Symptomatic Juvenile HAV in identical twins; case report.

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Hi All

I had the pleasure of seeing a referral for 9 year old identical twins today with juvenile HAV who are recently developing joint pain. They are extremely confident “bright” kids.

Prior consultation to date was from pediatrician who prescribed over the counter arch supports approximately 5 years ago and pediatric orthopedic surgeon who doesn’t want to intervene currently (good).

I think this represents an opportunity for useful case study and I wanted to see if there was any enthusiasm for those with experience with his problem to aid me with workup and treatment plan.

I discussed with mother and kids possible benefits to them of having some excellent experience and knowledge from podiatrist forum guiding me and for the podiatry community having identical twins to “ponder” albeit from a distance. This is relatively uncommon and possibly unique opportunity. They all seemed very excited at possibility and the attention this might foster, and agreed verbally to allow communication of their cases on the forum if I am meticulous about keeping the information anonymous. I see no ethical arguments against doing this though obviously it warrants thought.

Health wise there are no relevant problems although interestingly both have hearing deficit, uni-latateraly one twin left other right, one needs hearing aid the other not. One has congenital aortic valve stenosis which is resolving to a valve murmur and is currently being monitored without having any apparent health concerns or causing restrictions in activity.

My exam today show essentially identical features, they have level of activity participating in same sports, are in same school class, and mostly hang out together.

Chief complaint is intermittent mild medio-dorsal 1st metatarso-phalangeal joint pain only with increased activity of gym and sports. Pain is also worsened wearing certain foot-wear particularly soccer shoes and ice skates. I have not had opportunity to examine foot-wear yet and obviously this needs addressing.
They both have advanced bilateral HAV, no skin lesions or evidence of injurious foot-wear related superficial soft tissue stress. There is decreased range of motion at 1st metatarso-phalangeal joints, forefoot valgus, estimated at approx 45 degree dorsiflexion in open chain exam. Provocative testing; mild discomfort at dorsal 1st metatarso-phalangeal joint with barefoot single limb stance heel raises X 10. I have impression of medially deviated sub-talar joint axis – difficulty inverting foot applying manual pressure to medial plantar heel when dependent. Evidence of functional hallux limitus with attempted weight bearing dorsiflexion of first metatarso-phalangeal joint. Range of motion of metatarso-phalangeal joint increases with plantar flexion of 1st ray and joint locks with dorsiflexion of 1st ray.
Watching patient walk I see; abductory twist at HO, and foot aligned parallel to LOP during gait.

I have scheduled them for a 3 hr static and dynamic workup next week, the fee for this visit will be the cost of a normal MSK exam which is covered by insurance and is a prerequisite for prescribed foot orthoses.

Although I would not normally go to such length to collect kinematic and kinetic data this is an unusual opportunity which I think they may benefit from by getting optimal opinion, I may benefit from by learning stuff from you guys and the podiatry arena community may benefit from by virtue of its vigor and divergent opinion.

My initial thoughts are;

Is intervention warranted if so what and why?

In terms of examination what is regarded as optimal, what might be limitations of exam?

Being identical twins I am curious to see how subjective and objective examination compare, as might be expected, essentially the same, (or not) will systemic and operator error distract from this?

Exam I propose to do will include following:

FPI

supination resistance testing ( I have developed prototype based on CP’s research model)

Lunge value(for weight-bearing ankle flexibility measurement) - ( I have developed prototype also based on CP’s research model).

In shoe and barefoot pressure measurement with particular interest in forefoot loading force/time curve velocity as per Norm Murphy’s 3 box idea.

Synchronized saggital and frontal video exam of kinematics at 120 fps.

Plus anything else anyone might reasonably request which I am able to provide.


Cheers


Martin



The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Mart,

Quick reply as I don't have much time now.
Night splints + well designed functional foot orthoses.

Yes, measurement error will be important, but basically differences in these "clones" is down to environment + measurement error. Understand though that their shared environment may also add to their likeness. The ideal study is MZ twins separated at birth. But you'll be able to get estimates of heritability from them for the quantitative variables you measure.

 

Martin:

Sorry I didn't reply sooner to your private posting.

Is your intention to treat one child one way and the other child another way to see the effects on their bunion deformity? This wasn't clear from your posting.

The best way to reduce the pathological forces that contribute to developing HAV and bunion deformity is the following:

1. Increase external subtalar joint supination moments.
2. Decrease external medial forefoot/1st ray plantarflexion moments.

By judiciously using a well-designed custom foot orthosis to alter the distribution of ground reaction forces plantar to the foot, then both of the above changes in rotational forces will likely occur. This foot orthosis will decrease the ground reaction force plantar to the first metatarsal head and hallux and, thereby, will decrease the interosseous compression forces [yes, the foot does have compression forces between the bones and is therefore not a true tensegrity system] at the 1st metatarsophalangeal joint which lead to their joint pain.

If I was the parent of these twins, I would want both of my children treated the same way. However, certainly this set of twins may allow you to do a longitudinal study that you could write up as a nice journal article 10 years from now. I would want weightbearing radiographs of the children's feet on a yearly basis also for 10 years also. Martin, this could become a classic study on the evolution of bunion deformity within the medical literature some day. Are you up to it??

 

Thanks Simon

Night splints would not have been high on my list of Tx options, any useful lit for me to look at off the top of your head?

.

Good point but if Tx plan does turn out different for them, this will likewise reduce the effects of possible environmental differences.

cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

British Journal of Podiatry November 2004 ; 7 (4): 101-105
Conservative treatment of juvenile hallux
valgus - A seven-year prospective study
Andrew J H Macfarlane, T E Kilmartin

Conclusion:
This study has demonstrated that night splints can, over an average of 3
years treatment, prevent the deterioration of juvenile hallux valgus and
subsequent development of associated deformities of the other digits. There
is clear justification for deferral of surgical reconstruction until
skeletal maturity when the outcomes of surgery are likely to be more
predictable. Further, night splint therapy should be considered as a first
line treatment for hallux valgus.

.

You may have difficulty convincing the parents to accept differing treatments for them. If you did then you are obviously manipulating the environmental influences and may see a reduction in the heritability estimates with time, i.e. a increase in environmental variance. You should read about heritability analyses.

 

Thanks Simon

I will not be able to get access to this paper here. Anyone know if this study recoomends this irrespective of amount of presenting deformity? If it did not consider this, any views regarding outcome according to pre-exisiting level of deformation, intuitively this would seem relevent although perhaps unstudied?

this will only happen if there is good reason, currently I do not know how diverse the current critical apprasal of their condition will pan out, that is large part of the exercise right now.

Yep . . . . . . I am out of my depth of knowlege in this area, if Tx plans do diverge I will need to understand this

cheers


Martin


The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Hate to be the teacher handing out the homework, but you are going to need to understand this whether treatment plans diverge or are identical if you are going to start studying twins. About 50% of my PhD was on this topic, so I'll try to help when you get stuck. It's pretty basic math.

 

Shame, give one of them night splints and not the other; one soft devces and the other hard etc. the possibilities are endless...

 

I have no illusions about the limitations of what can be done here, not just with my knowledge and time but also the ethical. If there does seem more of an opportunity here than simply an exercise in optimising my clinical judgement then ethical committee approval would take a year I would estimate so we are looking at first at non invasive measures for sure which would likely exclude serial X ray unless symptoms progress to a point of considering surgery.

On the question of non invasive measures it occured to me that measuring the modulus of hallux adduction might be useful as an index of change which might be expected of the effects of a night splint.

Is there any lit that anyone is aware of that considers what effect a night splint may have and how this might be recorded?

It occured to me to stabilise the semi weight bearing foot on the tibial margins of the 1st metatarso-phalangeal joint and apply a metatarso-phalangeal joint straightenning tensile force on fibial side of prox phallanx and capture the stress/strain data to a certain limit of force. I would estimate that this could be used as an index of effects of splinting on reducing deforming stress. Although this only looks at one component of transverse plane mechanics I think it may have some merit, any views on this idea?

nice to get some ideas flowing already


cheers


Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Martin:

The next time you see the twins, please take a clinical photograph of both of their feet standing, with the camera angle shooting an "A-P view" so that we can appreciate their bunion deformity. It would be nice to see how symmetrical their bunions are from one twin to the other.

I like your idea of testing the transverse plane stiffness of the bunion deformity. I also came up with this idea a few years ago but have never tried it. Do we think that much alike?!

 

Please also measure the HA angle using a finger goniometer. You could also measure ROM in the medial column using the Kilmartin Sagittal Raynger device. It should also be interesting to assess the transverse plane STJ axial position. In short, the more quantitative data you can measure in the time available, the better.

If you have access to a pressure plate, this would make an excellent case report- I don't know of this kind of study being reported in twins before. Get to work Mart.

 

Using the same intervention might still be interesting just to see if they respond in the same way, providing that's warranted (i.e. the conditions are similar enough to warrant similar/same rx) . Interesting case! Thankyou for sharing!

 

I think this may be a sign of me having studied too many of your papers over the years, but at risk of being labeled a “brown noser” I regard that as being “good influence” as my granny might have put it.

Thinking more about trying to measure the abductory stress/strain properties here’s a couple of considerations I have had.

To reduce pressure deforming effects on soft tissue where the adductory force would be applied by using a very inelastic loop of nylon with width of distal phalanx to maximize surface area and reduce soft tissue compression.

Apply force using a motorized test stand / digital force gauge attached to the loop with steel aircraft cable a via a pulley. If I have time tomorrow I’ll try and rig up a prototype and see if I can get some reproducible measurements from a couple of friends (its OK they are used to this kind of thing and just think that I am a bit eccentric) and post a photo.

I was trying to figure out how important rate of loading might be. Given likely visco-elastic properties of the combined resistive joint structures and also the likely small safe excursion to be measured it may be important to control for loading rate. It would be much safer to do apply force manually but this would make loading rate very slow compared to using the stepper motor. Any one has any thoughts on this issue? Perhaps I need to collect data at different rates and see if curves alter significantly to find out.

As far as other aspects of methodology; I thought to take play out of system before starting measurement by loading joint to initiation of motion.

Try and find a constant for deforming contribution of soft tissues under loop. This could be done simply by measuring compliance across distal phalanx within range of force applied. Is this important? I would anticipate it will effect shape of curve but since this will be constant within applied range of force does this matter?

As far as measuring joint angles; rather than use photos (problems with lens distortion and parallax) to take a planar scan using a document scanner and scale it 1:1. That way the measurement is documented with less user error and could be re-evaluated later. Anyone tried this and compared to X ray. Also anyone know . . . how do studies deal with possible variance of position in XRay studies?

I use Amfit system for foot orthosis design and milling and may be able to hack into database to extract Cartesian data points for plantar surface. This would be useful to see weight-bearing effect on plantar contour.

Also I have a Laser scanner but have not had time yet to use quantitatively. Simon I understand you also use a next engine. Any chance of collaborating with 3D modeling software to get some accurate 3D data if you think it may be worth the effort? The problem with using laser is getting weight-bearing data and I have not looked at beam refraction artifact which I anticipate using the nextengine through a glass plate.

Well that’s it for today. All input welcome, I have to establish some kind of methodology during next week.

Cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com

 

Raynger I do not have access to, if anyone has one kicking around gathering dust I would glad pay shipping for loan for a while, or anyone any other ideas for medial column ROM. I am unsure how the Raynger works, could we make some assumptions by accurately measuring Talo/Nav drop from Amfit data if I can Hack it?

Any suggestions to quasi-quantify trans SJJ axial position? I could take some syncronised 2 position video of STJ motion but not sure how best to use this other than qualitatively. Which views would be optimal, anyone tried this?

Also limiting factor is that these guys are 9 years old and will have limited reasonable levels of attentiveness (me too) so may need to ration data collection to that with most likely value, and rank this starting exam at top of list. Also family has to travel considerable distance (we are takling several hours drive) to come and see me so I cannot reasonably follow them too frequently.


cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

No problem with that . . .. . . .. but understand that at the age of 53 I only do homework which is fun and this sounds pretty dry

cheers

Martin


The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com

 

Martin:

Glad to see someone on this site is older than I am (51 y/o).:drinks

Here is how I had invisioned the Hallux Adduction Apparatus (HAA) that I thought of a few years ago. The goal of the apparatus would be to measure the force or moment required to internally rotate (i.e. adduct) the hallux a given number of degrees or distance away from the second digit. In other words, a load-deformation curve would be produced from the data obtained by the HAA which would represent the force and stiffness required to adduct the hallux a certain number of degrees of motion or distance away from the second digit.

The HAA would be constructed with a inelastic loop of nylon webbing attached to a digital tension measuring device with the loop centered on the hallux interphalangeal joint so that when the patient stood on the foot, the force required to move the hallux a certain number of degrees/distance could be recorded. Hallux transverse plane motion could be measured by placing pen marks on the dorsal proximal phalanx of the hallux and measuring the motion of the proximal phalanx under increasing load.

More flexible or, what clinically is called "reducible", hallux abducto valgus (HAV) deformities would have low hallux adduction stiffness, requiring less force to move a farther distance away from the 2nd digit. More "rigid" HAV deformities would have high hallux adduction stiffness, requiring more force to move a shorter distance away from the 2nd digit.

I am attaching an illustration of the HAA that I drew this morning which you or anyone else can use to construct a working model.

 

Played with this idea some years ago. We found that you need to "block" the medial border of the foot just proximal to the 1st MTPJ and also the lateral border to prevent erroneous movement and to isolate the MTPJ, we also set up a pulley to draw the hallux parallel to the supporting surface. Thinking a little more, you'll need to standardize the angle of the tensiometer relative to the hallux abduction angle- didn't do this back then-oops. The question I would ask is: why is this clinically important? I did it because I could.

 

Kevin and Simon

Thanks for artwork Kevin, saved me embarrassment of posting my version which looked like a sausage fishing lure dangling from a badly mutilated condom, into the bin with that!

I am just crimping some aircraft cable to a nylon sling as I take a break for coffee, hope to post a photo of functional rig later today. :morning:

The question I was about to post was regards controlling for tension applied by night splint. This has to be an important variable in fathoming the outcome of using the splint. I am not familiar with the various splint use protocols, ie how is the degree of tension applied, maintained and adjusted? Interesting comparison perhaps with what I would imagine the orthodontists are doing with tooth position and bracing. Anyone have any familiarity with this issue?

The value in measuring the adduction force/strain data is about perhaps predicting the value of a splint, and measuring any changes which might be attributed to its use other than position.

I would estimate that applying a brace to a non reducible deformity might be poorly tolerated, but then tolerance would be a function of force applied. I would think that a mal positioned tooth is a non reducible deformity.

I am not sure what the force/strain plot is going to look like but imagine that there will be a linear section throughout most of the motion which will shift at the boundary of bony impingement. Depending on the starting point of the plot, I would estimate that a characteristic plot will “fingerprint” a particular joint at a given measurement time, it will be interesting to see if this is true and if with twins, the fingerprints have any similarity.

In spite of these fingerprints encompassing the effects of a number of variables this may have value in assessing symmetry within subject or likeness between subjects. It may also give us some basis to recommend some therapeutic guideline in how to apply the brace or even in terms of developing a useful design which can be sophisticated enough to deal with this.

Coffee drained back to crimping and getting the pulley positioned properly.



Cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com

 

Simon:

I was wondering if you had done something like this or not, considering your doctoral thesis was on HAV. Maybe you can draw on my diagram to show, in your experience, where the forces needed to be applied to allow good 1st MPJ motion to be measured. Then possibly you can post the modified drawing back on this thread. Thanks for that.:drinks

What we are measuring with the HAA is the internal first MPJ abduction moment. In other words, we are measuring the internal resistance of the 1st MPJ to hallux adduction motion. We know clinically already that some patients have a fairly compliant hallux that is easy to adduct and some are more stiff being harder to adduct. Since it is the hallux abduction moment at the 1st MPJ that makes HAV deformity occur, then quantitatively measuring it is critical to determine what actually causes HAV deformity.

The results from the HAA could be used with other known measures of assessing HAV deformity to better plan surgical correction and assess surgical results for HAV surgery. It may also be used to better assess which orthosis designs are best at reducing the magnitude of internal first MPJ adbuction moment.

It would also be interesting to correlate HAA results to radiographic parameters such as:

1. Radius of curvature of 1st metetarsal head in transverse plane.
2. Sesamoid position on AP view.
3. Sesamoid position on plantar axial view.
4. Hallux abductus angle.
5. 1st intermetatarsal angle.
6. Metatarsus adductus angle.

This would provide us with information as to what structural parameters best correlates to causing a "hard to reduce" HAV deformity.

There is much more that could be done with this information. All we need now are some interested students/residents/clinicians that want to do something meaningful for the podiatry profession and their patients that wouldn't mind taking on this type of research project. It sounds already like Martin may be up to the challenge. This would be a great student/surgical residency research project!

 

Didn't do this as part of my PhD, actually got the idea from Eric when I visited the old CCPM, prior to our x-ray work. He'd got a supination resistance jig in his office. Made me feel good about myself that someone had got an office that was even more "organised chaos" than my own If you e-mail the picture to my home address Kevin, I'll add my scribble. I actually modified an old foot measuring board that had a 1.5" perspex rib up the middle to stabilise the medial side of the foot. BTW- I'd have liked to have seen at least one "ball swivel" in your sketch

I see where you are coming from Kevin, but this does not differentiate cause from effect, nor (as you obviously know) does it consider the external moments. Also, since we have no idea where the axis of rotation can we really measure the "internal moment"? I agree though, that as another measure it may be quite interesting and add to the body of knowledge. I won't hold my breath on finding "the cause" of hallux valgus having been there, and tried that! A longitudinal study would be interesting though to see how soft tissue changes influence the adduction resistance as the deformity progresses.

 

Simon


you said

just want to be sure I understand why or is this simply an inside joke?

thanks

Martin


Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com

 

Ignore, some things are best left alone.

 

Martin:

Attached is my original drawing of the STJ Axis Locator that I sent to Simon in 2001 before he constructed the world's first STJ Axis Locator. Simon then showed this drawing at one of the PFOLA meetings he lectured at, getting a pretty good laugh at the "ball swivel", which he said "sounded painful" to him, during his lecture. Simon can be funny sometimes.....igs:igs:

 

Simon:

The external hallux adduction moment will be able to be measured by the Hallux Adduction Apparatus (HAA). The vertical axis of the first MPJ can be estimated during nonweightbearing examination of the foot by adducting and abducting the hallux to find where the point of least rotation is on the first metatarsal head relative to an extension line from the bisection of the proximal phalanx of the hallux. The internal hallux abduction moment will be equal to the external hallux adduction moment when the HAA is not moving the hallux due to the principle of rotational equilibrium.

This test (i.e. HAA) could find utility in determining which orthosis modifications are best and which surgical procedures are best at reducing the internal hallux abduction moments. In addition, it would be interesting to see how increasing the external STJ pronation moment (e.g. adding a rearfoot valgus wedge) and increasing the external first ray dorsiflexion moments (e.g. by having the subject lean more forward) in the relaxed bipedal stance position would affect the results from the HAA. The possibilities for research are practically endless and seem, at least to me, to be much more useful biomechanically than doing radiological studies where one is looking at osseous shadows with no idea of the forces which are holding the osseous segments in that position.

 

OK thanks Kevin . .. . .. .. that explains it . .. . .. ... Jeeze you guys are easliy pleased

Here are a few snaps of the rig so far.

I have modified the base of my supination resistance force jig to use as a nice stable base.

I was surprised how little force was need to start hallux moving and how much play there is in the system , this being primarily from the cable stiffness. I am using 1/16 inch aircraft cable which is the thinnest I can get hold of locally.

I think this may be a problem and I will have to find a more flexible coupling. I’ll see what the data looks like which I am hoping to try out later when the missus gets home if she will let me borrow her foot. She still hasn’t forgiven me for the innuendo about the use of the skeletal foot which I keep under my pillow on the forum, gonna have to keep this less risqué.

Thinking about trying to get some data on 1st ray ROM; I have made a clamp which with a bit more work I think will allow me to use the rig to measure stiffness of 1st ray in sag plane. The clamp is constructed so that it a can be adjusted snugly around 1st MTH and pivot so that the force being applied via the test stand can be directed fairly tangentially to the met/cuneiform axis. I think if I fabricate a plantar support platform below allowing medial column to hang off edge, by stabilizing dorsal 2nd MTH with a thumb against the base I should be able to measure not only 1st ray excursion distally but also capture the incremental force/strain data too.

Any comments regarding stabilization of met/cun/nav/tal segement to isolate where the measured ROM is coming from? I was thinking of looking at this real time with US but maybe am getting a bit carried away.

BTW thanks Simon and Kevin for your input so far. It is much more enjoyable to feel that this a bit of team effort and that I can get a reallity check if needed too.

Cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com

 

Couple of interesting things with initial test of a normally aligned toe:

First perceptible motion occurred around 5N

System had way too much creep not just at low end but right through range. It seemed to take approx 5N to remove slack from linkages. I suspect some creep at the steel/nylon joint and looking at this now I can see why this was poorly designed. In spite of this the force/excursion plot looked pretty linear. This I also found interesting because it suggested that, at least for this joint, the tolerable limit of deformation was likely ligamentous not boney.

So back to redesign the connection from the force gauge to the toe. Perhaps try some braided metal fishing line now that I know what range of force needs measurement.

Otherwise the system seemed to work well; it has the potential to give some very precise measurement I think.

Max tolerated force was approx 50N with excursion of 16mm, this was higher than I expected.


Cheers

Martin

The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com