This document discusses distraction osteogenesis, a technique where new bone is formed between vascular bone surfaces that are gradually pulled apart. It involves three phases: a latency period, distraction period where the bone surfaces are distracted 1mm per day, and consolidation period. Histologically, a fibrous interzone forms between the bone surfaces that takes on the role of a growth plate, with intramembranous ossification forming new bone columns across the gap. Key factors for successful new bone formation include stability of fixation, atraumatic corticotomy, and appropriate distraction rate and rhythm.
Distraction osteogenesis is a method of producing unlimited quantities of living bone directly from a special osteotomy by controlled mechanical distraction. The new bone spontaneously bridges the gap and rapidly remodels to a normal macrostructure for the local bone.
Deformity: It’s the position of a limb/Joint, from which it cannot be brought back to its normal anatomical position.
Described as abnormalities of :
Length
Angulation
Rotation
Translation
Combination
Distraction osteogenesis is a method of producing unlimited quantities of living bone directly from a special osteotomy by controlled mechanical distraction. The new bone spontaneously bridges the gap and rapidly remodels to a normal macrostructure for the local bone.
Deformity: It’s the position of a limb/Joint, from which it cannot be brought back to its normal anatomical position.
Described as abnormalities of :
Length
Angulation
Rotation
Translation
Combination
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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
= Definition
= Historical development of craniofacial distraction.
= Distraction device classification.
= Biological aspect of osteogensis distraction.
= Distraction histogensis:
Effect on muscle
Effect on the peripheral nerves.
Effect on TMJ.
Effect on periodontal ligamment.
Effect on gingival tissues.
= Biomechanical effect of distraction device orientation during mandibular lengthening and widening:
In transverse plane
In Sagittal plane
What is fixation?
Fixation in orthopedics is the process by which an injury is rendered immobile. This may be accomplished by internal fixation, or by external fixation.
What is internal fixation?
Internal fixation is an operation in orthopedics that involves the surgical implementation of implants for the purpose of repairing a bone
What is osteosynthesis?
Osteosynthesis is the reduction and internal fixation of a bone fracture with implantable devices that are usually made of metal. It is a surgical procedure with an open or per cutaneous approach to the fractured bone. Osteosynthesis aims to bring the fractured bone ends together and immobilize the fracture site while healing takes place. In a fracture that is rigidly immobilized the fracture heals by the process of intramembranous ossification
INDICATIONS for internal fixation
History of Fracture Treatment and Development Of Modern Osteosynthesis
In the Preantibiotic era, closed reduction of fractures was understandably the rule for most fractures. However, when closed reduction was insufficient, external fixation appliances served to maintain skeletal units in position, frequently without the need for MMF (Maxillo-mandibular fixation) .Following the development of antibiotics, the open treatment of fractures began to be used on a more frequent basis.
Rigid internal fixation (RIF) is “Any form of fixation applied directly to the bones which is strong enough to permit active use of the skeletal structure during the healing phase and also helps in healing”.
Bone fractures have been treated with various conservative techniques for centuries and it was not until the eighteenth century that internal fixation was first documented.
Icart, a French surgeon in Castres, performed ligature fixation with brass wire on a young man with a humeral fracture.
1886, when Hansmann of Hamburg published a technique using retrievable metal bone plates with transcutaneous screws.
Soon after, a Belgian surgeon, Albin Lambotte, improved these techniques and coined the term internal fixation.
Lambotte developed and manufactured a variety of bone plates and screws and much of his armamentarim remained in use until the 1950s.
In the twentieth century, Sherman improved on Lambotte’s designs and created parallel, threaded, finepitched, self-tapping screws. This hardware was made of corrosion-resistant vanadium steel, which was a strength improvement over silver and ivory fixation materials.
BIOLOGY OF BONE AND BONE HEALING
Bone is a complex and ever-evolving connective tissue and serves multiple purposes. Besides being the main constituent of the human skeletal system, bone is highly metabolically active and essential for the regulation of serum electrolytes—namely, calcium and phosphate.
Marrow cavities are filled with hematopoietic elements necessary to manufacture and maintain blood components and regulate the immune system. Bone is comprised
Fracture Healing,Introduction,Pathology&Stages,Factors influencing osteogenesis,differences in healing of fractured bone by conservative&operative management.
2. Mechanical induction of new bone that occurs between
vascular bony surfaces that are gradually pulled apart by
gradual distraction.
New bone formed bridges the gap & remodels to normal
bone macrostructure.
Tension stress effect on growth & genesis of tissues.
3. Developed by Ilizarov in 1956
Highly modular fixators allow formation of new bone in
almost any plane as D.O follows the vector of applied force.
Age: as long as Pt had # healing potential.
INDICATION: bone grafting, LLD, nonunion, deformity,
bone defects 2* to trauma, infection, tumor.
4. Advantages over bone grafting
Reduces donor site morbidity
Autograft is limited
No fear of transmission of antigens, bacteria, viruses, dead
foreign bodies.
In infected wounds.
Risk of # in B.G over extended period of time
B.G will never incorporate in to living B.
5. Components of D.O
Application of ext.fix – stability, applies forces
Corticotomy
Postop period
1. Latency period
2. Distraction P.
3. Consolidation P.
6. DEFINITION
CORTICOTOMY: low energy osteotomy, performed using an
osteotome to cut only the cortical surface thus preserving the
medullary canal, nutrient vessel, endosteum, periosteum
LATENCY PERIOD: Initial healing response is allowed to
bridge the cut surfaces before distraction is initiated.
7. Rate: no of millimeter that the bone surfaces are pulled apart
each day.
Rhythm: no of distractions per day
Healing index: no of centimeters of N.B divided by no of
months from the surgery to date of full wt bearing.
8. Transformation osteogenesis: conversion of non osseous
tissues such as fibrocartilage in nonunion in to normal bone.
Done through comb compression & distraction forces,
augmented by corticotomy.
Bone transportation: regeneration of intercalary B.D through
corticotomy & distraction & tranf. Osteogenesis.
9. Critical factors for B. formation
Stability of fixation [circular F]
Atraumatic corticotomy.
Rate
Rhythm of distraction.
10. HISTOLOGY
LATENCY P: similar to # healing
DISTRACTION P: mesenchymal cells begin to organize in to
bridge of collagen & immature vascular sinusoids, bridge formed
always parallel to direction of distraction.
I Week Distraction: central zone of relatively avascular fibrous
tissue bridges the 7 mm of C.gap.
FIZ: fibrous interzone [no osteoid/ O.B]
11.
12. II WEEK - Distraction
Clusters of osteoblasts appear on each side of FIZ adj to vascular
sinuses.
Collagen bundles fuse with osteoid like M.
1* bone spicules –enlarge gradually by circumferential
apposition.
Later osteoid began to mineralize the 1*B.S PMF[primary
mineralisation front]
PMF – extend from both corticotomy site, towards the central
FIZ.
13. III Week
Mineralization process continues.
As the gap increases, bridge is formed by elongation of bone
spicules.
Large thin sinusoids surround each micro column of new
bone MCF [micro column formation].
At the end of D., FIZ ossifies & MCF unifies completely
bridging the gap.
15. Physiology
Fibrous interzone assumes the role of growth plate. [pseudo
G.P]
Intramembranous ossification in its purest form. [if stability]
Local & regional blood supply is most important determining
factor.
17. Rate & Rhythm: biosynthetic pathways at cellular levels , protein
synthesis & mitosis.
Macromotion: [shear force] disrupt the delicate bone & vascular
channels
Peripheral vascular disease
Traumatic corticotomy- disturb the local blood flow
Initial diastasis- inhibit the formation of 1* fibrovascular bridge.
18. Indications for increase in R & R
Young Pt [up to 12-14 yrs]
X ray premature consolidation.
X ray uncompleted bone cut at the site of corticotomy.
In any event, increase in distraction speed & rhythm cannot
exceed 2 mm/ day.
19. Indication for reduction
Severe pain at the site of distraction, esp after creating 3-4
cm gap.
Clinical signs of peripheral vascular & neurological
deficiency.
X ray slow development of regeneration
Reduction in D cann’t be less than .25- .50 mm/ day .
20. Ilizarov recommended that the number of actual distractions
(rhythm of distraction) should be at least four, achieving a
total of 1 mm of total distraction (rate of distraction) in four
divided doses.
constant distraction over a 24-hour period produces a
significant increase in the regenerate quality
21. ASSESSMENT
Corticotomy: check for completeness in C-arm. Distracting
<2 mm, angulation < 10-15*, rotating < 20-30*.
Adequate reduction of corticotomy gap.
Length & alignment of D.G checked weekly or biweekly by
X ray.
N.B mineralization appears by 3rd
wk of D. –fuzzy,
radiodense columns extending from both cut surfaces
22. N.B formation should span entire cross sectional area of host
bone cut surfaces.
N.B appears bulging, FIZ is narrowing distraction should be
accelerated.
N.B shows as hour glass appearance, FIZ widens D. rate
reduced.
23. USG: not regularly used. Cyst formation stop distraction, gap is
gradually closed.
QCT: [Quantitative C.T] measuring the mineralization of
osteogenic area.
Compared with similar region on normal contralateral limb
described as % of normal.
Normally FIZ- 25-35%, PMF- 40-55%, MCF- 60-70%.
24. Triphasic bone scan: both sides of distraction gap should be
hot in all three phases.
If it is cold, stop distraction.
25. consolidation
Plain x rays – monthly basis, condition of the cortex &
medullary canal are noted in the osteogenic area –
orthogonal views
Bone density may appear reduced.
QCT- demonstrates stability.
26. ACCORDION TECH
Monofocal compression- distraction tech for nonunion
treatment.
Alternate compression & distraction maneuver is used 2-3
times to stimulate bone neogenesis.
Local scar tissues are initially crushed to be transformed in to
tissues capable of neogenesis.