Distraction osteogenesis (5)

Distraction Osteogenesis-Distraction Osteogenesis-Principles and MethodsPrinciples and Methods

OLALEKAN T. OmoniyiOLALEKAN T. Omoniyi

Definition- 1Definition- 1 Distraction Osteogenesis is the ability to induce Distraction Osteogenesis is the ability to induce

callus in bone (by an osteotomy or sectioning) callus in bone (by an osteotomy or sectioning) and then distracting the proximal ends.and then distracting the proximal ends.

It relies on prolonged, controlled, progressive It relies on prolonged, controlled, progressive and gradual distraction which does not disrupt and gradual distraction which does not disrupt the vascular supply.the vascular supply.

This results in simultaneous expansion of This results in simultaneous expansion of soft tissue and bone volume. soft tissue and bone volume.

Definition-2Definition-2 It is the ability to reconstruct combined It is the ability to reconstruct combined

deficiencies in bone and soft tissue that deficiencies in bone and soft tissue that makes this process unique and invaluable makes this process unique and invaluable to all types of reconstructive surgeons to all types of reconstructive surgeons

Two main cellular processes are involved: Two main cellular processes are involved: the formation of a callus and the the formation of a callus and the generation of new bone.generation of new bone.

HistoryHistory

In 1988, the Russian orthopaedic surgeon Ilizarov In 1988, the Russian orthopaedic surgeon Ilizarov described a technique for DO involving only a described a technique for DO involving only a corticotomy-interruption of the cortical bone alone, with corticotomy-interruption of the cortical bone alone, with minimum disruption of the periosteum and endosteum minimum disruption of the periosteum and endosteum hence reducing the incidence of morbidity.hence reducing the incidence of morbidity.

Interestingly,Ilizarov’s intention was to use external Interestingly,Ilizarov’s intention was to use external compression to bone ends in order to treat cases of non-compression to bone ends in order to treat cases of non-union.A patient who had failed to grasp the instruction union.A patient who had failed to grasp the instruction given, turned the screw the wrong way and ended up given, turned the screw the wrong way and ended up distracting rather than compressing their bone distracting rather than compressing their bone ends.Ilizarov took radiographs and noticed new bone ends.Ilizarov took radiographs and noticed new bone being formed.being formed.

ApplicationsApplications Lengthening of the mandible.Lengthening of the mandible. Advancing the midfaceAdvancing the midface Augmenting the mandibular alveolar ridge.Augmenting the mandibular alveolar ridge. Has provided options for treatingHas provided options for treating Hypoplastic mandiblesHypoplastic mandibles Missing boneMissing bone Unilateral and bilateral microsomiaUnilateral and bilateral microsomia MicrognathiaMicrognathia Calvarial expansionCalvarial expansion

Treatment Phases of DOTreatment Phases of DOPre-surgical phasePre-surgical phaseOperative phaseOperative phaseLatency phaseLatency phaseDistraction phaseDistraction phaseConsolidation phase and Consolidation phase and Retention phase. Retention phase.

Pre-surgical phasePre-surgical phase Involves radiographic studies to determine the feasibility Involves radiographic studies to determine the feasibility

of placement of the distraction device, the vector of placement of the distraction device, the vector (direction, amplitude) of the distraction, and whether an (direction, amplitude) of the distraction, and whether an internal or external device is more appropriate.internal or external device is more appropriate.

When possible, 3-D solid models help to visualize the When possible, 3-D solid models help to visualize the placement of the device and simulate the distraction placement of the device and simulate the distraction process. process.

Involvement of the orthodontist is essential as Involvement of the orthodontist is essential as presurgical orthodontic preparation typically is needed to presurgical orthodontic preparation typically is needed to guide the distraction at the occlusal level since the guide the distraction at the occlusal level since the skeletal component is controlled by the device skeletal component is controlled by the device mechanism. mechanism.

Operative phase – Guidelines for Operative phase – Guidelines for Mandibular Distraction -1Mandibular Distraction -1

Make sure that there is adequate mandibular bone stock Make sure that there is adequate mandibular bone stock for the osteotomy and placement of the device. for the osteotomy and placement of the device.

Decide on the type of device. External devices allow for Decide on the type of device. External devices allow for multidirectional control of the distraction, which cannot multidirectional control of the distraction, which cannot be achieved with the currently available internal devices. be achieved with the currently available internal devices. However, external devices may lead to significant facial However, external devices may lead to significant facial scarring, and the application of sequential different scarring, and the application of sequential different distraction vectors with a series of internal devices may distraction vectors with a series of internal devices may be preferable to a permanent external scar. be preferable to a permanent external scar.

Exposure can be obtained through either an intraoral or Exposure can be obtained through either an intraoral or extraoral approach, depending upon the exposure extraoral approach, depending upon the exposure required for the placement of the device and the required for the placement of the device and the allowable maxillary-mandibular opening. allowable maxillary-mandibular opening.


The placement and/or direction of the device, not the The placement and/or direction of the device, not the osteotomy of the mandible, dictates the distraction osteotomy of the mandible, dictates the distraction vector. The osteotomy line does not necessarily need to vector. The osteotomy line does not necessarily need to be perpendicular to the distraction vector but should be be perpendicular to the distraction vector but should be placed to avoid injury to the nerve and the developing placed to avoid injury to the nerve and the developing dentition. In addition, avoidance of such injury can be dentition. In addition, avoidance of such injury can be facilitated by an incomplete osteotomy with subsequent facilitated by an incomplete osteotomy with subsequent separation occurring during the distraction phase. separation occurring during the distraction phase.

Temporarily fix the distractor into position prior to making Temporarily fix the distractor into position prior to making the osteotomy. Positioning and placement of the device the osteotomy. Positioning and placement of the device after the osteotomy can be difficult because of the after the osteotomy can be difficult because of the mobility of the proximal segment. mobility of the proximal segment.


Make the buccal corticotomy with a reciprocating Make the buccal corticotomy with a reciprocating saw, and "green-stick" fracture the lingual with a saw, and "green-stick" fracture the lingual with a fine osteotome to preserve the inferior alveolar fine osteotome to preserve the inferior alveolar nerve. Complete mobilization is not always nerve. Complete mobilization is not always necessary since the distraction device necessary since the distraction device completes the osteotomy. Warn the patient and completes the osteotomy. Warn the patient and family of the discomfort the patient will feel until family of the discomfort the patient will feel until the fracture is completed. the fracture is completed.

Prior to closure, test the device and clearly mark Prior to closure, test the device and clearly mark for the family the direction (clockwise or for the family the direction (clockwise or counterclockwise) of the driver used to turn the counterclockwise) of the driver used to turn the device. device.

Operative phase – Guidelines for Midfacial Operative phase – Guidelines for Midfacial and Frontofacial Distractionand Frontofacial Distraction - 1 - 1

Place a palatal device to guide the distraction Place a palatal device to guide the distraction vector as part of presurgical preparation. vector as part of presurgical preparation.

Make the osteotomies as with conventional Make the osteotomies as with conventional approaches and complete the mobilization of the approaches and complete the mobilization of the mid face. mid face.

In children in the stage of primary or mixed In children in the stage of primary or mixed dentition, modify the typical LeFort I osteotomy dentition, modify the typical LeFort I osteotomy and place it well above the developing dentition and place it well above the developing dentition at the level of the inferior orbital foramen. at the level of the inferior orbital foramen.

Operative phase – Guidelines for Midfacial Operative phase – Guidelines for Midfacial and Frontofacial Distractionand Frontofacial Distraction - 2 - 2

Midfacial advancements at the LeFort I level with Midfacial advancements at the LeFort I level with currently available internal devices are limited because currently available internal devices are limited because of the difficulty in appropriately orienting the devices in of the difficulty in appropriately orienting the devices in the limited space. The fixation of the device may injure the limited space. The fixation of the device may injure the developing dentition. External multidirectional the developing dentition. External multidirectional devices are preferred as they allow more control over the devices are preferred as they allow more control over the distraction process. distraction process.

Midfacial advancement at the LeFort III level and Midfacial advancement at the LeFort III level and frontofacial advancements can be approached either frontofacial advancements can be approached either with internal or external devices depending on the with internal or external devices depending on the circumstances. Place the internal devices at the level of circumstances. Place the internal devices at the level of the body and arch of the zygoma. External devices the body and arch of the zygoma. External devices require a palatal appliance and additionally traction wires require a palatal appliance and additionally traction wires at the zygoma, nasal root, and supraorbital regions. at the zygoma, nasal root, and supraorbital regions.

Latency PeriodLatency PeriodThis is the initial postoperative phase This is the initial postoperative phase

when fracture healing is allowed to occur when fracture healing is allowed to occur before distracting forces are applied. This before distracting forces are applied. This period typically lasts 5-7 days. In younger period typically lasts 5-7 days. In younger patients (typically, younger than 4-5 patients (typically, younger than 4-5 years), the latency period may be years), the latency period may be significantly shortened or omitted significantly shortened or omitted altogether to prevent early consolidation. altogether to prevent early consolidation.

Distraction Phase - 1Distraction Phase - 1 Bone segments gradually pulled apart using either an internal or Bone segments gradually pulled apart using either an internal or

external device. Three variables must be set:external device. Three variables must be set: the rate of distractionthe rate of distraction the rhythm and/or frequency of distraction and the rhythm and/or frequency of distraction and the total time of distraction. the total time of distraction. The rate of distraction is typically 1.0 mm/d. Some advocate up to The rate of distraction is typically 1.0 mm/d. Some advocate up to

2.0 mm/d in younger children to avoid early consolidation and a 2.0 mm/d in younger children to avoid early consolidation and a slower rate of 0.5 mm/d or 0.25 mm qid in older patients to avoid slower rate of 0.5 mm/d or 0.25 mm qid in older patients to avoid fibrous unions. This can be accomplished either once a day or fibrous unions. This can be accomplished either once a day or divided throughout the day, determining the rhythm or frequency of divided throughout the day, determining the rhythm or frequency of distraction. While the distraction rate is 1.0 mm/d, ideally maintain distraction. While the distraction rate is 1.0 mm/d, ideally maintain the tissues under constant tension by dividing the total daily rate of the tissues under constant tension by dividing the total daily rate of distraction into smaller increments throughout the day to favor distraction into smaller increments throughout the day to favor histogenesis. histogenesis.

Distraction Phase - 2Distraction Phase - 2 The total time of the distraction phase depends on The total time of the distraction phase depends on

achieving the clinical goals; individualize it to each achieving the clinical goals; individualize it to each patient and to the severity of the deformity. Remember patient and to the severity of the deformity. Remember that the total length of bone desired does not necessarily that the total length of bone desired does not necessarily equal the total time of the distraction phase. External equal the total time of the distraction phase. External devices that use pins to transmit the forces frequently devices that use pins to transmit the forces frequently bend, and the distance at the site of the distracting bend, and the distance at the site of the distracting mechanism on the device rarely equals the distance of mechanism on the device rarely equals the distance of the gap at the osteotomy sites. Use clinical guidelines the gap at the osteotomy sites. Use clinical guidelines (eg, position of the chin point, distance from the lateral (eg, position of the chin point, distance from the lateral canthus to the commissure and the mandibular cant) to canthus to the commissure and the mandibular cant) to determine the end point in children with hemifacial determine the end point in children with hemifacial microsomia. microsomia.

Consolidation PhaseConsolidation Phase Once the desired correction is achieved with the Once the desired correction is achieved with the

distraction phase, allow mineralization of the distraction phase, allow mineralization of the immature bone to occur. Lock the distracting immature bone to occur. Lock the distracting appliance into place to maintain stability until the appliance into place to maintain stability until the newly formed bone has sufficient strength. The newly formed bone has sufficient strength. The length of this phase varies depending on the length of this phase varies depending on the circumstances. In general, 6-8 weeks is circumstances. In general, 6-8 weeks is considered adequate. A guideline used by some considered adequate. A guideline used by some centers is 2 days of consolidation to every day of centers is 2 days of consolidation to every day of distraction distraction

Retention PhaseRetention PhaseRemove the device and maintain stability, Remove the device and maintain stability,

typically with the assistance of orthodontic typically with the assistance of orthodontic appliances. In children with hemifacial appliances. In children with hemifacial microsomia, this may require occlusal microsomia, this may require occlusal splints to guide the maxilla into position splints to guide the maxilla into position when the leveling of the mandibular cant when the leveling of the mandibular cant creates a posterior open bite. In children creates a posterior open bite. In children with midfacial deformity, retention may with midfacial deformity, retention may require a face mask with elastic traction for require a face mask with elastic traction for a period of time a period of time

DO of the alveolar ridgeDO of the alveolar ridge Principal problem in Dental Implantation isPrincipal problem in Dental Implantation isLACK OF SUFFICIENT BONE HEIGHT OR WIDTH.LACK OF SUFFICIENT BONE HEIGHT OR WIDTH.Causes include bone loss like periodontal Causes include bone loss like periodontal

disease,pathological disease, trauma and disease,pathological disease, trauma and congenital deformities.congenital deformities.

Insufficient alveolar ridge impedes the use of Insufficient alveolar ridge impedes the use of implants of sufficient length giving a inadequate implants of sufficient length giving a inadequate crown to implant length ratio.crown to implant length ratio.

Options include onlay and interpositional bone Options include onlay and interpositional bone grafts.grafts.

DO of the alveolar ridge (Contd)DO of the alveolar ridge (Contd) DO based on callostasis, the gradual stretching DO based on callostasis, the gradual stretching

of the reparative callus that forms around bone of the reparative callus that forms around bone segments interrupted by osteotomy of segments interrupted by osteotomy of fracture.Stretching is gradual, allowing fracture.Stretching is gradual, allowing maintenance of blood flow.maintenance of blood flow.

Bone regeneration involves two processesBone regeneration involves two processes-Osteogenesis:Callus formation and generation of -Osteogenesis:Callus formation and generation of

new bonenew bone-Histiogenesis:Lengthening of the soft tissues ie -Histiogenesis:Lengthening of the soft tissues ie

mucoperiosteum, nerves and soft tissues.mucoperiosteum, nerves and soft tissues.

ProcedureProcedureConsists ofConsists of Latency period of 5-7 daysLatency period of 5-7 days Distraction rate of 0.5 – 1mm/dayDistraction rate of 0.5 – 1mm/day Consolidation period of 8- 12 weeks.Consolidation period of 8- 12 weeks.???Immediate distraction-dehiscence and exposure ???Immediate distraction-dehiscence and exposure

to oral environment.to oral environment. Magnitude of force more important than frequency Magnitude of force more important than frequency

of application.Minimum and maximum force of application.Minimum and maximum force inducing activation and continued function of the inducing activation and continued function of the cells contributing to osteogenesis is not known.cells contributing to osteogenesis is not known.

Pathophysiology -1Pathophysiology -1 Distraction osteogenesis takes place primarily through Distraction osteogenesis takes place primarily through

intramembranous ossification. Histologic studies identified 4 intramembranous ossification. Histologic studies identified 4 stages that result in the eventual formation of mature bone.stages that result in the eventual formation of mature bone.

Stage I: The intervening gap initially is composed of fibrous Stage I: The intervening gap initially is composed of fibrous

tissue (longitudinally oriented collagen with spindle-shaped tissue (longitudinally oriented collagen with spindle-shaped fibroblasts within a mesenchymal matrix of undifferentiated fibroblasts within a mesenchymal matrix of undifferentiated cells). cells).

Stage II: Slender trabeculae of bone are observed extending Stage II: Slender trabeculae of bone are observed extending from the bony edges. Early bone formation advances along from the bony edges. Early bone formation advances along collagen fibers with osteoblasts on the surface of these early collagen fibers with osteoblasts on the surface of these early bony spicules laying down bone matrix. Histochemically, bony spicules laying down bone matrix. Histochemically, significantly increased levels of alkaline phosphatase, pyruvic significantly increased levels of alkaline phosphatase, pyruvic acid, and lactic acid are noted. acid, and lactic acid are noted.

Pathophysiology -2Pathophysiology -2 Stage III: Remodeling begins with advancing zones of Stage III: Remodeling begins with advancing zones of

bone apposition and resorption and an increase in the bone apposition and resorption and an increase in the number of osteoclasts. number of osteoclasts.

Stage IV: Early compact cortical bone is formed adjacent Stage IV: Early compact cortical bone is formed adjacent to the mature bone of the sectioned bone ends, with to the mature bone of the sectioned bone ends, with increasingly less longitudinally oriented bony spicules; increasingly less longitudinally oriented bony spicules; this resembles the normal architecture. this resembles the normal architecture.

By 8 months, the intervening bone within the distraction By 8 months, the intervening bone within the distraction zone achieves 90% of the normal bony architecture. It is zone achieves 90% of the normal bony architecture. It is believed that the architecture is maintained and that the believed that the architecture is maintained and that the bone responds to normally applied functional loads. bone responds to normally applied functional loads.

Alveolar DO – Fig 1Alveolar DO – Fig 1


Alveolar DO –Fig 3Alveolar DO –Fig 3

Alveolar DO- Fig 4Alveolar DO- Fig 4











AppliancesAppliances External devices. Anchored by transcutaneous External devices. Anchored by transcutaneous

pins used to achieve transport and stabilization of pins used to achieve transport and stabilization of the skeletal fragments. (Unacceptable to most the skeletal fragments. (Unacceptable to most patients).patients).

Internal devices -acceptable, application to a wide Internal devices -acceptable, application to a wide range of anatomical locations,no skin range of anatomical locations,no skin incision,limited risk to the facial nerve.incision,limited risk to the facial nerve.

Internal-juxtaosseous and intraosseous.Internal-juxtaosseous and intraosseous. Juxtaosseous-placed on buccal aspectJuxtaosseous-placed on buccal aspect Intraosseous-run through the transport segment in Intraosseous-run through the transport segment in

the direction of the distraction.the direction of the distraction.

ComplicationsComplicationsArising during surgery, generally related to Arising during surgery, generally related to

osteotomy and distractor placementosteotomy and distractor placementArising during distraction, including Arising during distraction, including

incorrect direction of distraction and soft incorrect direction of distraction and soft tissue complicationstissue complications

Arising after distraction, due to defective Arising after distraction, due to defective bone formation.bone formation.

A peep into the futureA peep into the futureWhat should be the minimum height What should be the minimum height

requirement for DO?requirement for DO?Joint use of bone graft and DO.Joint use of bone graft and DO.How long after bone graft should DO How long after bone graft should DO

commence? 3 months or a year? commence? 3 months or a year?

ConclusionConclusion Alveolar DO is a technique which involves Alveolar DO is a technique which involves

freeing a bone segment (the transport segment) freeing a bone segment (the transport segment) from the basal bone, but retaining attachment from the basal bone, but retaining attachment via the lingual periosteum. It is preferable to via the lingual periosteum. It is preferable to bone grafting for increasing bone height and bone grafting for increasing bone height and width.The regenerated bone has been found to width.The regenerated bone has been found to be highly resistant to resorption and capable of be highly resistant to resorption and capable of supporting heavy loads and enables the supporting heavy loads and enables the placement of implants with good esthetics.placement of implants with good esthetics.

Distraction osteogenesis (5)

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