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If you search the site for "periosteum" there are only 5 hits that come up. Yet it is actually a critically important part of leg lengthening.

What is the periosteum? The periosteum is the connective tissue sheath that sits over top of your bone. It is the outer lining.

Why is it so important?

Preservation of periosteum as the main source of blood supply  is  critical  [46,75–81].  Its  disruption  significantly decelerates  bone  formation  [75,82].  Dual-energy   X-ray   absorptiometry   (DEXA)   and   histomorphometrical  studies  showed  that  the  periosteum  produces up to five-fold more callus than bone marrow during lengthening [74,75,88,89]. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3364349/pdf/11832_2012_Article_391.pdf

Yes, that's right: The periosteum (outer sheath of the bone) is making 5 times more callus than the bone itself during distraction. ~83% of your callus production comes from the periosteum. Only 17% comes from the bone.

They mention in that article early attempts at distraction in the 1920s failed because the surgeons completely severed the periosteum. Without the periosteum, there can be no bone healing from distraction.

One of the 5 hits that comes up when you search "periosteum" on this site is from an interview with Dr. Guichet where he states similarly:

"The periosteum is the element in a lengthening with a nail which is the only component from which bone is formed. So you need to preserve it, but if you cut it, your healing again will decrease strongly."

He talks about three methods for then breaking the femur and their pros and cons.

1) Osteoclasis - Breaking the bone manually without cutting. ie. Karate chop. In theory he says this is ideal which would make sense. If you do not cut the bone you will not need to cut through the periosteum. With a perfectly in tact periosteum, you should have rapid healing.

2) Cutting the bone with an intramedullary saw - Ie. Cutting the bone from the inside out when you are reaming. He says you can go 80% of the way from the inside out and then finish the job another way, ie. with karate chop (so as to still not cut the periosteum).

3) Standard osteotomy - Cut from outside to inside - This will inevitably cut holes in the periosteum leaking growth factors out into the surrounding tissue, blocking callus formation, and slowing or impairing healing.

He says:

"Opening a surgical site to the bone is aggressive and looses the bone healing progenitors. That is why I developed a specific intramedullary saw to preserve the healing hematoma. And that is in part why my patients heal so fast. Opening creates additional scars that patients do not like when they do cosmetic lengthening."

"Completing a fracture with hand maneuver (Karate Chop or whatever you call such a maneuver, as there are several technique for it) is obviously the best. It is called ‘osteoclasis’. It is generally performed on small bones, in children because it is easier to control through the skin without opening. "

"So, if you wish to preserve the fracture hematoma, you’d better not open the fracture site."

The interview with Dr. Guichet is here:

http://www.limblengtheningforum.com/index.php?topic=383.msg6514#msg6514

There apparently used to be videos of him there doing the karate chop which would have been interesting to see. According to that Paley uses a more traditional osteotome (chisel) to break the bone. Probably if he does wound the periosteum that way it's mild and he feels he can get away with it.

If you are talking to a surgeon about leg lengthening, one probably important question to ask them is: How do you go about protecting and preserving the periosteum? What types of cuts do you make through it during osteotomy?

Hopefully they have thought through their method and have a good one in place.

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I searched the other sections of the forum and found the following passage from Dr. Betz. It looks like he and Dr. Guichet have essentially the same perspective on this and prefer to do the fracture primarily via intramedullary saw. Then finish the fracture with mechanical pressure from the outside (karate chop, etc.).

It probably is no surprise these two have a similar perspective since they use a similar nail built off the same principles and original shared source model.

Here is Dr. Betz's explanation of this principle:

"In order to understand the bone healing, the so called osteoregeneration, basic knowledge about the bone’s supply are required: The area in which we have to do the lengthening - osteotomy the bone is supplied from both, the endosteum (the intramedullary vascular system) and the periosteum (the vascular system surrounding the bone).

Since the beginning of the Ilisarov procedure a great importance was awarded to the intramedullary vascular system. Because due to the cutting from outside regularly the periosteal supply of the bone was more or less comprimised.

However it has been shown that by even using the technique Ilisarov himself propagated (the corticotomy where only the compact bone is circularly cut) not only the the periosteal but also the endoosteal supply gets impaired. But still the researchers Brutscher and Brunner (working at institute of Davos and  concerned with osteosynthesis) have proven that even when the bone’s both supply systems are damaged, a regeneration can occur, it just requires then more time. Thus our goal must be to obtain both vascular systems.   

So if there is an indication for using an external fixateur, it makes sense to cut the bone gently from outside with one of the above mentioned techniques.

If there now an indication for the use of an intramedullary nail one still should try his best to maintain both vascular supply systems and thus choose an ideal cutting technique. Thank god there is no more discussion about the use of an intramedullary nail for a cosmetic lengthing (For two decades I’ve been now successfully preching about the advantage and significance of an intramedullary system).

Six decades of fracture repair with an intramedullary nail in lower or upper leg and in the upper arm have shown that the best way to reposition a fractured bone and to stabilize it, is the indirect approach, which means without touching the fractured area. The less we work on the fractured area the better the healing and the osteoregeneration process is.

The same applies for the lengthening osteotomy, since the cutting can actually be seen the same as a fracture.  The more careful we cut the bone, the better the healing process will be and the faster the bone regeneration starts and this of course has a huge effect on the post-treatment care.

That’s why I want to mention again both the internal and external supply systems of the bone: When introducing any intramedullary nail into the marrow hole we destroy the intramedullary vascular system. Of course the vascular system will recover after a certain time, but this is valuable time. Knowing this our highest priority must be to maintain the external supply system as sufficient as possible. Thus we do not touch the periosteal supply system from outside.

So obviously the only reasonable way to cut the bone is from inside using the same pathway one needs anyway to insert the intramedullary nail. Therefore we use different types of intramedullary saws. These saws are inserted into the intramedullary hole (which needs to be opened anyway to insert the nail) and cut the bone from inside. This saw cuts the compact bone from inside to a point where just small pressure from outside is enough to break the bone.

This means the periosteum doesn’t get touched. In almost 100% of our cases we are successful with this gentle method of cutting the bone and since we are using a manual intramedullary saw we also prevent heat production which as stated above also impairs the bone regeneration. Of course we also have electrical or air pressurized saws but we use them only rarely since they also produce a lot of heat which causes burns in the osteotomy region and thus slows down the healings process.

We only use the oscillating saw sometimes in lower leg surgeries for cutting the tibia. In contrary to the femur, where the marrow hole is in the center of the bone, in the tibia the marrow whole is located more dorsaly. The tibia is also triangularly shaped which makes is harder to cut the ventral part of the bone. Using an oscillating saw is then very beneficial.

I know that the intramedullary saw is not popular, since the surgeon using it requires a lot of skill and technical ability. But still I hope that my explanation showed you how reasonable the use of an internal saw is regarding the anatomy and physiology of the bone. Especially if you use an intramedullary nail."

http://www.limblengtheningforum.com/index.php?topic=132.31

I would be curious how widespread this approach is and what other surgeons are doing to try to preserve the periosteum. Are all surgeons using intramedullary saws to make their cuts? Or are most cutting from the outside in, and damaging the periosteum every time in the process?