Transcript Document

DISTRACTION OSTEOGENESIS
AND ITS RELEVANCE IN
CONTEMPORARY PRACTICE OF
ORAL /MAXILLOFACIAL SURGERY
SEMINER PRESENTATION IN
ORAL /MAXILLOFACIAL
SURGERY DEPT
BY
DR ONAIWU I.M
Outline
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Introduction/Definition.
History of Distraction Osteogenesis.
Aims and objectives
Indications
Contraindications
Histology/Pathophysiology
Surgical Procedures
Advantages/disadvantages
Causes of failure
Criteria for success
Conclusion
Introduction
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Distraction Osteogenesis is a slow application of force
to a surgically disrupted bone thereby widening the
gap and resulting in introduction of new bone as well
as soft tissues. In the 1960’s and 1970’s many
surgeons stressed the importance of bone grafting
technique and extensive osteotomies to address this
difficult scenario; research concentrated on methods
of bone grafting to achieve good long term results
but today we know that bone can regenerate itself
without the use of bone grafts or bone growth
promoting factors but by the mode of distraction.
Hence, the concept of Distraction Osteogenesis.
Definition
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Distraction Osteogenesis (DO) also
called callostasis can be defined as
the process of generating new
bone by the slow stretching of
callus in the gap between two bone
segments in response to the
application of graduated tensile
stress across the bone gap.
History of Distraction of
Osteogenesis
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The technique of bone lengthening by
DO was first described in 1905 by
Codivilla, when he reported lengthening
of a Femur by axial distraction forces.
The first trail of distraction
Osteogenesis on human mandible in
unilateral micrognathia and asymmetry
of the face was reported by Alexander
A. Limberg in 1928.
CON’TD
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The technique remained undeveloped until
DR. Gavriel A. Ilizarov, a Russian physician,
further developed the technique in 1950’s.
His patients initially were fractures and nonunions. He utilized a primitive external ring
fixator to compress the injured ends. By
chance a patient reversed the compression
rods, thereby distracting the bone fragments.
Ilizarov’s observed new bone formation
radiographically and pursued this new
method both experimentally and clinically.
CONT’D
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Later he developed the techniques of bone
transportation and limb lengthening.
Based on Ilizarov’s reports, numerous
studies have been conducted to extend the
application of this technique for facial bone
deformities.
Syndel et al in 1972 – to lengthen the
mandible.
Michieli and miotti in Italy in 1977
Karp in 1990 e.t.c
Aims and objectives
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To lengthen the mandible (Unifocal treatment).
To advance the maxilla/midface.
Bone segment transportation (Bifocal distraction
treatment).
Trifocal distraction treatment.
Distraction for Alveolar Augmentation procedures.
Distraction implantology.
To allow multidimentional modelling of the
regenerated bone.
To reduce cost effect of craniofacial surgery
Indications
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Mandibular Distraction Osteogenesis.
Maxillary Distraction Osteogenesis.
Mid facial and/or cranial Distraction
Osteogenesis.
Simultaneous mandibular and maxillary
Distraction Osteogenesis.
Distraction implants.
Mandibular DO
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Hemifacial microsomia
Teacher – Collins Syndrome.
Congenital micrognathia
Pierre Robins Syndrome.
Retrognathia/facial cleft
Craniofacial microsomia
Segmented bone defect (Trauma/pathological disease)
Transverse discrepancies
Alveolar Augmentation
Hypoplasia due to trauma or TMJ ankylosis
Obstructive sleep apnoea
MAXILLARY DO
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Orofacial Clefts
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Unilateral cleft lip and palate
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Bilateral cleft lip and palate
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Undefined cleft
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Unilateral cleft palate
Cleidocranial dysostosis
Maxillary atrophy
Alveolar Augmentation
Midfacial and/or cranial DO
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. cranial synostosis
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crouson’s syndrome
apert syndrome
undefined craniosynostosis
unilateral coronal synostosis
saggittal synostosis
carpenter’s syndrome
midfacial cleft
severe midface atrophy
Simulteneous mand/max DO
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Hemifacial microsomia
Teacher’s Collins synd
Distraction Implants
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Alveolar Atrophy
Contraindications of DO
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Insufficient quantity or quality of bone which inhibit
fixation of the device such as in osteoporosis
Inability to comply with the post operative
distraction regimen and follow up schedule
Metal Allergies
Infections
Certain neuropsychotic disorder e.g. Epilepsy
Immunosuppression
Compromised medical condition
HISTOLOGY
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In the latency period, haematoma formation
begins following osteotomy
The gap between cut ends is composed of
fibroblast & collagen within a matrix of
undifferentiated cells
Early bone formation is as a result of
trabecullae of bone which extend from bony
ends. Bone matrix is lay down by activation of
osteoblast.
Remodeling takes place with bone apposition
& resorption. Osteoclast increases in number.
Pathophysiology
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Distraction Osteogenesis is based
on the tension-stress theory of
Ilizarov which states that slow
steady traction of tissues causes
them to be metabolically active,
resulting in increase in their
proliferating and biosynthetic
functions (histogenesis)
CONT’D
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The mechanical forces are directed
predominantly away from the site of the
surgically disrupted bone.
Distraction Osteogenesis takes place by
intramembranous ossification by
induction of the native tissue. The
newly formed bone between the
distracted ends will result in a stable
lengthening.
SURGICAL PROCEDURES
Clinical protocols
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Patient selection
The decision to use Distraction Osteogenesis should be
based on the following criteria:
Age of patient (paediatric, adolescent and adult
patient)
Severity of the anatomical malformation which can
affect the soft tissue and bony skeleton to a varying
degree.
Potential for bone growth depending on the etiology.
Functional and aesthetic effects
Secondary malformations
Psychological considerations.
Treatment Phase
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Presurgical, operative, latency, distraction,
consolidation, orthodontic phases.
Presurgical phase
This involves:
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Clinical examination
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Clinical photographs
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Study models
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Model analysis
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Preparation of templates
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Biochemical investigations
Radiographic investigations
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OPG
PA mandible
True lateral cephalogram
computerized Tomography (plain,
contrast and 3-D images)
prediction Tracings
Other investigations
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selection of Distraction vector
Selection of Distraction device
OPERATIVE PHASE
This involves osteotomy and
placement of device
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Osteotomy
This involves surgical separation of
bony fragments. Osteotomy is performed
using a small reciprocating saw or a
fissure bur depending on the type of
device you want to fix.
Osteotomy is 90% completed before
the device is applied, then the osteotomy
is completed.
Cont’d
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LATENCY PHASE
This is the initial healing phase
before application of distraction force.
i.e. for callus formation. This varies
from 3 – 7 days.
Cont’d
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DISTRACTION PHASE
Pulling of bone segments apart via
activation of distraction device.
RATE OF DISTRACTION
This can be defined as the number
of millimeters per day at which the
bones surfaces are stretched. The rate
of 1mm a day is considered optimal.
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ORIENTATION OF THE DEVICE
For optimal osteogenesis, recent reports
recommend orienting the distraction device parallel
to the desired direction of distraction this they say is
known to produce tensile strains as compared to
compression, this provides the most favourable
conditions for osteogenesis.
RHYTHM OF DISTRACTION
It can be defined as the number of distractions
per day usually in equally divided increments to total
the rate.
The rhythm may vary from one cycle per day of
1mm to 0.25mm four times per day or 0.5mm twice
daily
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DISTRACTION DEVICE
Distraction devices can be classified as:
Extraoral distraction devices
Intraoral distraction devices
SELECTION OF DISTRACTION DEVICE
It is dependable on the following factors
Type of skeletal deficiency
Desired vector of Distraction
Compliance of the patient
Availability
Cost factor
SELECTION OF DISTRACTION
DEVICE
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It is dependable on the following
factors
Type of skeletal deficiency
Desired vector of Distraction
Compliance of the patient
Availability
Cost factor
DEVICE REQUIREMENTS
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Any device should allow for:
Transfer of distraction forces directly to the desired bone ends.
Provide for adequate rigidity until osseus consolidation occurs.
Examples of Extraoral distractor devices
 Monodirectional appliances
 Bidirectional appliances
 Multidirectional appliances
These extraoral appliances are attached by precutaneous pins to
the bones. These pins are then attached to fixations clamps.
These fixation clamps are in turn connected by a linear
distraction bar which when activated pushes the clamps and the
corresponding bone segments apart.
DISADVANTAGES OF
EXTRAORAL DISTRACTION
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Pin loosening
Pin tract infection
External scars
Hypertrophic scars
Damage to facial nerve
Damage to tooth buds
Non-compliance of patients
Breakage of appliance
INTRAORAL DEVICES
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Examples include
Bone – bone borne
Tooth – bone borne
Implant – tooth hybrid devices
Implant – implant hybrid devices
Extra – mucosal
Internal buried devices
ADVANTAGES OF IO -DO
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No external scars
Simple application
Simple activation
Good patient compliance
No damage to facial nerve
Near total concealment of the devices
Superior psychological tolerance by the patient
Does not limit patients activity level.
DISADVANTAGES
Does not allow multidimentional lengthening
A second surgery is required for removal
CONSOLIDATION PHASE
This may be defined as the number of
days or months from the operation
when the distraction device can be
removed and the bone can be exposed
to unprotected load bearing forces. This
period generally ranges from 6 – 10
weeks. This allow for adequate
consolidation and maturation of the
callus. New bone formation can be
monitored with serial radiographs or CT
scan
Orthodontic phase
Involves orthodontic mgt of the
distorted occlusion after DO
Usually 3-6 months after consolidation
phase.
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Post operative period
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3-7days post op; maintain fixation
Start activation 0.5mm twice daily(1mm per day for
adult and1.5mm per day for px <6yrs)
Check occlusion, oral commissure, progress of
distraction.
Maintain device in place about 8 wks
Long term follow up
Overcorrection in children is preferable
ADVANTAGES OF
DISTRACTION
OSTEOGENESIS
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Relatively simple operative technique, involving bone lengthening and
soft tissue
Good long term stability
Potential for growth in children
Avoidance of bone grafts
Expanded bone is of high quality
Can be performed as early as 2 yrs of age.
Enables surgeon to have post operative control
Shortens hospital stay
Feasible to distract bone graft or irradiated bone
Results are apparent early
Reduced likelihood of relapse
Multi dimensional distraction
Cost effective
DISADVANTAGES
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Skin scars with extraoral devices
Damage to facial nerve
Damage to inferior alveolar nerve
Damage to tooth gem
Premature consolidation especially in children
Transient changes in TMJ
Infection
Non-union/inadequate bone formation
Device failure.
CAUSES OF FAILURE OF
DISTRACTION
OSTEOGENESIS
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Ischaemic Fibrogenesis:
Due to inadequate local blood supply during distraction.
Fibrous tissue forms in the distraction gap, bone columns do
not form from the avascular lost bone surfaces.
Cystic Degeneration:
Occurs when there is blockage of venous outflow from the
system.
Fibrocartilage Non-Union:
Occurs with an unstable external fixation where
microfractures, haemorrhage and cartilage interposition
occurs
Buckling or Bending of the Regenerated bone:
Occurs when the fixation device is unstable or removed
prematurely.
Criteria for success of craniofacial
Distraction Osteogenesis
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Planned distraction distance is obtained
Planned distraction vector is obtained
No pseudoarthrosis
No nerve injury
No tooth damage
No persistent pain, discomfort or infection
No dentoalveolar compensation.
Occlusal balance and adequate function
Patient satisfaction with aesthetic and psychological outcome
Skeletal stability 1 year after the end of the contention period
CONCLUSION
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From the foregoing it is obvious that
the relevance of DO in modern day
oral/maxillofacial surgery and its
reliability in bone augmentation in
clinical practice cannot be
overemphasized.
THANK YOU.