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Distraction osteogenesis is a surgical process for
reconstruction of skeletal deformities. It involves gradual, controlled
displacement of surgically created fractures which results in
simultaneous expansion of soft tissue and bone volume. It is the ability
to reconstruct combined deficiencies in bone and soft tissue that makes
this process unique and invaluable to all types of reconstructive
surgeons.
Bones of the
face can be acutely moved significant distances and grafted to produce
predictable results. Ten years of distraction osteogenesis (DO) surgery
has showed that surgeons can produce equally dramatic results with
simple osteotomies followed by slow distraction of the bone segments.
The biological principles
behind distraction osteogenesis are sound. A simple osteotomy followed
by a latency period, then active stressing of the bone and soft tissue
by distraction will predictably produce new bone and soft tissue once
the consolidation period has elapsed
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| Pre Operative Images |
Post Operative Images |
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1. Length of
advancement: Close examination of the cephalometric radiograph
demonstrates that prior to the maxillary surgery the amount of
mandibular advancement is significant (12 mm). Post LeFort I
osteotomy and impaction of the maxilla this figure is actually
increased to approximately 15 mm because as the maxilla is impacted,
the mandible must advance farther in the sagittal plane to provide a
Class I occlusion. A 15 mm advancement in a 38-year-old can be done
without a bone graft; however, with such a significant advancement
of the mandible there may be insufficient overlap of bone to provide
adequate surface area for rigid fixation. Additionally, such a major
advancement of the mandible can have significant relapse. The
gradual separation of bone & soft tissue in DO is believed to result
in little, if any, relapse. Although I have observed no relapse in
my advancement patients thus far, long-term follow-up studies are
needed to confirm this claim.
2. Bone structure of
the patient: Examination of the preop Panorex and cephalometric
radiograph demonstrate that BB has a high mandibular plane angle and
thin condylar neck. These two findings in association with the
magnitude of advancement contribute to the increased incidence of
the patient experiencing post- operative TMJ pain secondary to the
torqueing of the mandible & the TMJ. Distraction osteogenesis
surgery is believed to place minimum of stress on the
temporomandibular joint by virtue of its gradual method of
displacing bone and soft tissue. Less stress on the TMJ is believed
to result in less sequela as a result of the surgery.
3.
Neurosensory factors:
A significant advancement of the mandible in patients of any age is
associated with some degree of neurosensory impairment, either
temporary or permanent. As patients increase in age, the degree of
impairment with this surgery increases accordingly. Distraction
osteogenesis is believed (and thus far I have noted it to be true)
to result in far less neurosensory deficit in patients. This may be
because of the slow displacement of tissue and/or the nerve’s
ability to recuperate after each activation experience.
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Useful Links
http://www.oc-j.com/june01/Distraction.htm
http://www.distraction.net/pages/chapter1.html
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