Distraction osteogenesis is a biological process used to treat craniofacial deformities. It involves separating bone segments gradually through incremental traction to stimulate new bone formation. Historically, it has been used since the early 1900s to lengthen limbs, and was first applied to the craniofacial skeleton in the 1980s. The process involves osteotomy, latency, distraction, consolidation, and remodeling phases. Both internal and external devices can be used uni-directionally or multi-directionally. Factors like age, site of surgery, rate and rhythm of distraction influence outcomes. The orthodontist plays a key role in planning distraction vectors and post-treatment orthodontics.
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
Rigid internal fixation refers to the direct method of fracture fixation where the hardware or implant used for fixation provides sufficient rigidity for the jawbone to withstand masticatory stresses.
Avoids immobilization by MMF
Does not allow micromotion of fracture segments
Goals of AO/ASIF technique for rigid fixation
Anatomic reduction of bone fragments
Functionally stable fixation of the fragments
Preserving the blood supply to the fragments by atraumatic surgical procedures
Early, active and pain free mobilisation
Compression osteosynthesis
Based on AO/ASIF principles
These plates included pear-shaped holes at the extreme ends
Dynamic compression plate
Produce compression between bone fragments on activation
300kPa/cm2
Indication
Nonoblique fracture with good bony apposition after reduction
Contraindications
Severely oblique fracture
Comminuted fracture
Fracture with bone loss
Properties of plate
Plate has inclined plane in the hole proximal to the fracture
The highest portion of the inclined plane lies on the outer aspect
2 types of screws- compression screw and static screw
Min two screws on each side
Unfavourable fracture requires longer plates with more screws
Order of fixation
Plate bending
Bicortical screws are used
Fixation protocol
Disadvantages
Require precise adaptation
If used on oblique fractures, the fragments slide over one another
Maladapted plate in anterior mandiblecreates widening of mandible
Technique sensitive
Ideally should be placed on tension zone, but due to anatomic reasons the plate is placed on the inferior border
In fracture with good reduction and no bone loss, causes stripping of screws and bone splintering adjacent to fracture
Eccentric dynamic compression plate
Used in situations where tension band application is not possible
Presence of impacted 8 with angle fracture
Edentulous mandibular fracture
Avulsion of bone from fracture site
Plate design
Advantage
Even distribution of forces along length of fracture
Disadvantage
Technique sensitive
Results not superior to other fixation methods
Lag screw
Oblique fracture in long bones
Principle- a screw that glides through the cortex of one fragment and engages the cortex of the opposite fragment with its thread, draws the fragments together and compresses them when tightened. Gliding holes and thread holes must be coaxial
- (Pics)
Fixation osteosynthesis
This includes
Reconstruction plate
THORP
Locking plate
Indications
Oblique fracture
Comminuted fracture
Loss of bone fragments in fracture
Questionable post op compliance
Non atrophic edentulous fracture
Reconstr
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
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
Rigid internal fixation refers to the direct method of fracture fixation where the hardware or implant used for fixation provides sufficient rigidity for the jawbone to withstand masticatory stresses.
Avoids immobilization by MMF
Does not allow micromotion of fracture segments
Goals of AO/ASIF technique for rigid fixation
Anatomic reduction of bone fragments
Functionally stable fixation of the fragments
Preserving the blood supply to the fragments by atraumatic surgical procedures
Early, active and pain free mobilisation
Compression osteosynthesis
Based on AO/ASIF principles
These plates included pear-shaped holes at the extreme ends
Dynamic compression plate
Produce compression between bone fragments on activation
300kPa/cm2
Indication
Nonoblique fracture with good bony apposition after reduction
Contraindications
Severely oblique fracture
Comminuted fracture
Fracture with bone loss
Properties of plate
Plate has inclined plane in the hole proximal to the fracture
The highest portion of the inclined plane lies on the outer aspect
2 types of screws- compression screw and static screw
Min two screws on each side
Unfavourable fracture requires longer plates with more screws
Order of fixation
Plate bending
Bicortical screws are used
Fixation protocol
Disadvantages
Require precise adaptation
If used on oblique fractures, the fragments slide over one another
Maladapted plate in anterior mandiblecreates widening of mandible
Technique sensitive
Ideally should be placed on tension zone, but due to anatomic reasons the plate is placed on the inferior border
In fracture with good reduction and no bone loss, causes stripping of screws and bone splintering adjacent to fracture
Eccentric dynamic compression plate
Used in situations where tension band application is not possible
Presence of impacted 8 with angle fracture
Edentulous mandibular fracture
Avulsion of bone from fracture site
Plate design
Advantage
Even distribution of forces along length of fracture
Disadvantage
Technique sensitive
Results not superior to other fixation methods
Lag screw
Oblique fracture in long bones
Principle- a screw that glides through the cortex of one fragment and engages the cortex of the opposite fragment with its thread, draws the fragments together and compresses them when tightened. Gliding holes and thread holes must be coaxial
- (Pics)
Fixation osteosynthesis
This includes
Reconstruction plate
THORP
Locking plate
Indications
Oblique fracture
Comminuted fracture
Loss of bone fragments in fracture
Questionable post op compliance
Non atrophic edentulous fracture
Reconstr
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
Fracture of Mandible, 2003
Copyright by Department of Oral & Maxillofacial Surgery
University of Dental Medicine, Myanmar
Feel free to request to take it down this slide if you are copyright owner.
Distraction osteogenesis in orthodontics -Dr.G V SHETTYDr.G.V SHETTY
DISTRACTION IN ORTHODONTICS IMPLICATIONS
ROLE OF ORTHODONTIST IN MANAGEMENT OF SEVERE MAXILLOMANDIBULAR OR OROFACIAL DISCREPANCY
SCOPE OF DISTRACTION OSTEOGENESIS
Fracture of Mandible, 2003
Copyright by Department of Oral & Maxillofacial Surgery
University of Dental Medicine, Myanmar
Feel free to request to take it down this slide if you are copyright owner.
Distraction osteogenesis in orthodontics -Dr.G V SHETTYDr.G.V SHETTY
DISTRACTION IN ORTHODONTICS IMPLICATIONS
ROLE OF ORTHODONTIST IN MANAGEMENT OF SEVERE MAXILLOMANDIBULAR OR OROFACIAL DISCREPANCY
SCOPE OF DISTRACTION OSTEOGENESIS
Sinus lift with dental implants Placement.(with Clinical Photographs) Dr. ...All Good Things
Hi. This is Dr. Amit T. Suryawanshi. Oral & Maxillofacial surgeon from Pune, India. I am here on slideshare.com to share some of my own presentations presented at various levels in the field of OMFS. Hope this would somehow be helpful to you making your presentations. All the best & your replies are welcomed!
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
ABDOMINAL TRAUMA in pediatrics part one.drhasanrajab
Abdominal trauma in pediatrics refers to injuries or damage to the abdominal organs in children. It can occur due to various causes such as falls, motor vehicle accidents, sports-related injuries, and physical abuse. Children are more vulnerable to abdominal trauma due to their unique anatomical and physiological characteristics. Signs and symptoms include abdominal pain, tenderness, distension, vomiting, and signs of shock. Diagnosis involves physical examination, imaging studies, and laboratory tests. Management depends on the severity and may involve conservative treatment or surgical intervention. Prevention is crucial in reducing the incidence of abdominal trauma in children.
Local Advanced Lung Cancer: Artificial Intelligence, Synergetics, Complex Sys...Oleg Kshivets
Overall life span (LS) was 1671.7±1721.6 days and cumulative 5YS reached 62.4%, 10 years – 50.4%, 20 years – 44.6%. 94 LCP lived more than 5 years without cancer (LS=2958.6±1723.6 days), 22 – more than 10 years (LS=5571±1841.8 days). 67 LCP died because of LC (LS=471.9±344 days). AT significantly improved 5YS (68% vs. 53.7%) (P=0.028 by log-rank test). Cox modeling displayed that 5YS of LCP significantly depended on: N0-N12, T3-4, blood cell circuit, cell ratio factors (ratio between cancer cells-CC and blood cells subpopulations), LC cell dynamics, recalcification time, heparin tolerance, prothrombin index, protein, AT, procedure type (P=0.000-0.031). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and N0-12 (rank=1), thrombocytes/CC (rank=2), segmented neutrophils/CC (3), eosinophils/CC (4), erythrocytes/CC (5), healthy cells/CC (6), lymphocytes/CC (7), stick neutrophils/CC (8), leucocytes/CC (9), monocytes/CC (10). Correct prediction of 5YS was 100% by neural networks computing (error=0.000; area under ROC curve=1.0).
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
share - Lions, tigers, AI and health misinformation, oh my!.pptxTina Purnat
• Pitfalls and pivots needed to use AI effectively in public health
• Evidence-based strategies to address health misinformation effectively
• Building trust with communities online and offline
• Equipping health professionals to address questions, concerns and health misinformation
• Assessing risk and mitigating harm from adverse health narratives in communities, health workforce and health system
DISSERTATION on NEW DRUG DISCOVERY AND DEVELOPMENT STAGES OF DRUG DISCOVERYNEHA GUPTA
The process of drug discovery and development is a complex and multi-step endeavor aimed at bringing new pharmaceutical drugs to market. It begins with identifying and validating a biological target, such as a protein, gene, or RNA, that is associated with a disease. This step involves understanding the target's role in the disease and confirming that modulating it can have therapeutic effects. The next stage, hit identification, employs high-throughput screening (HTS) and other methods to find compounds that interact with the target. Computational techniques may also be used to identify potential hits from large compound libraries.
Following hit identification, the hits are optimized to improve their efficacy, selectivity, and pharmacokinetic properties, resulting in lead compounds. These leads undergo further refinement to enhance their potency, reduce toxicity, and improve drug-like characteristics, creating drug candidates suitable for preclinical testing. In the preclinical development phase, drug candidates are tested in vitro (in cell cultures) and in vivo (in animal models) to evaluate their safety, efficacy, pharmacokinetics, and pharmacodynamics. Toxicology studies are conducted to assess potential risks.
Before clinical trials can begin, an Investigational New Drug (IND) application must be submitted to regulatory authorities. This application includes data from preclinical studies and plans for clinical trials. Clinical development involves human trials in three phases: Phase I tests the drug's safety and dosage in a small group of healthy volunteers, Phase II assesses the drug's efficacy and side effects in a larger group of patients with the target disease, and Phase III confirms the drug's efficacy and monitors adverse reactions in a large population, often compared to existing treatments.
After successful clinical trials, a New Drug Application (NDA) is submitted to regulatory authorities for approval, including all data from preclinical and clinical studies, as well as proposed labeling and manufacturing information. Regulatory authorities then review the NDA to ensure the drug is safe, effective, and of high quality, potentially requiring additional studies. Finally, after a drug is approved and marketed, it undergoes post-marketing surveillance, which includes continuous monitoring for long-term safety and effectiveness, pharmacovigilance, and reporting of any adverse effects.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
4. Distraction Osteogenesis
“A biological process of new bone formation between
the surfaces of osteotomized bone segments that are
separated gradually by incremental traction”
Distraction Histogenesis :
– Adaptive regenerative changes in surrounding soft
tissues
5. Historical Overview
Alessandro Codiwilla (1905)
– First report of surgical limb lengthening
– Oblique osteotomy and external traction pins
– Complications: infections, overstretching, poor blood
supply, and inadequate fixation
6. Historical Overview
G.A. Ilizarov (1950’s)
– Lengthening limbs through gradual distraction of
fracture callus
– Rhythm and rate of distraction
– Minimal complications
7. Historical Overview
Mc’Carthy– (1989) conducted the first reported human
trial of craniofacial distraction using external fixators.
4children with craniofacial anomalies were subjected to a
distraction protocol of upto three weeks followed by a
8-10 week consolidation.
Long-term studies of the same patients indicate a
successful result.
8. Historical Overview
• MOLINA and ORTIZ MONASTERIO(1995) used
bi-directional appliances
• Mc’CARTHY demonstrated the efficacy of a
mulitdirectional appliance.
• GUERRERO (1990) used an intra-oral appliance
to widen mandibular arches.
8
11. Historical Overview
Chin and Toth (1996)
• Mandibular alveolar distraction osteogenesis to increase the
height of the alveolus
Chin M, Toth BA. Distraction osteogenesis in maxillofacial surgery using internal devices:
review of five cases. J Oral Maxillofac Surg. 1996 Jan;54(1):45-53.
13. Types of Distraction Osteogenesis
• Defined on the number of foci at which osteogenesis
occurs:
– Monofocal elongation DO
– Bifocal distraction
– Trifocal distraction
13
15. Osteotomy Phase
• Divides the bone into two segments
• Triggers process of bone repair
– Angiogenesis
– Fibrogenesis
– Osteogenesis
16. Latency Phase
• Period from bone division to onset of distraction
• Inflammation and soft callus formation of the fractured bone
• Soft callus formation begins 3-7 days and lasts 2-3 weeks
• Latency period = 5-7 days
17. Distraction Phase
• Characterized by the application of traction forces to
osteotomized segments
• Rate : 1 mm/day
• Rhythm : 0.25 mm every 6 hours
0.5 mm twice a day
• Duration : 1-3 weeks
18. Consolidation Phase
Cessation of traction forces to removal of distractor
• Newly formed bone mineralizes and increases in bone density
and strength
Duration: 3- 4 months
19. Remodeling Phase
• Removal of distractor to application of functional
loading
• Formation of lamellar bone
20. Indications
• Congenital retrognathic syndromes
• Severe mandibular deficiency > 10-15 mm
• A short mandibular ramus
• TMJ degenerative disease
• Obstructive sleep apnea
• A narrow, V-shape mandible
• Maxillary deficiency in CLP or Craniosynostosis
• Post-traumatic growth disturbance
• Atrophy of edentulous segments
• Oncologic mandibular osseous defects
21. Advantages
• Safe and effective surgical technique can be
performed on outpatient basis
• Can be done in children as young as 2 years
• Distraction histogensis results in growth of
associated functional matrix
• Long term improvement in condylar morphology
• Greater degree of correction can be achieved
• Grafts are not required
• Minimal skeletal relapse
21
22. Disdvantages
• Requires second surgery to remove distractor
appliances
• Risk of infection at surgical site is greater
• Pain and discomfort during distraction
• Required meticulous planning
• Results are not as precise as orthognathic surgery
22
26. • FACTORS AFFECTING DO
• BIOLOGIC FACTORS
• AGE
• SITE OF SURGERY
• LATENCY PERIOD
• RATE AND RYTHM
26
27. • BIOLOGIC FACTORS
• Increased micromotion by increasing rhythm causes
increased vasculogenesis and enzymes and decreases the
tissue damage and the degenerative changes
• CONSOLIDATION PHASE
• Assessment of new bone is by:
• I. Plain radiography
• ii. Quantitaive Computed Tomography (QCT)
• iii. Ultrasonography
• iv. Dual energy X-ray absorptimetry
27
28. • BIOMECHANICAL FACTORS
• Planning the distraction vector
• Device fixity
• Need for ‘ Bone moulding’
28
PLANNING THE DISTRACTION VECTOR
VERTICAL HORIZONTAL OBLIQUE
29. Factors Affecting DO
Local Factors Systemic Factors Distraction Factors
Osteoprogenitor Supply Age Rate of Distraction
Blood Supply Metabolic Disorders Frequency of
Distraction
Infection Vitamin D Deficiency Latency Period
Soft Tissue Scarring Connective Tissue
Disease
Rigidity of Fixation
Bone Stock Steroid Therapy Consolidation Period
Prior Radiation Therapy Calcium Deficiency Length of Regenerate
29
Imola MJ, Ducic Y, Adelson RT. The secondary correction of posttraumatic craniofacial
deformities. Otolaryngol Head Neck Surg. 2008;39(5):654-60.
30. Biomechanical Considerations
• Factors related to distractor device
• Factors related to bone and surrounding tissues
• Factors related to device orientation
31. Properties of Distractor
• Mechanical integrity of device
• Number, length and diameter of fixation pins
• Material properties
32. Quality of Hard and Soft Tissues
• Shape of the bone
• Cross-sectional area
• Density of bone
• Tension of soft tissues
• Site of osteotomy and joint function
35. Distractor Orientation
• Transverse plane (Model III & IV)
– Distractors placed parallel to lateral surface of
mandible (III), parallel to each other (IV)
38. External Unidirectional
Distractors
• Single calibrated rod with two clamps
• Each clamp holds two 2-mm half-pins
• 20-24mm of bone posterior to last tooth bud
• Limitations:
– Difficulty in predicting direction
– Inability to change direction
– Scarring
39. External Bidirectional Distractors
Molina and Ortiz Monasterio
• Two geared arms 5 cm in length
• Middle screw - change angulation
• Double osteotomy (horizontal in ramus and vertical in corpus)
• Two 2-mm pins in each segment of bone
40. External Bidirectional Distractors
Advantages:
– Additional degree of freedom
– Deficiencies in more than one plane
– Two osteotomies - flexible distraction
– Easy and optimal device placement
Potential problems
– Risk for avascular necrosis of intervening segment
– Damage to tooth buds during pin placement
41. External Multiplanar Distractors
• Two distraction rods with sliding clamps connected
in by multiplanar hinge in the middle
• Two arms extend with pin clamps at either end
• Each quarter turn results in 0.25 mm of expansion
42. Use of Intermaxillary Elastics
• Modification of distraction vectors
• Intermaxillary elastics can have skeletal effects
during distraction
– Secondary to molding of the regenerate
• “Fine tuning” of the occlusal outcome
• Elastics may be worn in Class II, III, vertical, or
transverse pattern
• Helpful in the retention of results
42
43. Mandibular Extra-oral
Distraction Devices
Advantages
• Small children applicability
• Simplicity of attachment
• Ease of manipulation
• Multiplanar adjustment
• Low infection rate
• Out patient surgery
Disadvantages
• Apprehension
• Bulky appliance
• Social inconvenience
• Facial scars
• Reduced consolidation
period
44. Internal Distractors
Advantages
Eliminate the problems of:
– Facial scarring
– Pin tract infections
• Better esthetics
• Long consolidation
period possible
Disadvantages
– Unidirectional distraction
– Difficult activation of
ramus distractors
– Poor fit
– Trauma to surrounding
tissues
45. Internal Tooth-Borne Distractor
Device
• Preformed stainless steel crowns
• Distractor fabricated on cast, crowns cemented
• An osteotomy made between selected teeth,
distractor placed
• Latency period: 3-4 days
• Consolidation period 5 weeks
46. Symphesial Distraction
• For V shape mandible
• Severe mandibular crowding
• Brodie’s syndrome
• To avoid inderdental stripping or extractions
46
49. Symphesial Distraction
Samchukov et al. (1998) reported 0.34-degree condylar
rotation for every 1 mm of widening
49
Samchukov, M.L., Cope, J.B. Cherkashin A.M., (2001) The biomechanical effects of distraction device
orientation during mandibular lengthening and widening. In: Samchukov, M.L., Cope, J.B.,
Cherkashin, A.M. (Eds.), Craniofacial distraction Osteogenesis. Mosby, St. Louis, pp. 131–146.
52. 52
DISTRACTION OSTEOGENESIS
The Orthodontist’s role
a. Decompensation of the dentition
b. Planning the distraction vector
c. Bone Moulding using intermaxillary
elastics
d. Post-distraction Orthodontics
53. • Currently Unresolved issues
a.Effects of distraction on growth
b.Limits of distraction osteogenesis
c. Effects of distraction on eruption and
movement of teeth.
d.Long term stability of regenerate bone.
53
54. • Directions for the future
a.Refinements in the distraction protocol
b.Improvement in distraction devices
c. Enhancement of regenerate maturation
54
Distraction histogenesis: A traction force applied to bony segments also creates tension in the surrounding soft tissues, initiating a sequence of adaptive changes termed as distraction hisogenesis
Bone lengthening by distraction osteogenesis dates back to Alessandro Codiwilla, who in 1905 published the first report of surgical limb lengthening. He used an oblique osteotomy and external traction pins to lengthen limbs which were originally shortened by congenital deformity or trauma. The basic method of externally distracting a surgically-created osteotomy did not change much for the next 70 years. During the first half of the century, this technique did not gain clinical acceptance because every surgeon attempting leg lengthening procedures encountered serious complications such as infections, overstretching, poor blood supply, and inadequate fixation.
In 1950’s, Illizarov, a Russian orthopedic surgeon defined a number of biological and mechanical factors that play a role in the process of new bone formation and began the modern era of DO, applying it primarily to lengthen limbs.
He gave the law of tension stress that if steady traction is applied to bone fragments after corticotomy or osteotomy, the bone can be lengthened by formation of new bone at the surgical site by callotosis.
In particular, he explained the significance of rhythm and rate of distraction, preservation of the periosteum, bone marrow and vascularity, and stable fixation to successful bone lengthening with minimal complications.
McCarthy was the first who introduced the application of craniofacial distraction in mandible
Maxillary distraction was reported in 1993 by Rachmiel et al who performed midface gradual advancment on five sheep. Block et al demonstrated anterior maxillary advancement using tooth borne device in Dog
Polley et al used an externally fixed cranial halo frame to distract the midface
Disraction technique is divided into two categories depending on the anatomic sides. Predominant method of distraction in maxillofacial region is callotasis
The basic technique of DO involves five sequential steps
A corticotomy is made preserving the local blood supply to both the periosteum and medullary canal. However, greater blood supply in the facial skeleton prefer osteotomy of the jaws which is more predictable and less uncomfortable for the patients
The distraction device is inserted so that the two bony ends are stable during the first five days. This period is called the latency period during which initial fracture healing and callus formation occurs.
If distraction begun too early, the result is decreased bone formation often with cartilaginous elements present and decreased mechanical strength of new bone.
If it is too late (after the hard callus formation), the distraction device may be unable to further separate the bone.
There are two important variables in the activation i.e. rate or amount of distraction per day and rhythm that is how frequently the device is activated.
Ideally, Distraction of the bony ends is initiated at a rate of 1 mm/day at a rhythm of 0.25 mm every 6 hours. In majority of maxillofacial cases the most common protocol is 0.5 mm twice a day,
New bone is usually visible in the distraction gap by the third week. Ossification occurs at the edges and then progresses toward the center of the stretched callus.
The distraction device is left in place while the regenerate bone matures and remodels. The distractor must be rigid enough to prevent movement of bone during this period of healing. If movement occurs, either from inadequate fixation or premature removal of the appliance, a malunion or fibrous non union may occur.
Ideally the consolidation period should coincide with the time required for complete mineralization of the bone
Severe deficiencies of either jaw that needs to be ameliorated at an early age such as Pierre robin anomaly
Severe mandibular deficinecy that requires lengtheing of mandible more than 10-15 mm. Growth modification can produe only 5 mm of diffrential growth. Orthognathic surgery becomes more difficult and less predictable when more than 8-10mm of advancement and more than 15 mm is outside of their envelope of surgical movement
A short mandibular ramus that muse be lengthened. With conventional surgery the musculature of pterygomasseteric sling does not adapt to lengthening of ramus. However, distraction histogenesis could be the way to overcome this limitation.
applied at a younger age (2 years) than is typical for
the costochondral rib graft reconstruction It has
obviated the need for autogenous bone grafting, as is
often required in traditional orthognathic surgical
procedures.
Distraction histeogensis result in growth of associated soft tissues, such as the muscles of mastication, subcutaneous tissue, and skin (functional matrix).
The patient should be examined with the head in an upright position, a goal often rendered difficult because of craniofacial asymmetry and head tilt. One should note forehead, orbital, zygomatic, and external ear position and relationships by also viewing the patient from the "bird's eye" and submental vertex positions. In patients with unilateral craniofacial microsomia, the position of the oral commissure should be documented, and the distance between it and the external auditory canal (or ear remnant) recorded.The position and contour of the chin, inferior border, and angle of the mandible are recorded. The external ear is graded according to one of several classification protocols. The intraoral examination documents the status of the occlusion. It is important to relate the intraoral pathology to the extraoral skeletal and soft tissue abnormalities. The occlusal plane or transverse cant should be related to the transorbital plane (Fig 1A), a determination later facilitated by examination of the
posteroanterior cephalogram (Fig 1B). Assessment of
the transmeatal, transgonial, and midsagittal (verti
The clinician must
position the head so that the midsagittal plane is
perpendicular to the floor and the lateral borders of
the orbital rims are symmetrically positioned in relation
to the lateral borders of the calvarium.
The biomechanical parameters of osteodistraction can be divided into several categories
Extrinsic or fixator related factors
Intrinsic or tissue related factors
Factor related to device orientation
These parameters affect the mechanical integrity of the distraction device which in turn influence the stability of the bone fixation
These parameters include number, length and diameter of fixation pins, rigidity of the device and material properties of the distractor mechanism.
Intrinsic parameters affect the quality of the forming distraction regenerate. These parameters include geometric shape, crossectional area, density of distracted bone segments, the length of distraction regenerate and tension of soft tissue envelope.
The effect of distractor device orientation on bilateral mandibular lengthening was evaluated first in transverse plane. Simulated osteotomy of the mandibular corpus was performed posterior to third molars bilaterally. Two linear distractors were placed parallel to the lateral surface of mandible in the Model 1. Note the intercondylar width increased during lengthening compared with predistraction phase. The magnitude of this increase was propotional to the amount of lengthening. Because of the limited lateral movement of condyles, this generate unfavorable reactive forces. Clinically, this will result in bending of distraction device, localized pressure resorption of bone around screws and rotation of proximal segments about the condyles leading to joint compression.
In model II, distractors are placed parallel to the direction of distraction (parallel to each other and to midsagittal axis). No intercondylar width increase developed during lengthening. In this model, the lateral forces and the tensile and compressive strains were minimized significantly
In model III and IV, bilateral mandibular corpus lengthening and midsymphyseal widening occurring simultaneously. A third osteotomy was simulated thorugh the middle of the symphysis and a third distractor was placed on bone segments of the anterior mandible with lengthening distractors placed parallel to the lateral surface of mandible in model III and parallel to the direction of distraction in model IV.
Midline widening results in rotation of the mandibular condyle in both models, however, the intercondylar distance increased during lengthening only in model III. The condylar rotation seen during midline widening, if not compensated can create inappropriate loading on the articular surfaces however, the histological changes were minor and were limited to atypical morphology of one two or three of the layers of the condylar cartilage.
Mandibular corpus lengthening with distractors placed parallel to the inferior border of the mandible (model V). A simulated osteotomy of the mandublar corpus ws performed posterior to the third molars bilaterally, and linear distractors were positioned on the lateral surface of the bone segments. Note the inferior translation of the distal segment resulting in increase in lower anterior facial height during lengthening.
Each mm of distraction generated 0.3mm increase in LAFH when distraction vector angle was 17 degrees
distractor consisted of a single calibrated rod with two clamps. Each clamp holds two 2-mm half-pins that are placed on either side of the osteotomy. Approximately 20 mm to 24 mm of bone stock posterior to the last tooth bud is necessary to place this device.
It was recognized early on that the external linear distractor had several limitations.
The disadvantages included scarring as a result of pins dragging through the skin during expansion, difficulty predicting the direction in which the distraction would proceed, and the inability to change direction once the distraction process had begun. The initial placement of the pins determines the placement of the device and, therefore, the direction of distraction.
Molina and Ortiz Monasterio developed an external bidirectional device in patients with mandibular micrognathia involving both the ramus and corpus and angle of mandible and required independent corrections in two directions.
The device consists of two geared arms 5 cm in length connected to a middle screw that enables the arms to be moved up or down to change angulation. For adequate correction of mandibular deformities, two distraction sites were generated via double level corticotomy which enabled lengthening in both parts of the mandible simultaneously but independently
A bidirectional distraction appliance provides an additional degree of freedom over the unidirectional device. More severe mandibular hypoplasias, such as Treacher Collins syndrome and bilateral micrognathia, involve deficiencies in more than one plane. In the case of Treacher Collins syndrome, bidirectional distraction is essential for correction of the two-step occlusal plane and ramus deficiency.
When two osteotomies are performed, distraction can be performed on both arms of the distractor, and expansion proceeds at twice the rate of a unidirectional device.
A criticism of the double osteotomy procedure is the risk for avascular necrosis of the intervening segment and damage to tooth buds during pin placement. Pretreatment planning should address these potential problems.
The ability to make transverse changes was the final step in achieving three-dimensional control. The hypoplastic mandible is not only deficient in ramus height and body length, but the affected ramus may lie in a more medial position, resulting in a decreased bigonial distance.
The multiplanar device consists of two distraction rods with gradually sliding clamps connected in the middle by universal multiplanar hinge. Two arms extend from the housing with pin clamps at either end. Each quarter turn of the wheel results in 0.25 mm of expansion. Linear distraction is performed first (10 mm is recommended) and must be continued throughout the angulation process to prevent the formation of a hinge point or premature consolidation. It is recommended that the patient or parents perform the linear expansion and that the angulation be performed by the surgeon. As mentioned previously, angulation will reduce the amount of linear expansion previously achieved.
Active elastic
and mechanical distraction is followed by an 8-week
period of consolidation. In some cases in which an
open bite has been closed, intermaxillary elastics may
be worn during the period of consolidation for skeletal
and dental retention.
The development of intraoral mandibular distraction devices progressed in two directions: further minitiarization of external devices and modification of available internal orthodontic expansion appliances
A technique starts by fitting preformed stainless steel crowns to one tooth on either side of the anticipated osteotomy site (usually the second molar and first bicuspid teeth). A rubber base impression is taken of the entire arch, and the distractor is fabricated on the cast by the laboratory. The stainless steel crowns are cemented before surgery. An osteotomy is made between the selected teeth, and the expanders are placed to complete the process. In some cases, space will have to be created between the teeth before the osteotomy. After a 3- to 4-day latency period, the device is activated 0.5 mm to 1.0 mm per day in two to four activations. The recommended consolidation period is 5 weeks.