First of all, Dr. Assayag, thanks for posting on the forum and providing your insight. It is a rare opportunity to get to ask questions candidly to a LL surgeon outside of a consult when time is short and we are usually trying to focus on the individual goals of care.
I have read many journal articles about LL and different concepts in LL. From those I have several lingering general questions that I think only a LL surgeon could properly answer. Realistically no one is an expert in everything (even within a singular field), so I don't necessarily expect you to know everything about everything in LL, and this isn't meant to be a challenge or test. Mostly I'm just wondering what your general impression of each subject is if you're willing to share your perspective and experience.
These questions are not meant to be specific to any one doctor/device/method but just general questions about LL I have had trouble finding good answers on.
1) What is the best or most common way to fracture a femur?In
this thread, I reviewed a journal article that described the importance of the periosteum in callus production during limb lengthening. They state the periosteum contributes 83% of the callus to the healing bone which is of course an enormous percentage. Thus they say it is important to preserve the periosteum. This is probably especially true if you will be reaming and inserting a rod which will disrupt the intramedullary vascular supply.
Quotes in that thread from two LL doctors suggest they take a similar approach of trying to manually/gently saw the femur from the inside-out with a non-heat-generating intramedullary saw and then complete the fracture manually from the outside. Avoiding heat is important they say to avoid cauterizing the wound. In principle they say this approach best preserves the periosteum and blood supply which leads to faster healing.
What is your take on the best way to fracture a femur for leg lengthening? Do you think it is important to minimize damage to the periosteum? What is current conventional teaching in orthopedics programs on this?
2) Why is the Reverse Planning Method (RPM) not the standard of care to maintain ideal mechanical axis?As reviewed in
this thread, the Reverse Planning Method (RPM) allows one to anticipate the degree of mechanical axis deviation that will occur as a natural consequence of lengthening a femur. Because the femurs sit at an angle for all of us, any lengthening along the anatomic axis (length of the femur) will throw off the leg's mechanical axis (position of knee relative to line connecting hip socket to ankle).
In
one study posted there, this deviation was one degree for every one cm of lengthening. This means for 8 cm of femur lengthening, your axis might deviate by 8 degrees, which is obviously not an insignificant amount.
The original 2009 article explaining RPM is freely available here if sci-hub is not blocked in your country:
https://sci-hub.se/https://pubmed.ncbi.nlm.nih.gov/19685230/If you look at the
articles which cite the original RPM article from 2009, almost all seem to be Fitbone studies. This backs what one Fitbone doctor once said on this forum that the RPM is standard teaching for all Fitbone doctors.
One free article from 2019 talks about how to use the
Bone Ninja app for iPad to perform the RPM without having to manually trace the x-rays.
In terms of long term disability, barring obvious complications like nonunion or chronic pain, one of the primary concerns for all individuals who undergo LL should be early arthritis or wear and tear of the hips/knees/ankles. If someone is leaving surgery with an 8 degree deviation in the axis of their knees, I think it would be normal to expect that might be a consequence.
If the RPM can easily avoid this risk by maintaining a perfect axis, why is it not more widespread outside of the Fitbone teaching world? Do you think this something you think most LL surgeons are aware of and just don't reference by name? Is it something they avoid because they never were taught it during residency/fellowship (relatively new concept)?
3) Why are bone stimulation methods not routine in LL?As reviewed in
this thread, current meta-analysis shows bone stimulation with ultrasound (LIPUS) or magnets (PEMF) may result in 25% faster bone healing during limb lengthening. These devices cost a few thousand (minor compared to cost of LL) and must be ordered by a doctor. Patients cannot order them directly.
I have seen people use these when there is concern of a nonunion. However, that is like waiting for the car crash rather than trying to prevent it. Why do you think these bone stimulation methods are not common practice in all cosmetic LL patients? Do you think it is just a matter of them and the data being too new, and surgeons are not aware or not trusting of it yet?
4) Why do many orthopedic surgeons use fixation screws that go way past the bone and into soft tissue?As I discussed
here, many surgeons seem not too careful about the length of the fixation screws they use. This is not unique to LL but something I have observed about orthopedic surgeons in general and something I have always wondered.
It is not hard to do an intraoperative x-ray in orthopedics, right? In fact are such x-rays not common to confirm positions of implants and osteotomies? If an orthopedic surgeon (performing any orthopedic surgery) has preoperative x-rays, the option for intraoperative x-rays, and is placing screws that will be there for 2 years for a fee of $50-100K, why do you think some surgeons do not think it important to measure the length of their screws so they are not jutting 1-3 cm into the soft tissue?
Screws digging that deeply into a person's muscles every time they move will inevitably tear into that muscle, the nerves, the vessels, and cause pain and scarring. So speaking in general terms, if you have seen surgeons who are not mindful of this, why do you think that is? Is it just sloppiness? A lack of availability of different length screws? Or what?
5) If a surgeon is adequately monitoring the callus & a patient is healthy, why is nonunion ever a significant risk? Shouldn't this always be avoidable?As reviewed
here, one recent guideline on how to effectively perform LL suggests that x-rays should be performed every 1-2 weeks during distraction and the rate of distraction should be adjusted to maintain a 4-6 mm thick radiolucent (no bone visible) gap between the fragments during distraction.
Yet from what I've seen of pictures from patients during lengthening, I am not sure this is actually a widely used approach. I have heard some doctors suggest only once monthly x-rays are adequate during lengthening (which might mean only one x-ray every 30 mm). I have seen x-rays where people quickly extend and develop massive radiolucent gaps that luckily "fill in." With the PRECICE of course, there is the option to close the gap back down if it does not, but still, why should this ever be necessary or advantageous?
My instinct is if you are maintaining only a small gap like this all the way through distraction, you have no infections or underlying medical conditions, and your device is solidly fixated, there should be no reason for nonunions. If you never have more than a 4-6 mm gap, how could you get a nonunion? Why would some doctors want to go faster than that and create massive gaps knowing the risk? Even if you have a PRECICE unit, why take the chance? Why not go at the rate the body/guidelines suggest and be safe?
Is the radiolucent gap perhaps harder to appreciate with an intramedullary nail? Do you think most surgeons are mindful of this concept or not? Or what is your perspective?
Thanks for any thoughts you can provide. I know we all appreciate it.
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Topic: Five questions for Dr. Michael Assayag (less commonly discussed subjects in LL) (Read 917 times)