Orthotics/Functional Limitus

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Could you Biomechanical Gurus out there let me know what the best orthotic construction is for functional hallux rigidus?
I have two patients at present, one a 2o y/o active young girl with metatarsus primus elevatus and a functional limitus. The other is a young man with early arthritis changes as well as the met. elevatus. Both have tight achilles. Both pronate.
I've tried several types of orthotics over the years, is there a "best" one for this ?
Thanks
Steve

 

Steve;

I'd suggest a 1st ray cutout in the device with a poron or ppt back fill up to the level of the 1st metatrsal.

These patient will have a true FF varus in most cases, only moderately reduceable with reduction of teh supinatus and manipulation of the AJ and foot.

Do AJ manipulation if you can. Also, you may want to utilize a FF valgus post of some sort, or a reverse morton's extension to get pressure to the 1st met in a timely fashion.

Finally, consider a digital pad, similar to a cloughy wedge at the hallux or 1-5. Don't forget to accomodate for LLD on the correct side, which is probably the opposite limb but there is no gauruntee of that.
:drinks
Bruce

PS stop by the Tekscan booth to say hello if you are at the Midwest Pod conference in March!

 

"stop by the Tekscan booth to say hello if you are at the Midwest Pod conference in March"

Thank for the advice, I'll follow up on it.
Re: Midwest.....I never miss it- I LOVE Chicago!
See you there
Steve

 

Dear Dr. williams:
Since the forefoot is true varus, is it sopposed to bring the ground up? Therefore, Morton's extention is supposed to be used. I do'nt understand. In addtion, What's the rationale for using digital pad for drsarbes's case? Please explain. Thank you very much for your valuable time in advance. Btw, this is my first post, hope it does not annoy colleagues.
respectfully,
scott ma

 

Scott;

your question is not annoying at all. It saddens me that some members on this list act as if someone's question is too basic to warrant a reply. It is even worse when someone does answer in such a way as make the questioner seem stupid. That said, time to move on.

A true FF varus can only get to the ground thru RF and MTJ compensation. Since this can prolong pronation, you often have to bring the ground up to the foot in these cases. I suggest the soft 1st ray cutout so that the 1st ray may possible addapt and come closer to the ground over time.

The reverse morton's I suggested can help to add a pronation moment to the Forefoot in late midstance. Most cases of functional hallux limitus have peroneal weakness as a counterpart. In late midstance, helping to pronate the FF helps the peroneals to do their job more easily adn can help to keep the 1st met PF'd as the hallux begins to extend.

The digital pad also can help to pre-load the toes in extension. This can help to keep the 1st met PF'd overcoming the DFion forces acting on it that create FnHL.

I hope this helped. If not, ask more adn I will try to explain further.
Sincerely;
Bruce

 

Steve:

In general, I won't make just one type of orthosis depending on a diagnosis. However, I will consider the patient's diagnosis along with their presenting history, physical exam, biomechanical exam and gait exam to arrive at the optimal foot orthosis design for a patient.

For your 20 year old patient with a functional hallux limitus (FnHL), the general goal of the orthosis will be to see if you can reestablish more normal 1st metatarsophalangeal joint (MPJ) during gait. This can be accomplished in FnHL with an orthosis that exerts a subtalar joint (STJ) supination moment, supports the medial longitudinal arch (MLA) well and decreases the ground reaction force (GRF) plantar to the 1st MPJ. Without knowing her weight and activity level and types of sports she participates in, it would be impossible to give you an exact orthosis prescription. However, with the information provided, making a 4 mm polypropylene orthosis shell with 4 degree/4 degree rearfoot post, balanced 2-4 degrees inverted with 2 mm medial heel skive with minimal medial expansion thickness and a full length topcover with a 3 mm korex extension plantar to the 2nd through 5th metatarsal heads would probably work well for the patient to help encourage more normal 1st MPJ function.

If your second patient with degenerative joint disease (DJD) within the 1st MPJ has pain at the end of dorsiflexion of the 1st MPJ during non-weightbearing exam, then a similar orthosis to the one I described above may work but I would put a Morton's extension in the forefoot extension, instead of a 2-5 forefoot extension. The idea here is that with a 2-5 forefoot extension, the range of dorsiflexion motion at the 1st MPJ will be increased during gait (for FnHL), and with a Morton's extension, the range of dorsiflexion motion at the 1st MPJ will be decreased (to limit 1st MPJ pain) during gait.

Hope this helps. And by the way, Steve, I have been very impressed with your recent surgical answers on this forum. I may be needing your expert surgical opinions in the future on some of my own patients. :drinks

 

Scott:

As Dr. Bruce Williams stated, the purpose of Podiatry Arena is to encourage discussion of clinical and theoretical topics that are of interest to the international podiatric medical community. With this in mind, no question, as long as it is made in good faith, is too stupid or annoying, even when this question comes from a student or newly trained podiatrist.

The measurement of forefoot to rearfoot "deformity" is fraught with error. Whether the measurement error is made during drawing the heel bisection, positioning the subtalar joint within its range of motion at "neutral", how the forefoot is being loaded, and how the measurement device relative to the foot is being visualized by the examiner, I would not get too excited about the exact number of degrees of "forefoot varus", "true forefoot varus" or "forefoot supinatus" a patient has. None of us can agree on this so don't sweat it too much.

Instead of saying that a Morton's extension "brings the ground up to the foot", I prefer to think of the mechanical effects of such in-shoe modifications as to how they may affect the ground reaction force (GRF) and, ultimately, the rotational forces, or moments, acting across the joints of the foot and lower extremity during weightbearing activities.

Hope this helps.

 

Kevin;

Please re-read my post. I never suggested that a reverse Morton's extension would bring the ground up to the foot. I instead suggested the it would increase the FF pronation moment in late midstance, thereby assisting the peroneals to increase the pressure sub 1st metatarsal.

:drinks
Bruce

 

Kevin,

Would you still use a Mortons Extension if the first rays were rigidly plantarflexed?

Ann

 

Bruce:

My use of the words "brings the ground up to the foot" was not in reference to anything you said. It was in reference to Scott's question "Since the forefoot is true varus, is it sopposed to bring the ground up?" This seemed to be what Scott was asking....however, in reading his posting more closely, maybe I misunderstood what exactly he was asking.

 

Ann:

I tend to use a Morton's extension only if the patient has a painful dorsiflexion range at the 1st MPJ, or if the patient has a metatarsus primus elevatus with sub 2nd MPJ symptoms. A first ray that is plantarflexed and has high dorsiflexion stiffness would not need a Morton's extension in any clinical situation that I can think of.

Hope this answers your question.

 

Dear all:
Thank you very much for your prompt reply. I am deeply appreciated for your teaching, which is not available from textbooks. Dr.Williams, May I ask one more question? In FnHl. the lateral metatarsal heads have born so much weight already, if we use reverse morton's extention, would it cause more load on 2-5 metatarsal heads which may trigger pain? In addition, how do we know the first metatarsal head has successfully adapted to bear enough load to establish windlass mechanism? If it does establish windlass mechanism successfully, How long does it take? and if the windlass has been established, Shall we remove reverse morton's extension? Dear Dr.Kirby, you did'nt misunderstand my question. Bring the ground up to compensate varus or valgus forefoot is written in many textbooks. Your explanation is very helpful. It appears that morton's extension is rarely used. Are there any guidelins/indications to justify it's use? Many thanks to all of you again
respectfully scott ma

 

Scott;
In general, increasing the load under the lesser mets will not cause pain unless there was an existing metatarsalgia to start with. In a case like that I accomodate the painful MPJ.

In regards to the 1st mpj: if it starts to bear weight appropriately then usually the pre-existing symptamatology will cease. With in-shoe pressure I see an increase in the sub 1st mpj pressure and there will no longer be a FF delay in the F/T curves. In general, from my experience, the windlass will not continue to function without the use of the properly modified CFO. Patients will retain function for a small amount of time, but not more than a few days or so at the most.

I've never used a morton's extension personally. I try to do everything possible to encourage motion at the mpj when possible. There are times when in might be beneficial, such as an acute turf toe injury, etc.

Good luck Scott.
Sincerely;
Bruce

 

Dear Dr.Williams:
Without the aid of F-scan or other similar devices, how do we know modified CFO has successfully done the job? Are there any observable signs or subjective reports from patient?Thank you very much.
respectfully
scott ma

 

Scott;

as I said before, you need to be aware if the patients symptoms improve after attempting to improve First ray function.

There really are not any observable signs w/o the use of in-shoe pressure. You can try to use sandals w/ the orthosis and digital video, but it is very hard to quantify.

I sometimes will modify orthoses that patients present with from other local docs. They, the patients, are usually having syptoms still and most of the devices do not have a heel lift on the short side, or a 1st ray c/o. I will add these and 90% of teh time the patients will have significant improvement of their symptoms.

It is subjective, but really all you have to work with. As you become a more experienced practitioner, as I'm sure Dr. Kirby will confirm, you become more and more intuitive to what patients say their devices feel like, how they feel they walk adn run in them, and what may be contributing to their symptoms. It takes time.
Good luck!
Bruce

 

Kevin,

So in a foot with both a plantarflexed first ray with high dorsiflexion stiffness AND painful dorsiflexion of the 1st MPJ with dorsal spurring, which way would you go?
Morton's or no Morton's?

Thank you,

Ann

 

Dear Dr. Williams and all:
I am a textbook goer. However, I do appreciate your experience, which is extremely valuable. Please let me know if you feel I am nosey. I am trying to search the truth. The concept of bringing the ground up to compasate the forefoot deformity is written in many books,for example,page257, comtemporary pedorthics, byDr. Stephen Albert. Is the concept not valid any more? Moreover, it appears that first metatasal cut out is universally applied to the orthosis modification.I speculate that 3/4 length orthosis is a standard orthosis unless we need to add forefoot modification such as valgus post, metatarsal pad, cluffy wedge, or kinetic wedge. Thank you very much for your valuable tutoring.
respectfully
scott ma

 

When I see a foot like that, I will let you know. Otherwise, trial and error has worked very well for me and my patients in the past.

 

Ann;

in general, without the patient having experienced a traumatic incident, I don't think you would see a patient wiht the characteritics you describe above.

If the DFion stiffness is very high, then there is really very little reason for the 1st mpj to jam, which should preclude it from dorsal spurring in most instances.
Bruce

 

Thank you for your thoughts.

This is a foot type that Larry Huppin speaks about in his talks on pathology specific orthoses. He speaks of foot types that increase ground reaction force under the first ray and lists a congenital plantarflexed first ray as one of these types. He explains that if the midtarsal joint is limited, as it is in my patient, the GRF will act more at the first ray and attempt to dorsiflex it. Because it can't dorsiflex well, the GRF leads to dorsal spurring. He would not use a Mortons Extension because according to his theory this would further jam the 1st MTPJ. His argument makes sense to me, however, I have always used a Mortons for painful limited 1st MTPJ quite successfully. I don't know that I've seen a patient before like this one, however, whose first rays seem to have a high degree of dorsiflexion stiffness and has limited painful 1st MTP joints. Thus my confusion about whether to use the Mortons...

Have I misunderstood because my patient sounds just like the one he describes?

Thank you all for your thoughts and time,

Ann

 

Ann:

I totally agree with Bruce on this one. You normally won't see someone with a significant restriction in hallux dorsiflexion with high first ray dorsiflexion stiffness except post-traumatically. But, I would have no problem with using a Morton's extension on your patient as you have if this resolves the 1st MPJ symptoms effectively, without any negative gait consequences or other symptoms/pathology developing. You're doing a good job!

 

Ann;

I would agree with Kevin as well. It is worth a try and if it works, great!
Bruce

 

Ann,

I agree with Kevin and Bruce also. :drinks

I would also see if the jamming is functional or structural.
Take a stress lateral x-ray (have the patient stand on his toes as high as he can while taking a lateral). If this shows that the dorsal exostosis is preventing movement and there is a limited range of motion, then you know there is a structural hallux limitis. If you do not see the dorsal exostosis blocking movement or you see an adequate range of motion, then it is functional. I know you can do this clinically, but the patient’s weight is not easily reproducible.
For functional hallux limitis, besides making the orthosis that Kevin and Bruce recommend. One additional recommendation I can give is to palpate the area of the tibial sesmoidal ligament. It should be tender. The reason for this is if the joint is prevented from moving, the force is now of plantar separation, and the plantar ligaments bear the brunt of it. I find that some rubbing distally of this area and the lateral plantar area gives an improvement of the joint range of motion. You can also do Conneely's method of releasing the first MPJ, but I will use this if my technique doesn't give me 10 degrees (as his technique is a little time consuming).

Regards,

Stanley

 

We should step back and look at what we are trying to accomplish with the modifications. Why do we add a Morton's extension under an arthritic 1st MPJ. My theory, at this point, and I'd change it quickly if someone came along with a better theory, is that you create sort of a rocker effect with the Morton's extension. That is, as the heel lifts there will be a few decrees of ankle plantar flexion before the tip of the hallux loads and starts to cause pain. I've seen a number of patients where this is effective initially, but becomes ineffective later. My guess is that the patient starts taking longer strides and loads the hallux up enough to cause pain.

The reverse Morton's extension (lift sub mets 2-5) is intended to decrease load on the 1st met and hallux and from that decrease the load on the plantar fascia. Tensioin in the plantar fascia is a major source of the compression forces at the MPJ which is the most likely source of the pain.

So, you have two competing ways to load/unload the joint. So, we are back to trial and error. Or stiff shoes, or rocker soles or...

Regards,

Eric

 

Scott,
You have to be aware of why there is sometimes a lateral shift with hallux limitus. I believe that it is caused by a pain avoidance induced activiation of the posterior tibial muscle. So, a reverse Morton's extension will decrease the need for the posterior tibial activation.

The first metatarsal head does not have to bear load to establish the windlass. In a functional hallux limitus, it is the windlass, or tension in the fascia, that is preventing the hallux from dorsiflexing. The windlass is "established" by unwinding with arch flattening and plantar flexing the hallux. My definition of established is that the tension in the fascia resists and external dorsiflexion moment applied to the foot. Others might have a different definition of established windlass. I would agree with the other posters, who would shy away from using Morton's extensions because they would tend to increase load in the fascia.

Cheers,

Eric

 

Eric;

I completely disagree with the statement above. This is a timing issue more so than a loading issue. A reverse morton's extension increases the load under the 1st met prior to load under the hallux.

As well, when the hallux extends, an increased load will occur within the plantar fascia that will help to stabilize the medial column during late midstance and toe-off.

I know what you are saying about an increased load in the plantar fascia causing the FnHL and Structural arthritis or jamming of the 1st mpj. I don't disagree with you on that either.

I just think you need to clarify this when you regularly make this statement as it is very confusing. Also, until there is definitive data that states there is less load in the plantar fascia while the hallux is extended, significantly less, than when the hallux is plantarflexed, I will continue to argue this point.:bang:

Bruce

 

Eric;

If the peroneus longus is inhibited positionally and becuase of dorsiflexion of the medial column delaying or stopping the loading of the 1st metatarsal, then the posterior Tibial Tendon will be able to fire unopposed.

The posterior tibialis adn anterior Tibialis will fire to avoid a joint that cannot function effectively, with or without pain, and because the peroneals are inhibited.

A reverse mortons extension will allow plantarflexion of the 1st ray which may load the 1st met before the hallux loads allowing establishment of the windlass, true definition - not yours, and this will activate the peroneus longus and then the anterior tibialis and posterior tibialis will no longer need to keep for foot supinated or lateral to avoid this blocked joint.

Bruce:dizzy:

 

I want to thank all of you for your time and advice, and thank you Kevin for your kind words.
Steve

 

No problem, Steve. As many others, including youself, have found out, I can be a real pain sometimes. Your thoughtful surgical opinions are just what Podiatry Arena needs to balance the overwhelming number of posts on biomechanics on this site. Good to see you on the site giving your expert opinions on surgical procedures with your well-written replies.

Keep up the good work.