Limb Lengthening Forum
Limb Lengthening Surgery => Height & Proportions => Topic started by: thetallerman on March 12, 2014, 12:38:02 PM
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Hey guys since Femurs do not run straight up and down like the tibias as seen in this picture (attached) but in fact run at a slanted angle, if you were to lengthen for example, 5 cm in them, would the actual gain be 5 cm, or it would it be more or less? Can math whizzes help me out on this and also give the reason behind their answers. Thanks guys and looking forward to the responses. It's just I would hate to lengthen a certain amount and then when I measure myself post-lengthening I don't get the amount I thought I would.
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and to clarify, by "gain" I mean, when you measure yourself against the wall, for example, would you be 5cm taller or would it be more like 4.9cm or 5.1cm or even more/less?
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Logically the height gain would actually have to be less than the ammount lengthened, although im not sure how much difference, it depends on how angled your femurs are
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Logically the height gain would actually have to be less than the ammount lengthened, although im not sure how much difference, it depends on how angled your femurs are
Yeah that would make sense, I'm wondering by how much though. Because if it's .1, .2 or even .3cm+ that one would lose, I'd then need to make sure to lengthen slightly more than planned to meet my goals.
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I can say from my experience. I lengthened 7cm and the gain was 6.5cm. You will always loose some mm in height, even if you had a smooth lengthening, for a lot of reasons. Most of the guys I know gained in height 0.5 - 1cm less than what they have lengthened.
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I can say from my experience. I lengthened 7cm and the gain was 6.5cm. You will always loose some min height, even if you had a smooth lengthening, for a lot of reasons. Most of the guys I know gained in height 0.5 - 1cm less than what they have lengthened.
Wow that's a pretty significant loss. I guess I'll just have to make myself stand up every so often during lengthening and measure myself against a wall to see the true height achieved at that point.
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I can say from my experience. I lengthened 7cm and the gain was 6.5cm. You will always loose some mm in height, even if you had a smooth lengthening, for a lot of reasons. Most of the guys I know gained in height 0.5 - 1cm less than what they have lengthened.
Who did you get your femurs done with if you don't mind me asking? And thru what method?
That's pretty significant but not surprising to me. The femurs are very curved and slanted, which means the bone can lengthen all it wants but the actual height realized is always going to be less.
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I can say from my experience. I lengthened 7cm and the gain was 6.5cm. You will always loose some mm in height, even if you had a smooth lengthening, for a lot of reasons. Most of the guys I know gained in height 0.5 - 1cm less than what they have lengthened.
Just making sure since you didn't say, did you do femurs or tibia?
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So it is a good idea to lengthen 0.5-1 cm more. Less height from external pin bending is understandable but internals? It will be a good idea to ask a LL surgeon about this!
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This is why the standing x-ray is important no matter how you're lengthening. Looking at the gap or counting clicks/turns doesn't tell the whole story regarding standing height. Measuring the legs in the before/after standing x-rays straight up and down will tell you how much height you gained.
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This is why the standing x-ray is important no matter how you're lengthening. Looking at the gap or counting clicks/turns doesn't tell the whole story regarding standing height. Measuring the legs in the before/after standing x-rays straight up and down will tell you how much height you gained.
Would this be a problem lengthening with a non-weight bearing nail? Standing xray while lengthening with PRECICE doesn't sound like a good idea to me.
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Yes with exfixes we lengthen along the mechanical axis which should correspond pretty much to patient height. With femoral nails, we tend to lengthen along the anatomic axis, which might not correspond perfectly to height gain (it is oblique). It is well described too that patients end up with 5-10 mm less than expected. I would suggest going 1cm beyond target length and then backing the nail up by 5mm. This would ensure quick consolidation. The downside of long lengthenings along the anatomic axis (like with precice, guichet, betzbone, iskd), is that we change the mechanical alignment of the femur, as we lengthen along a different axis. This means that intramedullary lengthenings in the femur beyond 5-6cm will inevitably lead to slight malalignment. This may in time lead to arthritis.
In short, keep to reasonable distances and go to a doc that understands this.
Standing xrays can be taken with Precice nails with certain precautions.
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Who did you get your femurs done with if you don't mind me asking? And thru what method?
That's pretty significant but not surprising to me. The femurs are very curved and slanted, which means the bone can lengthen all it wants but the actual height realized is always going to be less.
Femurs-Albizzia
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Mathematically, it wont be the same because of angle, I can measure the loss if you give me the original length of femur before the lengthening, and your x-ray..
I did femur lengthening along with tibia lengthening, despite I lengthened the same amount for both part, but my tibia looks longer .. so maybe that due this reason,.
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Mathematically, it wont be the same because of angle, I can measure the loss if you give me the original length of femur before the lengthening, and your x-ray..
I did femur lengthening along with tibia lengthening, despite I lengthened the same amount for both part, but my tibia looks longer .. so maybe that due this reason,.
How much did you lengthen in your femurs? And how much actual height did you gain?
I want to get anywhere between 6.7cm to 8cm of actual height gain from my femur lengthening which will get me to 5'9.5 to 5'10, want to be at least average. However, I'm thinking those numbers might have to be revised to 7.7cm to 9cm to compensate for possible lossage of up to 1 cm, which worries me a little because I don't want to do 9cms of lengthening, past the normal safe zone, really confused on what to do, might just have to lengthen and take it day by day, see what my doctor says, and see what my body can handle.
Also I'll give you exact lengths/xray of my femurs when I have them, thanks!
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Yes with exfixes we lengthen along the mechanical axis which should correspond pretty much to patient height. With femoral nails, we tend to lengthen along the anatomic axis, which might not correspond perfectly to height gain (it is oblique). It is well described too that patients end up with 5-10 mm less than expected. I would suggest going 1cm beyond target length and then backing the nail up by 5mm. This would ensure quick consolidation. The downside of long lengthenings along the anatomic axis (like with precice, guichet, betzbone, iskd), is that we change the mechanical alignment of the femur, as we lengthen along a different axis. This means that intramedullary lengthenings in the femur beyond 5-6cm will inevitably lead to slight malalignment. This may in time lead to arthritis.
In short, keep to reasonable distances and go to a doc that understands this.
Standing xrays can be taken with Precice nails with certain precautions.
That is very, very interesting. So with monorails for example, since it's running along your leg, when you have made the turns for 1mm, for example, your actual height gain should be about 1mm since it lengthens along the leg vs the anatomic axis of an internal nail!?
I'm strongly considering doing monorails lately, Dr. Mahboubian does them and he lives like 3 hrs away (driving), they are much cheaper than precise, I can get a nail put in after lengthening so I can weightbear while recovering. Monorails are more painful though right, because of those large pins? The thing is I've had pain in my life, nearly exploding appendix felt like I was dying, so the pain of ll doesn't scare me as much.
I'm getting mixed comments on how far you can go for weightbearing on monorails though before you have to start relying heavilly on crutches/wheelchair, think it's somewhere around 5 or 6cm. And is that because it's hard to walk or because the monorail might actually not be stable at that point, possible breakage? Advice, knowledge on this guys?!?!
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The monorail patient I met in Beijing had to rely heavily on his wheelchair from the very beginning due to muscle weakness and pain. I never even saw him use a walker or crutches.
I don't think that monorails become unstable after lengthening a certain amount, as long as you're using a nice and sturdy device.