What is the Optimum Angle of hallux after 1st MPJ arthrodesis

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Hello all

Wasn't sure whether to post this in biomechanics or surgery!

Anyway, I have a female patient 60yrs old who had a 1st mpj arthrodesis oct 2009. She had a very painful joint which is now painfree, in that respect it has been successful.

She came to see me in Dec 09 because she found walking difficult. I made alterations to her orthoses that I had made several years earlier. The mods were to accomodate the hallux, which I felt was fixed in a far to plantarflexed position. I also added a rocker bar to her shoe. This helped with mobility.

On return to her surgeon for follow up he told her he would prefer her not to use any shoe or insole and to weight bear on the toe until it was ok (she would get used to it).

She has returned to me to see if I can help. I note that she has adapted her foot position to accomodate the plantarflexed hallux i.e. she supinates the foot.

This is what I felt was not right about the final position of the fixed hallux:

The declination angle of the 1st ray is 20dgs relative to the ground plane. The hallux is dorsiflexed 5dgs -10dgs relative to the 1st ray (depending on how hard you push on the hallux to dorsiflex it. i.e. 10dgs is the most optomistic angle)
Therefore the hallux is actually plantar flexed relative to the ground plane by 5 - 10dgs. (see diagram).



Surely this is not correct since this allows no rocker action at the MPJ during propulsion.

ref- A Guide To First MPJ Arthrodesis For Active Patients
VOLUME: 18 PUBLICATION DATE: Dec 01 2005 Lawrence A. DiDomenico, DPM, and Alfonso A. Haro III, DPM quote "Temporarily fixate the hallux by utilizing two K-wires in the desired position. The position should be approximately 20 to 30 degrees dorsiflexed in relation to the first metatarsal declination"

What are your thoughts? As I'm no surgeon perhaps there is good reason for this hallux position?? Do you think I should make a shoe/orthotic to accomodate this and improve her walking or should I think about referring her back to her surgeon for corrective surgery.

Cheers Dave

 

This is a common sequela of an arthrodesis. The angle of dorsiflexion of the toe must be 'greater' than the angle of declination of the 1st met.

How much greater depends on the degree of activity engaged in, the more active the more the angle of dorsiflexion. At the angle described it won`t be long before problems occur in the ip joint, the toe is jamming and stoppng normal push off.

The non surgical answer is a form of rocker sole, this is a poor substitute for having the angle in an acceptable position. The patient will get around this by lifting the knee when walking, as this is one sided other problems will likely occur on the other side !

 

Dave:

No good podiatric surgeon that I know uses the 1st metatarsal declination angle to decide where to fuse the 1st metatarsophalangeal joint (MPJ). Rather, most podiatric surgeons that I know (including myself) use the angle of the hallux to the ground intraoperatively to determine optimum sagittal plane position of the hallux for 1st MPJ arthrodesis procedures. Generally, if the hallux proximal phalanx is fused about 10 degrees dorsiflexed relative to the ground, this creates an excellent position of the hallux for walking in normal shoes up to a 1" heel height differential and also for running. However, if the hallux is fused plantarflexed, this will create significant foot and postural issues long term. Tell the patient to look for another surgical opinion from a better foot surgeon.

 

It depends on what the patient wants really. Like the other guys on here have said, you can carry on with a variety of conservative options, or potentially refer for surgery. Kevin Kirby made the point that you might want to consider referral onto another surgeon for an opinion and I'd tend to agree - perhaps the first surgeon had his book upside down when he was reading where to position the hallux in the sagittal plane? :wacko:

It's pretty straightforward and you don't have to be a surgeon to recognise that a hallux fused in a plantarflexed position (relative to the supporting surface) is not the right way to perform a fusion. I'm constantly amazed to see that people can get these simple things so wrong (aimed at the original surgeon). It's not rocket science.

If I saw this patient (depending on x-rays) for a surgical opinion, I'd be looking at offering a dorsally based closing wedge osteotomy to the (former) base of the proximal phalanx once I'd removed whatever fixation is in there from the fusion (similar to Kessel Bonney). It'd be a relatively simple procedure and should have a good result - but then again I am saying this with the benefit of seeing the situation through the internet and I'm not party to the full picture. The patient may loose a small amount of length from the toe, but not usually a significant amount. Hope it goes well.

 

Kevin

Thanks for the paper just what I wanted.

Bob

Thanks for the reply, I was thinking exactly what you and Kevin have said but for me to refer to a second surgeon I have to be on a good foundation. Sometimes there can be a good reason for something that is not immediately obvious. The patient would probably want to take up the situation with the first surgeon since she already feels a bit hard done by because she can't walk properly. I wouldn't want to be in the middle with a weak case.

Many thanks Dave

 

Kevin

I don`t think it was suggested that the 1st metatarsal declination angle was used to decide where to fuse the 1st MPT but simply that it was the angle Dave found in the quoted case.
What method was used, if there was one, we don`t know.

You say that you fix 'about 10deg', is that in all cases or are there cases where you substantially vary that angle ?

Regards

 

Rosher:

I never said how the surgeon in question made their decision as to why they would fuse the hallux more plantarflexed than normal. What I did say is how good podiatric surgeons make their decision for hallux angle for 1st MPJ arthrodesis procedures.

I would tend to increase the 10 degree angle only if the patient preferred to wear shoes with heels greater than a 1" heel height differential. I try to talk them out of these shoes since, when barefoot, the toe will not look cosmetically as nice as the 10 degree angle arthrodesis.

 

That really bothers me. A surgeon who does not understand what is going on, or doesn't want to admit to what is going on. You wonder if he mentioned possible overload of the tip of the hallux when he obtained an informed consent for the surgery. "Youll get used to it."????? There's a problem there.

Regards,

Eric

 

Quite :bash::craig:

Dave

 

Arthrodesis of the First Metatarsophalangeal Joint: A Robotic Cadaver Study of the Dorsiflexion Angle
Ahmad F. Bayomy, Patrick M. Aubin, Bruce J. Sangeorzan, and William R. Ledoux
The Journal of Bone and Joint Surgery (American). 2010;92:1754-1764.

 

Foot function after fusion of the first metatarsophalangeal joint.
van Doeselaar DJ, Heesterbeek PJ, Louwerens JW, Swierstra BA.
Foot Ankle Int. 2010 Aug;31(8):670-5.