Distraction osteogenesis : The entire concept and recent advancements

1. Seminar On
“ Distraction Osteogenesis”
Presented By:
Dr.Mrinalini Mathur
Dept. of OMFS

2. Contents
Introduction
History
Need
Indications
Advantages
Disadvantages
Biological Basis of Distraction Osteogenesis
Types of Distraction Osteogenesis
Phases of Distraction Osteogenesis
Factors Affecting Distraction Osteogenesis
Patient Evaluation
Treatment Planning
Selection of Distraction Devices
Types of Distraction Devices
Parts of Distraction Devices
Length of Distraction Devices
No. of Potential Vectors of Movement
Direction of Distraction

3. Contents
Distraction Device Orientation
Biological Vectors of Distraction
Placement of Distraction Devices
Transport Distraction Osteogenesis
Distraction Histiogenesis
Fabrication of Surgical Splint
Surgical Technique
Postoperative Period
Orthodontic Considerations
Future Growth and Overcorrection
Stability
Soft Tissue Changes
Application of Distraction Osteogenesis
Timing of Surgery
Complications
Current Concepts
Future Concepts
Distraction Osteogenesis v/s Orthognathic Surgery

4. Introduction
-Distraction osteogenesis is a biologic process of new bone formation between the surfaces of
bone segments that are gradually separated by incremental traction.
-The process is initiated when a traction force is applied to bone segments and continues till the callus
tissue is stretched.
-Distraction forces applied to bone also create tension in the surrounding soft tissues, initiating a sequence
of adaptive changes termed distraction histiogenesis.

5. History
In 1905, Codivilla performed first bone distraction-femur.
In 1954, Ilizarov began his work on the lower extremity using techniques that combined compression,
tension, and then repeat bone compression to heal fractured long bones with segmental defects.
Distraction osteogenesis remained a long-bone treatment till 1972, Snyder used a Swanson external fixator
to lengthen mandible of a dog.
In 1989, Joseph McCarthy performed the first distraction of the human mandible.
In 1993, first mid-face distraction with buried devices was performed by Steven R. Cohen.
In 1996, Chin & Toth performed LeFort III advancement with gradual distraction using internal devices.
McCarthy, Stelnicki and Grayson; DO of the mandible: A ten-year experience. Seminars in orthodontics ,Vol 5, Issue 1, March 1999, Pages 3-8.

6. Need?
There are limitations with acute advancement of osteotomized bone segments due to:
(a) Inability to stretch soft tissues so the surrounding soft tissues cannot adapt to the new position resulting in
degenerative changes, relapse and compromised function and aesthetics.
(b) Orthognathic surgery can only be taken up after active growth ceases unlike distraction which can be
performed in infancy too.

7. Indications for Maxillofacial
Distraction Osteogenesis
 Severe maxillary deficiency in the transverse, vertical and antero-posterior planes
 Severe mandibular deficiency in the transverse, vertical and antero-posterior planes
 Temporomandibular joint ankylosis
 Condylar hypoplasia
 Obstructive sleep apnea
 Neonatal upper airway compromise
 Hemifacial microsomia
 Treacher Collins Syndrome
 Mandibular segmental defects after tumor ablation or trauma
 Craniosynostosis
 Vertical and horizontal alveolar ridge deficiency
 Clefts

8. Contraindications for Maxillofacial
Distraction Osteogenesis
 Inadequate bone stock as in neonates
 Geriatric patients due to delayed healing
 Irradiated bone
 Osteoporotic bone
 Any systemic disease which effects bone metabolism
 Contraindicated general anesthesia

9. Advantages of Distraction
Osteogenesis
 Ability to lengthen bones to a greater degree than would be possible with orthognathic surgery
 Can be applied at any age
 Soft tissues are stretched slowly so they gradually adapt to the bony movements and result in potentially
less relapse
 The mandibular condyle and disk position gets additional time to adapt to the rotational changes that
occur during distraction over a period of weeks
 No additional donor site morbidity from the need for bone graft harvesting
 In adolescent cleft patient undergoing maxillary advancement there is theoretical lower incidence of
velopharyngeal incompetence development or worsening

10. Disadvantages of Distraction
Osteogenesis
 Increased cost
 Additional time required for the entire treatment process
 Potential surgeon inexperience with a highly technique sensitive procedure
 Need for parent patient cooperation
 Facial scarring(pin tracts) from external devices
 Premature fusion of segments
 Malunion
 Device hardware problem
 Relapse with the need for initial overcorrection
 Need for second surgery to remove distraction device

11. Biological Basis of Distraction
Osteogenesis
Traction force applied to segments lead to stretching of callus.
This generates tension in the tissue stimulating new bone formation parallel to vector of distraction.
In addition, it also creates tension in the surrounding tissues, initiating a sequence of adaptive changes in the
surrounding tissues known as distraction histiogenesis.

12. Ilizarov’s Effects
Illizarov is known as the “father of distraction osteogenesis”. He popularized:
1) Tension-Stress Effect
Increased cellular activity and metabolic response with neovascularization leads to ossification of the site
with bony union without the need for bone grafting.
2) The mass or shape of these bones and joint articulations depends to a great extent on
:the available blood supply to the area
:functional burden placed upon the bones (Wolff’s Law)

13. Types of Distraction Osteogenesis
Depending on the place where tensional stress is induced, distraction can be classified as:
(a) Physeal distraction
(b) Callotasis
• Physeal distraction is the distraction of the bone growth plate and can either be-
Distraction Epiphysiolysis – where the separation occurs at 1-1.5 mm per day resulting in bone formation.
OR
Chondrodiatasis- where a slow rate of separation less than 0.5 mm per day is done.
• Callotasis refers to gradual stretching of the reparative callus forming around bone segments interrupted
by osteotomy or fracture.

15. Phases of Distraction
Osteogenesis(Callotasis)
Surgical Procedure
Corticotomy
Device application
Latency Period
Activation Period
Consolidation Period
DO Device Removal

16. Osteotomy
• Osteotomy- is the surgical separation of the bone into two segments.
-For the long bones and the mandible, a corticotomy is performed, rather than a complete osteotomy in
order to preserve the endosteal continuity and blood supply in the distraction gap.
-This provides the most conducive environment for bone formation and is referred to as “ rotation
osteoclasis”.
-Corticotomy is done by micro-oscillating saw or rotary handpiece with a this fissure bur and a bone chisel
and osteotome are used to complete the fracture.

17. - In the mandible, the corticotomy is done depending upon the intended distraction vector:
horizontal vector-body
oblique vector-angle
vertical vector-ramus
- Care is taken not to involve the inferior alveolar canal or the developing tooth buds.
- For the maxilla, a true corticotomy is not possible owing to the thin nature of the bone so, a standard
Le Fort osteotomy is generally performed.
-The distraction device is applied before performing the corticotomy because the device and the planned
vector decide the angulation of the corticotomy.
-The distractor was positioned and temporarily fixed with monocortical screws. The osteotomy line was
marked at the midpoint between the stabilizing and the transport plates on the buccal cortex , the distractor
was then removed, and osteotomy completed.

18. - Before wound closure, the distraction device must be activated to confirm the movement of bone
segments, failure to achieve segment distraction must be corrected at this point. After that the device
should be deactivated.
- Extraoral devices are secured with transmucosal pins and intraoral devices are secured with standard
bone screws. In order to minimize pin tract scarring, pinch the skin and subcutaneous tissues
together between the pins during transcutaneous pin placement.

19. Latency Period
• Latency period- the interval between the initial surgical procedure(corticotomy and device
application) and the device activation typically ranging from 5 to 7 days.
- The primary reason for the delay is to permit the establishment of a fibrovascular bridge across
the endosteum of the bony segments that will act to support future bone formation during the
distraction period.
- This time delay is prudent because there is transient interruption of endosteal continuity and
vascularity owing to the osteotomy as well as postsurgical edema.
-Within 24 hours: vascular ingrowth
mesenchymal cell proliferation
24-72 hours: early stages of granulation tissue(fibroblasts and capillaries) formation begins.
So, within 5-7 days there is establishment of the supportive fibrovascular bridge across the
corticotomy site.

20. - Waiting too long results in: premature fusion of the segments with the inability to perform distraction.
- Not waiting long enough results in: the lack of a stable vasculature in the bony gap leading to non-union or
fibrous tissue interposed between the bony segments at the completion of distraction.
- This period is age adjusted:
for children: 2-3 days latency
for neonates: 0 day latency
for elderly: 7-10 days latency

21. Activation/Distraction Period
• Distraction Period- is that time when a traction force is applied to bone segments, and new bone, or
distraction regenerate, is formed within the intersegmentary gap.
There are two important variable in the activation
1. Rate:
Amount of distraction per day
2. Rhythm:
How frequently the devices is activated

22. 1. Rate: 1.0 mm per day
Small: risk of pre mature consolidation
Great: undue stress on soft callus resulting in thinning of all dimension in midportion of
regenerate and an “ hourglass” at distraction site
- According to age:
Children and adolescents- rate of 2mm/day
Neonates- rate of 3 to 5mm/day
- If the rate is too slow: premature fusion of the proximal and distal segments.
- If the rate is too rapid: fibrous nonunion because of the compromised microvasculature.

23. 2. Rhythm
-Continuous application of distraction force is ideal
-Clinically, application of the distraction is best performed by activating the device twice a day(0.5mm
twice a day)
-If the patient experiences discomfort ,then the rhythm should be altered to allow for a smaller incremental
application(0.25 mm four times a day)
Radiographic and schematic drawing demonstrating
five zonal structure of distraction regenerate
Radiolucent fibrous interzone(FZ)
Radiodense mineralizing zone(MZ)
Radiolucent zone of remodeling(RZ)
Residual host bone segments(RHBS)

24. - The rhythm of distraction should be incremental and intermittent instead of continuous. This has an
advantage of production of periosteal stresses that serves to enhance bone regeneration in the distraction
gap.
- During osteodistraction, the normal process of healing is interrupted by the application of gradual traction
to the soft callus. The tension stress that develops in the gradually stretched tissues stimulates changes at the
cellular and subcellular levels.
- These changes can be characterized as:
:growth-stimulating effect
:shape forming effect
They result in the formation of primary trabeculae by the second week of distraction.
- The regenerate is moldable at this stage, so
orthodontic elastics could be used to change the occlusal relationship
vector correction can be done
• tissue.

25. - If a large movement is being achieved with distraction, then the callus can tend to become thinned
as it is stretched over a long distance.
- A process described as ‘pumping the regenerate’ may be carried out to prevent this.
- The patient is asked to turn his/her activation screw alternately forwards and then backwards to
prevent calcification and allowing more callus to develop.
- Pumping the regenerate technique is also used in bilateral cases where one side requires more
movement than another, such as in asymmetry cases.

26. Consolidation Period/ Period of
Neutral Fixation
• Consolidation Period- is the time for bony consolidation that occurs between the completion of distraction
and the removal of the distraction device.
- In adults usually 8 to 12 weeks.
- The consolidation period should be twice the distraction period.
- Detected radiographically by documenting the presence of a bony cortex or sufficient bone fill in the
distraction gap.

27. - Can be accelerated by treating the gap with either;
:chemical factors, such as growth factors, cytokines, and interleukin-6
:physical factors like ultrasound stimulation, low-level laser stimulation and electromagnetic therapy
Radiograph and schematic drawing demonstrating
structure of distraction regenerate during
consolidation period
Radiolucent zone of remodeling(RZ) adjacent to the
residual host bone segments(RHBS) and
divided by the mineralization zone (MZ)

28. Remodelling
• Remodeling period is the period from the application of full functional loading to the complete
remodeling of the newly formed bone.
- It takes a year or more before the structure of newly formed bony tissue is comparable to that of the pre-
existing bone.
- The regenerated segments of bone show a relatively low mineral content and radiodensity.
Schematic drawing demonstrating structures of distraction
regenerate during remodeling period
Gradual corticalization of the remodeling zone (RZ) with
formation of medullary canal (MC)is seen.
RHBS, Residual host bone segment
CB, Cortical bone

29. Histology
Histologic Appearance of Bone in The Distraction Gap
1- fibrous zone 3- remodeling zone
2- transition zone 4- zone of mature bone

30. Factors Affecting Distraction
Osteogenesis

31. Patient Evaluation
• Extraoral Examination
– Forehead, orbit, zygoma, external ear
– Oral commissure, chin, mandibular angles
• Intraoral Examination
– Occlusion
– Occlusal plane
• Function
– Maximum interincisal opening
– Mandibular deviation or deflection
– TMJ evaluation
– Nerve function

32. • Diagnostic Records
-Standard extraoral(frontal, profile, bird’s eye and worm’s view) and intraoral photographs(occlusion) with the
patient in Natural Head Position)
-Dental models articulated on a semi-adjustable articulator
-Lateral and PA cephalograms
-OPG
-CBCT
-Periapical radiographs
-CT Scan
-Stereolithographic models
Thorough clinical examination to reveal the structural abnormalities and functional deviations that require
correction. This information is coupled with an understanding of the patient's expectations to finalize the
treatment planning

33. Treatment Planning
• Osteotomy design and location
• Selection of a distraction device
• Determination of the distraction vector
• Duration of the latency period
• Rate and rhythm of distraction
• And duration of the consolidation period

34. Selection of Distraction Device
The choice of distraction device depends upon-
specific anatomic abnormality
desired distraction vector
overall magnitude of bony movement
planned surgical access
access for device activation
patient and parent preferences
surgeon experience

35. Types Of
Distraction
Devices

36. Types of Intra-oral Distraction Devices

37. Extraoral Distraction Devices
Advantages
• Small children applicability
• Simplicity of attachment
• Ease of manipulation
• Multiplanar adjustment
• Low infection rate
Disadvantages
• Apprehension
• Bulky appliance
• Social inconvenience
• Facial scars
• Reduced consolidation period
• Pin tracts
• Pin loosening

38. Intraoral Distraction Devices
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
• Require 2nd surgery to remove

39. Extraoral Vs Intraoral Distraction
Devices
Internal devices are more comfortable to the
child with a precise and predictable vector of
lengthening and lower risk of relapse. They
leave less visible scars and should be
considered first. Their main disadvantage is
the second operation for device removal under
general anesthesia. The external devices are
easier to fit even in severely hypoplastic
mandibles, permit greater distraction length,
and can be removed simply by unscrewing the
pins. Therefore, in cases where internal device
placement is impossible or when there is need
for greater distraction length, external devices
may be used while considering greater child
discomfort and risk of pin loosening that may
compromise consolidation and increase risk of
relapse.
Rachmiel A, Nseir S, Emodi O, Aizenbud D: “External versus Internal Distraction Devices in Treatment of Obstructive Sleep Apnea in Craniofacial Anomalies”;Plast
Reconstr Surg 2014;2:e188.

40. Rigid External Device
-Rigid external distraction(RED)device enables to manage patients with
severe maxillary hypoplasia in cleft and craniosynostosis cases.
-The RED system consists of :
Cranial halo – Provides skeletal anchorage & is attached using scalp
screws
Vertical bar – Extends from cranial halo & is used to attach the
horizontal bar
Horizontal bar – Carries the distraction screws which are attached to the
eyelet of the splint with a surgical wire so that the
forces are applied to the maxilla
- Vector of distraction can be controlled by adjusting the position of the
horizontal bar & the eyelets.
-Latency period – 3-4 days
Rate of distraction – 1mm/day
Consolidation period – 2-3weeks

41. Parts of Distraction Devices
(1) Sleeve for the distraction screw
(2) Fixed block comprising of three-hole stainless steel triangular bone
plate fixed to the medial fragment with the help of three 2mm
monocortical screws
(3) Movable block also comprising of 3-hole stainless steel triangular
bone plate fixed to the distal fragment which moves along the threaded
rod with the fragment at the time of distraction
(4) Threaded central rod each thread of the rod has the pitch of 0.5mm,
therefore one turn of 360°brings about distraction of 0.5mm. The
appliance is designed in such a way that a maximum of 25mm
distraction is achieved
(5) Two guiding supporting rods one above and one below the central
threaded rod in parallelism with the central threaded rod
(6) 3-hole stainless steel triangular bone-plate used for fixation of
distraction appliance
(7) Stabilizing plate holding the threaded rod and the two guiding plates
together at the posterior end of the assembly
(8) A special custom-made screwdriver is manufactured to fi t in the slot
of the distraction screw

42. Length of Distraction Devices
-In order to complete the desired amount and angulation of distraction, the appropriate length of distraction
device must be selected.
-Magnitude of lengthening is registered on distraction device.
-The amount of bone distraction clinically observed during lengthening is a result of linear device
activation altered by the effect of extrinsic and intrinsic biomechanical factors.
-When angular correction is incorporated into linear activation, the total amount of linear distraction
decreases even more, further increasing the length requirement of the distraction device.
- The maximum length of distraction regenerate is equal to the length of the distraction device.
- Right and left maxillary and mandibular distractors are separately available. They are available in 4 sizes,
10 mm, 15 mm, 20 mm and 25 mm. So, a maximum of 25 mm distraction is possible.

43. No. of Potential Vectors of Movement
- Monovector devices usually require only one corticotomy (horizontal, vertical or oblique) and use a single
device to achieve simple linear elongation of the bone in a vertical, horizontal or oblique direction.
- Bidirectional devices may require two corticotomies performed perpendicular to each vector and use of a
specific device to achieve both vector movements, or a specialized device maybe used with only one
corticotomy to achieve biplanar movement.
- Multivector devices require a single oblique osteotomy.

44. Dancing Distraction
- Micrognathia patients present with bilateral hypoplasia that affects both
the mandibular body and ascending ramus.
- Two corticotomies are done: one vertical in the mandibular body and other
horizontal in the ascending ramus.
- A biplanar distraction device is used. It has 3 pins. A central pin at the
mandibular angle between the two corticotomies, a second pin in the
mandibular body and a third pin in the ascending ramus.
- One bidirectional device is used on each side. Each device has two
distraction plates to allow independent elongation of the ramus and the
body with the central pin at the angle acts as a fixed pivot.

45. Direction of Distraction
- Distraction vector defines the desired direction that the distal segment must move during lengthening.
- For a simple linear advancement, a unidirectional distraction device is suitable.
- If lengthening of the jaw is planned in two or more directions, a multidirectional device is required.
- Ideally devices should be placed parallel to the vector desired in order to avoid adverse
biomechanical effects.
- Factors that affect the vector of distraction include:
• osteotomy design and location
• distraction device orientation
• masticatory muscle influence

46. Distraction Device Orientation
Vectors of distraction
Straight lines indicate the long axis of the device.
Vertical (A)
Horizontal (B)
Oblique (C)
-The line represents the long axis of the device in relation to the long
axis of the mandibular body.
-In this planning method, the authors did not orient the device in
relation to the posterior border of the ramus or the inferior border of
the mandible because of the variability in morphology of these
borders.
Grayson B, Santiago PE: Treatment planning and biomechanics of distraction osteogenesis from an
orthodontic perspective. Semin in orthod 5:9-24,1999
PP 9-24

47. Vertical Device Placement
-Activation of the device results in an increase in the vertical
height of the ramus
-Vertical distraction along the long axis of the ramus results
in oblique distraction as the ramus is not at right angles to the
occlusal plane. So, ideally the distractor should be placed
perpendicular to the occlusal plane.
-A vertical vector is: perpendicular to the occlusal
plane
perpendicular to the long axis
of the mandibular body
achieved with a horizontal
osteotomy cut

48. -The mandible autorotates in a counter- clockwise
direction, the lower incisors take a more advanced
position, and a posterior open bite may present itself on
the side that has been lengthened vertically.
-Bilateral vertical lengthening of the ramus is associated
with counterclockwise up- righting of the symphysis.
This, along with sagittal advancement of the mandibular
body, contributes to the perception of increased
prominence of the lower third of the face.
Grayson B, Santiago PE: Treatment planning and biomechanics of distraction osteogenesis from an orthodontic perspective. Semin in orthod 5:9-24,1999 PP 9-24

49. Horizontal Device Placement
-A horizontal vector is: parallel to the occlusal
plane
parallel to the long axis
of the mandibular body
achieved with a vertical
osteotomy cut
-Activation of the device results in an increase in the
anteroposterior dimension of the mandibular body with
increased sagittal projection of the symphysis

50. -There is a tendency in horizontal distraction for the body
to rotate in a clockwise direction, sometimes resulting in
open bite
-The pull of the suprahyoid musculature may have a role
in this occurrence
-There has been a reported improvement in patency of the
oropharyngeal airway and tongue position after
mandibular sagittal advancement
Grayson B, Santiago PE: Treatment planning and biomechanics of distraction osteogenesis from an orthodontic perspective. Semin in orthod 5:9-24,1999 PP 9-24

51. Components of horizontal and vertical distractors

52. Oblique Device Placement
-Oblique device placement results in an increase in both the vertical and horizontal dimensions of the
ramus and body.
-The effect of oblique device placement is a combination of the vertical and horizontal changes.
-Overjet and both ramal and body size deficiency may be addressed by oblique device placement.
-When an oblique device orientation is chosen, anteroposterior positional changes occur along with
hyper divergence of the mandible, resulting in clockwise rotation and anterior bite opening.

53. -In patients with a deep bite, this may be advantageous. In most cases, however, clockwise mandibular
rotation results in an undesirable anterior open bite.
-The oblique orientation of the distraction device may be changed to either more vertical or more
horizontal depending on whether the ramus or mandibular body requires more lengthening, respectively.
-Corticotomy is performed at an angle between 0°(the vertical vector) and 90°(the horizontal vector) to
the occlusal plane, generally in the angle region of the mandible.

54. Biological Vectors of Distraction

55. Placement of Distraction Devices
• In cases with simultaneous ramus and corpus lengthening, the distractor may be placed according
to the simple formula:
Pin Placement Angle =180 - Gonial Angle x Ramus Deficiency
Total deficiency(vertical+horizontal)
• Where Pin Placement Angle = the angle between the distraction vector and the mandibular plane.
Gonial angle= Condylion-gonion-menton
is formula was tested and modified with more
• The amount of distraction can also be calculated using a formula:
Distraction Amount = Dc + Dr - 2(Dc x Dr) x cos a
where Dc = corpus deficiency, Dr = ramus deficiency,
a = gonial angle.

57. Transport Distraction
Osteogenesis(TDO)
• TDO can be best explained as a creation of bone and soft tissue to fill a defect by moving a disk of
bone and formation of new tissues behind it until the disk docks the receiving host bone.

58. Indications:
-segmental defects of the mandible( 3-12cm defects) as a result of
ablative surgery for odontogenic tumors, surgical removal of
cancers, chronic bone infections, blast injuries, gunshot wounds,
etc.
-neocondyle regeneration
-distraction for calvarial defects
-achieving alveolar height for prosthesis
-maxillary alveolar defects

59. Surgical Principles of TDO
-Transport distraction involves creating a transport disk in the residual host bone stump, adjacent to a
discontinuity defect or a resection site.
-The transport disk is then advanced 1.0-mm per day to span the discontinuity defect.
-As this transport disk advances towards the target host bone segment, callus forms at its trailing end,
which gradually matures and calcifies.
-Steps of TDO:
Osteotomy of the bone site with minimal periosteal stripping
latency period of 5–7 days before activation
distraction rate of 1.0-mm per day
twice a day distraction rhythm
consolidation until a cortical outline can be seen radiographically across the distraction gap, usually 6
weeks

60. -Once the transport disk reaches the docking site, the segment is held in neutral fixation until a cortical
outline is seen in the regenerate.
-At the time of distractor removal, a small bone graft may need to be positioned between the transport disk
and the docking site because the transport disk becomes rounded and encased with a fibrocartilaginous cap
on the advancing front.
-This intervening fibrocartilaginous cap must be removed for osseous union between the disk and docking
site. But this fibrocartilaginous capping between the transported bone segment and the glenoid fossa
acts as disk of the neocondyle.

61. The transport distraction device may be divided into three basic
components:
:the reconstruction plate for stability
:distractor component for mobilizing the transport disk on activation
:screws for assembling and securing the device
Ramus Transport Distractors
Devices for transport distraction of the condylar head
Transport Distraction Osteogenesis for Maxillomandibular Reconstruction: Current Concepts and Applications: R. S. Neelakandan, Darpan Bhargava. J.
Maxillofac. Oral Surg. (July-Sept 2012) 11(3):291–299

62. Distraction Histiogenesis
-More than 10 mm advancement of maxilla, and mandible is restricted due to inability of the soft tissue
envelope to stretch beyond a certain degree.
-When gradual distraction forces are applied across the osteotomy, not only the callus elongates but also,
the soft tissues grow in response to mechanical stress.
-The soft tissue grows and is not just merely stretched. Hence, the term is “distraction histiogenesis.”
-The advantages are:
Advancements can be performed safely, without the restrictions of soft tissue envelope
Complex three dimensional deformities can be corrected by multiplanar distractors
The risk of relapse is minimized

63. Fabrication of Surgical Splint
A) B) C)

64. D) E) F)
Procedure for fabrication of a modified Kingsley splint for maxillary distraction osteogenesis S. Venkat Aditya, Anil Kumar Gujjari

65. Surgical Technique

66. Surgical Technique
Distraction of Craniofacial Skeleton. Jeffrey Hollinger, Michael H. Mayer, Joseph G. McCarthy

67. Postoperative Period
- Latency period:5-7 days
Activation period: 1mm per day, 0.5mm twice daily
Consolidation period:8 weeks
-The progress of distraction is monitored by documenting changes in the relationships of the
anterior maxillary and mandibular occlusion and the position or level of the occlusal plane, oral
commissure, and chin point.
-The device is not removed until there is radiographic evidence of a cortical outline or
mineralization of the regenerate portion of the mandible (neomandible).
-Upon removal of the pins and distraction device, photographs, lateral and posteroanterior
cephalograms, panorex, and 3D CT scan of the mandible are obtained.

68. Orthodontic Considerations
-The role of orthodontics in treatment using distraction osteogenesis falls into three temporal phases:
: Predistraction treatment planning and orthodontic preparation
:Orthodontics during distraction and consolidation
:Post consolidation orthodontic management

69. PRESDISTRACTION ORTHODONTICS
- Maxillary and mandibular dental arches are prepared for distraction osteogenesis by levelling, alignment,
decompensation and correction of curve of Spee.
- Teeth should be moved to ideal position relative to the basal bone so that ideal maxillomandibular
relationship is not compromised by existing dental compensation.
- Placement of arch wires with hooks for engaging inter-arch elastic during and after distraction.
- Fabrication and use of distraction stabilization appliances.

70. ORTHODONTICS DURING DISTRACTION AND CONSOLIDATION
- Orthodontic/orthopedic treatment may include the use of bands, brackets, distraction stabilization
appliances, elastics, headgear, maxillary expansion appliances etc.
- The “floating bone concept” of Hoffmeister where the device is removed before consolidation and
orthodontic forces are used to achieve the treatment end position before allowing consolidation of the
callus.
- Closely monitor the patient during the active distraction phase, using intermaxillary elastic traction,
sometimes combined with guide planes, bite plates, and stabilization arches, to mould the newly formed
bone (regenerate) while optimizing the developing occlusion.
Hoffmeister B, Marks CH, Wolf KD; International Journal of Oral and
Maxillofacial Surgery, Volume 28, Supplement 1, 1999, Page 90

71. -Intermaxillary elastics can be used to modify the direction of skeletal change and fine tune the occlusal
outcome of distraction.
- Intermaxillary elastics may be helpful in the reduction of an anterior open bite and may be used
transversely to correct crossbite or lateral shift of the mandible during active distraction.
POST-DISTARCTION ORTHODONTIC MANAGEMENT
- It includes eruption guidance and final alignment of the dentition including closure of any open bite.
- The open bite may be managed with gradual adjustment of a bite plate.
- The crossbite resulting from mandibular shift across the midsagittal plane may be corrected by a
combination of transpalatal arches, lingual arches, intermaxillary cross elastics, and a palatal expansion
devices.
Grayson B, Santiago PE: Treatment planning and biomechanics of distraction osteogenesis from an orthodontic perspective. Semin in
orthod 5:9-24,1999 PP 9-24

72. Future Growth and Overcorrection
- Structural & functional result with distraction is definitive for skeletally mature patients.
- It may be a temporary treatment objective for growing patients.
- Skeletal age and future growth potential must be considered in these individuals.
- This parameter is calculated based on the duration of remaining mandibular growth and percent of yearly
growth deficiency.

73. Stability After Distraction Osteogenesis
- Wiltfang J, Hirschfelder U, Neukam FW, Kessler P. Long-term results of distraction osteogenesis of the
maxilla and midface. Br J Oral Maxillofac Surg 40:473, 2002.
Intraoral distraction 5.55% relapse
Extraoral distraction 7.92% relapse
- Strijen PJ, Breuning KH, Becking AG, Tuinzing DB. Stability after distraction osteogenesis to
lengthen the mandible: Results in 50 Patients. J Oral Maxillofac Surg 2004;62:304-307.
Concluded that high-angle patients are at risk of relapse. For low-angle patients, however distraction
is a safe and predictable procedure.
- Triaca CU, Antonini M, Kiliaridis S, Jagtman AM. Skeletal and dental stability of segmental distraction
of the anterior mandibular alveolar process: A 5.5-year follow-up. Int. J. Oral Maxillofac. Surg. 2013; 42:
337–344.
The relapse measured 8.3% at point B and 29.0% at incision inferior .

74. Soft Tissue Changes After Distraction
Osteogenesis
- In 2006, Melugin et al. evaluated the effects of Mandibular Distraction Osteogenesis on the hard to
soft tissue movement ratio.
A mean advancement ratio of 1:0.9 for point B/Labiomental sulcus (LMS) and Pogonion/Soft t
tissue Pogonion (Pg/Pgs) was observed.
·LMS
·Pog´
Melugin MB, Hanson PR, Bergstrom CA, Schuckit WI, Bradley TG. Soft
tissue to hard tissue advancement ratios for mandibular elongation using
distraction osteogenesis in children. Angle Orthod 2006;76: 72–6.

75. Neocondyle Distraction Osteogenesis

76. Neocondyle Distraction Osteogenesis
Sharma R , Manikandhan R, Sneha P, Parameswaran A, Kumar JN, Sailer HF. Neocondyle distraction osteogenesis in the management of
temporomandibular joint ankylosis: Report of five cases with review of literature. Indian J Dent Res 2017;28:269-74.

77. Obstructive Sleep Apnea
Preoperative (A) and
postoperative (B)
cephalometric radiographs.
Note the increase in airway
space behind the tongue base.
Kasey K. Li. Distraction osteogenesis and obstructive sleep apnea syndrome. Operative Techniques in Otolaryngology (2006) 17, 257-261

78. Mandibular Distraction Osteogenesis
Indications-
Sagittal deficiency
Inadequate vertical length
Transverse deficiency
Obstructive Sleep Apnea
Congenital deformities like Hemifacial Microsomia,
Treacher Collin’s syndrome etc.
Alveolar defects

79. Midface Distraction Osteogenesis
Indications-
Midface hypoplasia
Orofacial clefts
Craniosynostosis
Alveolar defects
Combined Maxillary And Mandibular Distraction
Osteogenesis
Indication-
Hemifacial microsomia and Treacher Collins Syndrome

80. Alveolar Distraction Osteogenesis
Indications:
• Atrophic alveolar process due to periodontal disease,
• Trauma or congenital deformity
• Segmental deficiencies of the ridge that compromise the implant
placement
• Defect due to removal of pathology
• Narrow alveolar ridges
• Gradual vertical shift of an osseointegrated implant along with
surrounding alveolar bone

81. Contraindications:
• Severely atrophic mandible
• Osteoporosis
• Advanced age
Types of devices:
• Extraosseous or subperiosteal distractor
• Endosseous distractor
• Endosseous distraction implant : This represents a combination of distraction device and an endosseous
dental implant
Advantages of alveolar distraction:
• No morbidity of donor area
• Less possibility of hard tissue exposure and less chances of graft resorption
• More predictable volume of bone
• Shorter bone consolidation period

82. Craniofacial Distraction
Osteogenesis
Syndromic craniosynostosis including Crouzon, Apert
and Pfeiffer syndrome in which patients may suffer
serious functional problems associated to increased ICP,
severe exorbitism and OSA secondary to structural
growth abnormality related to the early fusion of cranial
sutures. Patients with these problems often require
massive segmental expansion of the skull and midface
region to decompress the restricted intracranial space,
achieving orbital protection and eyelid closure as well as
opening up the nasopharyngeal space to treat the
respective functional issues.

83. Timing of Surgery
Early corrections have the following benefit
1- Psychological development
2- As the problem has not developed completely yet, early treatment translates to less potential insult to the
system, reduced risk of relapse and better long term stability.
3- Better healing
4- Optimize growth potential by placing structures in a more normal anatomic position
5- Releasing restricted growth of adjacent skeletal structures
6- Improve the appearance
a
7- Certain conditions like life-threatening upper airway obstruction in children with Pierre Robin
Syndrome demand early surgical intervention

84. Complications of Distraction
Osteogenesis
Timing Complication
Intra-operative Incomplete bone fracture
Nerve damage
Problems with the device: instability, breakage
Generic surgical risk: bleeding, swelling, pain
Damage to developing tooth buds with pin
During distraction Patient compliance in activating the distractor
Pain
Premature calcification of the bone
Problems with the device: instability, breakage
Infection
Damage to the teeth if tooth-borne distractor is used

85. Complications of Distraction
Osteogenesis
Timing Complication
Post distraction Malunion or failure of callus to heal
Relapse
Persistent nerve damage
Hypertrophic scarring
TMJ changes

86. Complications of Distraction
Osteogenesis
1) RELAPSE
- Relapse is defined as any increase in sagittal overbite from the immediate postoperative sagittal overbite
measurement following MDO.
- However, many argue that relapse (as defined above), is not a complication but rather an unavoidable
consequence of performing MDO in the skeletally immature.
- In this case, relapse or regression is due to the inherently retarded growth of the mandible relative to the
natural progression of maxillary growth.
- If one accepts the above definition of relapse, then relapse is the most reported complication or outcome of
MDO in the skeletally immature.
- This is particularly true when performing MDO in skeletally immature syndromic children.
- Gursoy et al followed 10 growing (mean age of 7.6 years at the time of MDO) syndromic children after
performing external, bilateral MDO for a mean of 5 years postoperatively.

87. - He specifically evaluated these patients for any evidence of regression toward the original preoperative
deformity and found that excellent short-term results with MDO were not stable during growth in these
syndromic children.
- As such, they recommended performing MDO only in skeletally immature syndromic children to correct
severe airway problems. In the remainder of patients, it is preferable to wait until closer to skeletal maturity to
perform MDO.
- In skeletally mature patients undergoing bilateral MDO, specifically, patients with a high mandibular angle
(i.e., >38°) demonstrate a 57% incidence of relapse at 1 year.
- In contrast, patients with low to normal mandibular angles (i.e., ≤38 degrees) demonstrate only an 8.3%
incidence of relapse at 1 year. However, the rate of relapse or regression after MDO in skeletally mature
syndromic children has not been studied with relation to mandibular angle, so it is not clear if these finding
apply also to relapse in this specific population.
TO AVOID: It may be advantageous to perform bilateral distraction of the mandibular ramus rather than
horizontal distraction of the body in patients with high mandibular angles. This strategy would increase
posterior mandibular height and further advance the chin point through the resultant mandibular autorotation

88. 2) TOOTH INJURY
- Tooth injury has been reported in up to 22.5% of cases.
- Typically, unerupted molar buds located high in the retromolar region are damaged at the time of
osteotomy and/or due to inappropriate pin placements.
- As a result of these injuries, up to 35% of patients may have subsequent distalization of the dental bud
to a more superior position in the mandibular ramus.
- In contrast, 12.5% of patients will sustain molar bud perforations, 5% will sustain dental root injuries
leading to subsequent root absorption, and 2.5% will form dentigerous cysts.
TO AVOID: Tooth injury may be avoided with the acquisition of preoperative imaging to determine the
precise locations of molar teeth and buds.The osteotomy and/or distractor pins should be placed far
enough from tooth buds so as not to interfere with subsequent tooth development.

89. 3) HYPERTROPHIC SCAR
- Hypertrophic scarring after removal of external distractors occurs in 0.67% to 15.6% of patients.
- Hypertrophic scars require revision in up to 14.3% of patients.
TO AVOID: Hypertrophic scarring can be avoided altogether by using an internal distractor or minimized
with an external distractor by modifying the operative technique. One method is to pull skin from below
the mandible before making incisions for pin insertion. This technique creates scars that may be partially
hidden underneath the mandible.

90. 4) NERVE INJURY
- Mandibular distraction osteogenesis can induce transient hypesthesia of the inferior alveolar nerve and/or
transient paraparesis of the muscles innervated by the marginal mandibular branch of the facial nerve.
- Transient hypesthesia of the inferior alveolar nerve (incidence of 3.6%-7.9%) is caused by stretching of
the nerve during active distraction.
- Furthermore, the incidence of hypesthesia is directly associated with the rate of distraction.
- Patients undergoing 1 mm of distraction per day or less have a 2.4% incidence of hypesthesia, whereas
patients undergoing greater than 1 mm of distraction per day have a 19.5% incidence of hypesthesia.
- Finally, the incidence of inferior alveolar nerve neuropraxia may also be related to the type of distraction
device. There is 2.44% incidence of neuropraxia in patients undergoing internal distraction of native bone
versus a 0% incidence in patients undergoing external distraction of native or grafted bone.
- Transient paraparesis of the muscles innervated by the marginal mandibular branch of the facial nerve
occurs less frequently (0.4%-3.5% incidence). This injury may be due to local irritation from external
distractor pins, or it may be due to overstretching of the nerve.

91. TO AVOID:
- The incidence of temporary hypesthesia of the inferior alveolar nerve may be decreased by
distracting only a maximum of 1 mm/d and using more than 1 distraction activation per day.
- Avoid full thickness saw cuts through the mandible and use the saw only on the buccal cortex; the
osteotomy is then completed by fracturing the lingual cortex.
- When performing osteotomies of the mandibular ramus, one can avoid injury to the inferior alveolar
nerve by placing the osteotomy transversely above the lingual foramen. However, one must be certain
that adequate bone stock remains to secure the distractor proximal to the level of the osteotomy, which
may be difficult in the hypoplastic mandible.
- Similarly, injury to the marginal mandibular branch of the facial nerve may be avoided by using an
internal distractor and/or by minimizing the total daily distraction rate.
- In addition, the use of intraoral incisions rather than external incisions for distractor placement also
decreases risk to the inferior alveolar nerve.

92. 5) INFECTION
- Infections range from superficial cellulitis to osteomyelitis with a 9.5% cumulative incidence.
- Pin-tract infections (1.3%-5.2% incidence) are most common followed by minor local infection
(1.2%-2.9% incidence).
- In addition, the incidence of minor infection can be further subdivided based on the type of distraction
device used and the quality of the bone being distracted.
- There is an 8.05% incidence of minor infection in patients undergoing external distraction of native bone,
a 7.32% incidence of minor infection in patients undergoing internal distraction of native bone, and an
8.33% incidence of minor infection in patients undergoing external distraction of grafted bone.
- Osteomyelitis and/or deep infection requiring removal of instrumentation is much less common with a
cumulative incidence of 0.5% -0.9%.
TO AVOID: Superficial cellulitis, pin-tract infections, and osteomyelitis may be minimized with the
administration of perioperative antibiotics to begin before the skin incision is made. In addition, patients
should learn to clean and dress their pin sites on a regular basis to decrease the incidence of pin-tract
infections.

93. 6) Inappropriate Distraction Vector
- Inappropriate distraction vectors have been reported in:
0.67% to 7.2% of cases with bidirectional distractors
8.8% of cases with monodirectional distractors.
- The incidence of improper vector can also be subcategorized based on:
the severity of the complication (minor, moderate, or major )
the type of distractor (external versus internal)
the quality of distracted bone (native vs grafted)
- 0.67% incidence in patients undergoing external distraction of native bone
0% incidence in patients undergoing internal distraction of native bone
- It often leads to a wide variety of interrelated clinical problems, including laterognathism and malocclusion.

94. - Laterognathism represents a sagittal rotation of the mandibular midline, which typically occurs in patients
undergoing unilateral mandibular distraction osteogenesis.
- In this instance, the mandibular midline rotates away from the side undergoing distraction due to excessive
magnitude of distraction or an inappropriate net distraction vector.
- In the absence of orthodontic appliance, laterognathism may lead to condylar displacement, condylar
resorption, and/or malocclusion consisting of a closed lateral bite and crossbite.
- This potential complication highlights the importance of concomitant orthodontic management throughout
the procedure and especially during the period of active distraction.
- Intermaxillary and/or maxillomandibular elastic traction, guide planes, bite plates, and stabilization arches
should be used to mold the newly formed regenerate and optimize developing occlusion.
TO AVOID: Meticulous preoperative planning including radiographs and CT imaging.
-Laterognathism and midline shift are best addressed by adding an additional site of vector control during the
distraction process, thereby helping to guide the final position of the mandible beyond the control achieved
with distractor placement alone. This can be accomplished with concomitant orthodontic management
consisting of distraction stabilization appliance and interdental elastic traction.

95. 7) Device Failure
- Device failure including both breakage and dislodgement occurs with a cumulative incidence of 7.5% to
7.9%.
- Device breakage may occur in up to 4.5% of cases and can be caused by premature consolidation.
- In contrast, loosened or dislodged devices (3% incidence) may be due to impingement of the device with
bony structures during range of motion, bone quality, and/or inadvertent trauma.
TO AVOID:
- Device dislodgement and/or breakage can be avoided with careful preoperative planning and
intraoperative placement of the distractor so as to avoid any impingement of the distractor with
surrounding structures.
- One must confirm that a complete osteotomy has been achieved, because pin retention may not be strong
enough to overcome any impingement in mandibular lengthening.
- If premature consolidation is encountered, early recognition by radiographic examination and/or
increased resistance to distractor movement can help to avoid device dislodgement or failure.

96. 8) Fusion Error
- Fusion error occurs in 2.4% of cases.
- Errors include both premature consolidation and fibrous nonunion.
- Premature consolidation occurs in 1.9% of cases and may be due to an incomplete osteotomy, an
excessive latency period, inadequate daily distraction rate, and/or device failure.
- Fibrous nonunion occurs in 0.2% to 0.5% of cases. This complication may be due to a truncated
latency period, a large daily distraction rate, waiting an inadequate amount of time after a previous
fusion, or an excessively frequent distraction rhythm.
TO AVOID: Select an appropriate latency period and a suitable rate and rhythm for distraction.

97. 9) TMJ Injury
- The least common complication of mandibular distraction osteogenesis is TMJ ankylosis and degenerative
changes occurring in approximately 0.7% of cases.
TO AVOID:
- Use the appropriate distraction vector so as to prevent laterognathism, condylar resorption, and/or
condylar displacement.
- The osteotomy should be placed below the sigmoid notch to prevent dislodgment and impingement of the
coronoid process on the zygomatic arch.
Master DL, Hanson PR, Gosain AK. Complications of Mandibular Distraction Osteogenesis. J Craniofac Surg 2010;21: 1565-1570)

98. Current Concepts
1)

99. 2)

100. 3)

101. 4)

102. 5)

103. Future Concepts
• Endoscopic technique
• Resorbable devices
• Osteotomy free distraction across suture sites in infants
• VGEF adenovirus & BMP-2 adenovirus show earlier ossification
• Endothelial progenitor cells (Adult stem cells)

104. Distraction Osteogenesis V/S
Orthognathic Surgery
Ramanathan M, Kiruba GA, Christabel A,
Parameswaran A, Kapoor S, Sailer HF. Distraction
Osteogenesis Versus Orthognathic Surgery:
Demystifying Differences in Concepts, Techniques and
Outcomes. J. Maxillofac. Oral Surg.