How LL (inevitably?) misaligns joints, creates x-legs, and causes joint pain

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Well in the old forum they already wrote about this. The name of the topic was: Bow Legs & Knock Knees Correction

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Quote from: Wazzup on April 11, 2015, 01:36:25 AMWell in the old forum they already wrote about this. The name of the topic was: Bow Legs & Knock Knees Correction

Just read that thread. It looks like it was just a very general discussion of how major varus and valgus deformities can be corrected in orthopedics. It's not really touching on our specific points ITT.

I'm still laying claim to the idea of performing distal femoral opening wedge osteotomies as part of routine practice during nail removal for internal femoral leg lengthening.

If this catches on, remember, you saw it here first.

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Quote from: KiloKAHN on April 11, 2015, 12:55:39 AMI'd still do external tibias all over again before doing them internally. At least if you go to a doctor that offers a Taylor Spatial Frame or a six-axis correction system like a hexapod, your doctor can do a perfect realignment with the computer software once the lengthening is complete.

KiloKAHN, I just read your thread. Wow. Thanks. I didn't even know such advanced external tibial fixation devices existed. Based on that I think the two best approaches for preserving/correcting axis during leg lengthening could be in order:

1) Tibial Taylor or Hexapod - If you can wear it 8 months to lengthen 6 cm and don't mind the pins/apparatus.
2) Internal Femurs with Distal Femoral Opening Wedge Osteotomies (DFOWO) - Faster with bigger gains, and still with good post-op alignment, although as proposed above, this option doesn't technically exist yet.

I would guess the Tibial Taylor/Hexapod approach would be slightly superior in terms of final alignment given that they can be fine tuned by computer. With the femoral method I suggested, the surgeon's hands are the final arbiter of your alignment, so there is opportunity for human error. Additionally, the Internal Femurs with DFOWO approach will still by design force a mild probably 1-2° abduction (opening) of both hips. I don't think that would cause any issues at all, since the hips are freely ball-and-socket. But this abduction is avoided with a strictly tibial approach, so from a purist perspective on alignments, a computer assisted external tibial approach might probably be most ideal (though very slow).

Do you know anyone using the Taylor device for cosmetic leg lengthening? It looks more advanced than the Hexapod.

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I don't know of any diaries where a TSF was used. They're quite expensive so I'm told they're not usually done for simple lengthenings. You might end up paying around the same price for a TSF as you would for an internal device.

As far as I know the hexapod does the same exact thing, according to my surgeon, who's used the TSF before when they were donated to him from a UK clinic. I'm guessing the main difference is the material it's made out of. But they both use computer software and are six-axis so the result would be the same.

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I've looked a bit more into the subject of using distal lateral femoral open wedge osteotomies to correct the valgus shift that can be induced by internal femoral lengthening.

For anyone that's interested in details, a full article is here describing the procedure in depth:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2899363/

To illustrate again what a valgum looks like (a, b) and what a distal femoral opening wedge osteotomy can do to recreate an ideal alignment (c), here's one pic from the linked article:



Here's a small diagram showing the hardware:



The main points I've learned from reading about the procedure are:

• This can be an exceptionally precise procedure. The angles are all planned out in advance. A small metal spacer (eg. between 5-17 mm) can be introduced to the edge of the osteotomy to guarantee you are getting the amount of wedging you want.
• Primary risk is incurred during the "splitting" process to open up the osteotomy. This risk is that if this is not done cleanly/well, the bone can just fracture straight through. Not sure what the probability of this is. Probably very low in healthy bones. But obviously you'd want someone who's done this before operating on you.
• Big point: In order to protect the alignment post-osteotomy, it's suggested that are completely non-weightbearing for 4 weeks, and 6-8 weeks total to get back to full normal weight bearing, or as x-rays indicate consolidation has occurred.
  

My final impression is that this procedure is the definitive solution to the potential problem of valgus shift during internal femoral lengthening. It could be best applied by getting the internal femurs done and then rehabbing for 1-2 years. After 1-2 years, if the valgus is significant/bothersome (or the individual worries it will in the future), nail extraction and distal femoral opening wedge osteotomy are booked to occur during the same procedure.

I don't know what Dr. Guichet's or Dr. Paley's experience with performing this kind of osteotomy would be. I'm guessing they would be capable of performing it, but probably haven't done it much before since it's not their field of expertise. If so, if it was me, I would probably see if I could get another surgeon with expertise in this to attend during the nail extraction and perform it with Dr. Guichet/Paley assisting.

It's a tossup for me between going this route vs a comparatively noninvasive approach like tibial Ilizarov with Hexapod.

The internal femurs even with time for the corrective wedge osteotomy is probably going to be faster. With Guichet, it's almost exclusively weightbearing. The femur approach also allows you to still wear heel lifts for another 1-2 nonsurgical inches without it looking ridiculous. The main downsides of this approach are first that the realignment osteotomy will require two months of downtime. Plus then you've got permanent hardware in your knee, or you have to go back for a third operation to remove it. It also involves a lot of drilling/cutting into the femurs.

By contrast, the Ilizarov with Hexapod is comparatively noninvasive with very little cutting/drilling. I also personally prefer the look of long tibias. But it's very slow for comparable gains, such that even with good progress, at 10 months you can still have your frames on. Plus you have to spend 6-8 months under medical supervision in a foreign country.

It's a tough decision. Both approaches should maintain the hip/knee/ankle axis well. But they are very different pathways. Thoughts?

For my own part, I think I am leaning towards internal femurs, perhaps weightbearing with Guichet, and then following that with a slight realignment osteotomy in 1-2 years during nail removal if needed.

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You don't think the wedge will make it easier to get femur fractures or anything? It looks like they'd be more sensitive to that sort of thing when you cut a bit of the bone out.

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Quote from: Sean Connery on April 12, 2015, 12:59:02 AMYou don't think the wedge will make it easier to get femur fractures or anything? It looks like they'd be more sensitive to that sort of thing when you cut a bit of the bone out.

You are not actually cutting a bit of the bone out. Cutting the bone out would be a "closing" osteotomy. That would cost you height. The beauty of the "opening" osteotomy, is you are doing just that - opening up more space, and thus you will actually gain at least a few more mm through the procedure.

Here is a picture of how the "opening" is done:



As long as everything is well fixated together when done, you should ossify the few mm gap on your own within the 8 weeks or so they suggest for sufficient recovery. But that is why you must be nonweightbearing for at least 4 weeks post op.

In the case of a big valgus deformities, where you need more than 7.5 mm wedging, they suggest using a small bone graft from the iliac crest (where bone grafts are usually harvested from) to fill the gap and prevent nonunion. Below 7.5 mm it depends who you ask they say whether there is still benefit from grafting or if it is fine to just leave it open with just the metal spacer and it will fill easily enough with bone on its own.

I expect it should be fine for most of us with no graft at this small a wedge, because as a wedge, it will start to fill from the narrowest aspect and continue outwards from there. I suspect a graft would only be universally necessary in, for example, an elderly woman with poor bone/healing quality.

I'm not sure which category we'd typically fall into in terms of how much correction we'd need. It would be easy enough to calculate though with some simple math though, and I will do this at some point in the future.

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I had a thought...

You're showing the effect of mechanical axis deviation from norm, when someone is standing with their feet together. So as we've figured the tibia is angled 0 degrees, but only when standing with your legs closed (obviously deviatons also occur). When you spread them apart, tibia gains more angle. So what happens when you lengthen femurs internally is that you just have to spread your legs more to put feet together now. Where I was going with that... You don't usually see people standing with legs completely closed feet together, right? That means their tibias are already angled and in comparison with someone who has done internal femurs, it would be no different angle, because you're standing with your legs apart anyways. Now you could say: it's walking that matters, not standing. Lets think about that...




So they're walking with their legs spread, knees not connecting together, feet are more spread in the first video.


Now imagine if they lengthened 7 cms in their femurs along anatomical axis. As their feet and knees aren't being put together, which should btw mean that they are walking with an angle in their tibs as is, they shouldn't feel too much difference after LL. What do you say? I think your mistake was basing all your assumptions on a model of someone standing with their feet together, which is when the tibias are angled 0 degrees.

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I'll clarify a bit:

The mechanical axis is defined as a straight line going through the femoral head and the middle of the ankle joint. In a well aligned leg, when you draw a line connecting the middle of the femoral head to the middle of the ankle, you will also go straight through the middle of the knee:



This alignment is important, because having it means the primary points of load bearing of the leg will pass weight and hinge efficiently (femoral head, knee, ankle). According to eMedicine "the mechanical axis averages 1.2° of varus". This means the line that goes through all these weight bearing points when you are standing in a natural position is for most people on a tiny 1.2° varus tilt relative to the perpendicular.

If you start with a good mechanical axis and then lengthen along the axis of the femur, you will inevitably throw these three points of alignment out of wack into a mild genu valgum (as per my diagram in the OP). You will be misaligned when standing in any position and even when walking. Whether you will notice this or it will cause damage to your joints may vary from person to person. I posted explanation and evidence for why I believe it has the potential to be a significant long term problem on page 4.

The only way I can see to properly get the alignment back after such internal femoral lengthening is to do a distal femoral opening wedge osteotomy to the lateral aspect of the femur during follow up as described above. (Or the other valid option for maintaining the axis is to avoid the femurs altogether and do, for example, internal tibias or Ilizarov tibias with Hexapod. But as discussed, those options both come with other challenges.)

I can perhaps put together some proper Photoshops in the future if this doesn't make it clear.

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I know what mechanical axis is. I don't think you understood what I was talking about. In fact, you ignored all of the points I've made.

Initially you were claiming that after lengthening femurs along anatomical axis, "spacing feet naturally now creates angulation to joint lines". But you're looking at only one position (feet together) and also ignoring the fact that you're going to have the very same 'angulation to joint lines' if you stand in ANY position other than the initial one with your feets closed. Let me show...


Here we have someone standing with their feet together, no angulation to joint line, right? We have a perfectly straight line. But then he spreads his legs/feet apart...



And now he has the very same angulation in knee joint, which he'd get after IFL. And I could also argue that this position is more natural and usual, than the one with feet together.