Lengthening limits and anatomical axis

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Quote from: Michael J. Assayag, MD on October 28, 2020, 07:50:31 PMIt depends on one’s lengthening philosophy.

I rarely perform cosmetic retrograde lengthening unless correcting a deformity concomitantly. There is no way to correct a deformity and do an antegrade lengthening , unless the deformity is at the top.

Baumgart from Munich only lengthens in a retrograde manner using his reverse planning method.

I am currently analyzing radiologic results of close to 300 femoral nails lengthened along the mechanical axis. My hypothesis is that the lateralization of the mechanical axis is offset by the bend in the nail at full distraction for most commonly used nails

Makes sense, thanks for the answers. So is there any studies done on knee pain from retrograde insertion?

Also for your research, do you mean that because of nail bending femoral lengthening won't cause X legs (meaning there is no shift?)

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Quote from: MakeMeTallAF on October 29, 2020, 03:54:42 AM

Also for your research, do you mean that because of nail bending femoral lengthening won't cause X legs (meaning there is no shift?)

exactly!

as for knee pain. There is a pretty good study by Peter Giannoudis in Bone and Joint Journal 2006:

Retrograde femoral nailing.

In this group, there were five retrospective studies,44,55,56,58,61 seven prospective studies,32,42,43,46,53,54,60 two case studies49,57 and one systematic review of the literature59 giving a total of 516 fractures. The mean follow-up was 15.9 months (956 to 2446). The mean incidence of knee pain was 25.6% (1.1%43 to 55%57) at the end of the follow-up. The most common causes of knee pain related to RFN were the protrusion of distal locking screws and impingement of the nail on the patellar tendon and/or the articular surface of the tibial plateau. In the very few cases in which the metalwork had been removed, there was an improvement of the symptoms in all of the six patients in the study of Gellman et al55 and the one patient in that of Herscovici and Whiteman.46



Meaning pain in retrograde nailing is mostly related to hardware and improves upon removal. this has been studied for trauma

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Quote from: Michael J. Assayag, MD on October 29, 2020, 01:05:41 PM

Meaning pain in retrograde nailing is mostly related to hardware and improves upon removal. this has been studied for trauma

Awesome, thank you Dr. Assayag!

One quick question, is there any studies on incidence of pain during antegrade nailing? Is antegrade nailing typically better for long term outcomes?

Also please do update us when your paper is published, it will be interesting to know the results.

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Dr Assayag I posted another thread about something similar to your research, it was a quote from a surgeon name Dr Franz Birkholtz who said the following regarding lengthening over 5-6 cm in femurs leading to malalignment.

Quote from: Franz on March 12, 2014, 07:09:54 PMYes 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.

Is your opinion that this does not happen and malalignment will not occur for patients lengthening over 5-6 cm in femurs according to your research? Secondly regarding the 15% lengthening limit do you apply that to tibia lengthening or do you have a hard 5cm limit? Thanks

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good question.

My experience is that we do not create malalignment. The result of my paper in stature lengthening with Dr. Rozbruch tends to confirm that as well, although it only includes 15 patients.

In terms of hard stop at 5cm, I do not have a hard policy about it, as long as the knee and ankle can tolerate the lengthening, as long as the nerves can tolerate it, and bone quality remains good. If all those conditions are met, I agree with continuing lengthening and monitor closely.

However, I am all in favour of managing expectations and that’s why I usually quote 5cm as attainable target for tibia lengthening.

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Interesting. As you mentioned the bend in the 10mm and 11.5mm what happens to patients who would need the 13mm stryde?

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It depends on their weight.

A 13 nail for stature lengthening is not the most common although it happens that the anatomy requires it.

Even if it doesn’t bend , the change in mechanical axis is minimal.

However if the native alignment is knock kneed (valgus), It may have to be addressed

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Excuse me dr but what outcome do you expect when you say "5cm as attainable target for tibia lengthening" will you be able  running, treking,etc after an apropiate recover?
sorry my english not my native language

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very informative

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Quote from: Bushguy on November 03, 2020, 04:56:26 PMExcuse me dr but what outcome do you expect when you say "5cm as attainable target for tibia lengthening" will you be able  running, treking,etc after an apropiate recover?
sorry my english not my native language

Thats precisely what I mean.

I mean that 5 cm will predictably create good bone, may not create nerve issues, and if well done, will not create knee and ankle contractures.

Once the bone heals, full activities may be resumed.