Stability and healing of bimax CCW surgery with posterior down grafting

[Dogmatix]

What does the situation look like a year after such surgery? Is it like you break a bone, put plaster on it and the body regenerates new bone completely? Or is it a long term stability issue where it doesn't really heal, but you're dependent on the grafting materials and the plates to hold it up?

I suppose it may be different for the mandible and maxilla? The mandible with a BSSO cut seems pretty straight forward. You fracture the bone and it heals in the new position?

But what is the situation for the maxilla? Will the bone regenerate to fixate the maxilla in the new position, or is it the grafting material that holds the distance at the posterior part of the maxilla down for all eternity, and the plates to stabilize?

I've heard people going in for a second surgery to remove the plates and screws because of different reasons. Is this possible for this kind of surgery, or may that cause a collapse at the posterior down grafting?

I've read some studies saying that posterior down grafting is stable now days, but it's still interesting to know if that is just because the plates and grafting material stays stable, or if it's a complete healing. And also with "stable" in these reports, it seems like there is some movements, but within the range that is considered stable.

[kavan]

BOTH the maxilla and mandible are BONES that are FRACTURED and would go through a biologically similar healing process.


According to a medical website on bone fracture healing, the first thing they point out is:

"Fracture healing involves a complex and sequential set of events....."

https://www.orthobullets.com/basic-science/9009/fracture-healing

Your statement posits this complex healing process is 'straight forward' (to you?) when the fracture is to the mandible.

I can't answer your question in the way you present it. What I can do is tell you the following:

1: BOTH the maxilla and mandible are BONES that are FRACTURED and would go through a biologically similar healing process which would be considered a 'complex' one unless someone is really conversant in bone biology.

2. In terms of reducing things so they are more straight forward or 'intuitive' in the absence of being conversant in this complex and sequential set of events that transpire during fracture healing, we would look for more commonalities that relate broken bones to 'fixing' them in place. For example, plates and screws which keep the bones in place while they 'heal' (which can be removed after the bones have stabilized). So, both the maxilla and mandible have in common that they both need to be fixed in place.

3: As to the reason(s) plates and screws are removed later down the line. Sometimes it's because of an infection. Other times it's because they are not needed anymore after they've done their job stabilizing the bone in place. Since bone 'healing' involves osteoblasts (generation of bone), bone can form an overlay to the plates which would make them harder to remove later down the line if they got infected.

4: In the case of a bone 'graft', it's done so that the cut area of the bone(s) have CONTACT with a POROUS material they can INTEGRATE with. If it's a posterior downgraft, it's kind of like a wedge shape as to 'wedge down' the posterior maxilla to affect CCW. Bone 'grows' INTO the pores of the porous material so that the material becomes INTEGRATED with bone.

So, plates and screws are used to FIXATE the bones in place UNTIL they 'heal' or become stabilized in that position so the plates and screws are no longer needed. The posterior down graft also needs to be fixated until bone cells (and/or other cells that go along with bone healing) INTEGRATE with it so that it becomes stable.

[Dogmatix]

Thank you kavan.

So basically it seems like any stability and relapse issue would be during the healing. When the healing is done, the situation would be considered static. So it's up to the patient not to load the maxilla with heavy chewing.

The reason why I assumed it may be different for the maxilla than the mandible is that it seems like a far more complex situation with the maxilla. I've never heard anyone talking about needing grafting material for the mandible, they just fracture it, move and fixate for healing. But in the maxilla, it's not a simple fracture, the bone goes like a half circle around the airways and other important "stuff" that should not be interfered with.

It sounds like, with strong enough fixation of the maxilla, there wouldn't be a need for grafting material, it could just be left for healing in the new position like the mandible?

What has the history for posterior down grafting looked like? When reading around it seems like it's a stable technique for the last 10 years, but why wasn't it stable before? What mistakes were they doing then that caused it to relapse, and what is it in the new techniques that makes it safe?

[kavan]

Thank you kavan.

So basically it seems like any stability and relapse issue would be during the healing. When the healing is done, the situation would be considered static. So it's up to the patient not to load the maxilla with heavy chewing.

The reason why I assumed it may be different for the maxilla than the mandible is that it seems like a far more complex situation with the maxilla. I've never heard anyone talking about needing grafting material for the mandible, they just fracture it, move and fixate for healing. But in the maxilla, it's not a simple fracture, the bone goes like a half circle around the airways and other important "stuff" that should not be interfered with.

It sounds like, with strong enough fixation of the maxilla, there wouldn't be a need for grafting material, it could just be left for healing in the new position like the mandible?

What has the history for posterior down grafting looked like? When reading around it seems like it's a stable technique for the last 10 years, but why wasn't it stable before? What mistakes were they doing then that caused it to relapse, and what is it in the new techniques that makes it safe?

To the best of my knowledge the docs tell the patients about taking it easy on the chewing.

The complex biological healing mechanisms for fractured bones were gone over on the website I gave. The cascade of biological sequences for the 'healing' is similar. But of course, there are different kinds of fractures and/or WAYS to BREAK bones where what I would call  'MECHANICS' would factor in. For example bone cells to go from one broken part to the other can't travel over a large GAP. They have to have CONTACT connection which is WHY a GRAFT is wedged in for posterior CCW of the maxilla so the bone cells can INTEGRATE (grow into) the PORES of the grafting material. SO, NO, NO, NO. You can't just leave a LARGE gap when the posterior part of the max is dropped down via CCW. The EXPOSED areas would have NO CONTACT and hence there would be RESORPTION of bone because there is no contact and the GAP would be too large for the bone cells to travel across. HENCE a GRAFT to fill in the GAP left the drop.

[Dogmatix]

SO, NO, NO, NO. You can't just leave a LARGE gap

Thanks for the clarity on this