to better use their gastrocnemius-soleus complex to supinate their foot in late midstance and propulsion (Kirby, Kevin A.: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997). This type of forefoot extension may also be used in the medial heel skived orthoses of patients with posterior tibial dysfunction to increase propulsive phase function and to decrease symptoms.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
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Voice: (916) 925-8111 Fax: (916) 925-8136
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In my meagre experience I find these to work v well esp in say medial tibial stress syndrome with a pt who has a high degree of rearfoot/tibial/running varus. Not so good for ff supinatus/equinus type overpronated runners.

I feel that running is different to walking due to running limb varus and not so much "high gear" as "low gear". I dont feel that 1st c/o's and 2-5 pads are so useful because of this and varus ext's more appropriate in runners but it does make the orthotic exclusively for running. Lots of happy long distance runners out there who happen to have v little 1st MTP motion!

I dont use much - perhaps 3 degrees and if you are at all concerned thin it under the 1st met head and fill with poron.

I am a Podiatric Biomechanical Engineer and Researcher at the Primary Research Facility in Rome Italy (Department of Biomedical Engineering). My area of interest for the past 20 years has been the impact faulty foot mechanics has on postural mechanics and related chronic musculoskeletal pain syndrome.

Initially we started evaluating Rootian Biomechanics, then shifted into forefoot mechanics, and for the last 10 years, conducting research on Proprioceptive Insoles.

I invite you to visit my website at: http://www.rothbartsfoot.bravehost.com

I believe you will find the information of significant interest. The site contains not only my research, but references to research across Europe on Proprioceptive Stimulation.

Your comments or opinions are most welcome.


Prof / Dr Brian A Rothbart
Department Biomedical Engineering
Rome, Italy

I agree with Kevin's definition of extension rather than post. However, I don't think that there is an authoritative source on definitions of orthotic parts. :) I use varus extensions in patients who have lateral column symptoms and also patients who have limited eversion available. When a patient is asked to evert their foot and they cannot lift their lateral forefoot off of the ground due to lack of range of motion there is a high liklihood of overloading the lateral column. This is the Rootian idea of the partially compensated varus. It doesn't matter if it is forefoot or rearfoot varus, both will contribute to lateral column overload. The varus extension shifts the load to medial forefoot.

This is different than putting a varus extension who has a lot of eversion available. There may be less eversion, but the point of the original post is well taken. There may be jamming (increased load) of the first ray with the extension. If you see less pronation you have to ask what anatomical structure is stopping pronation at this new position. Is it the same ones or has the sinus tarsi been removed as one of the structures stopping pronation thus increasing the stress on the other structures?

just curious if anyone could post a conceptual pic of a varus forefoot extension?

Scott,

do it all the time, Intrinsic ff valgus post, reverse mortons ext and first ray cut away. Allows transfer of weight from heel to toes and through high gear push off without restricting first MTPJ ROM

Adding anything directly under the first MTPJ with reduce ROM, create a lateral shift in COM and result in an abductory twist/.pronation in to propulsion.

__________________
Graham Curryer

None of us know what we are doing, but some of us know more about what we are not doing than others!::