CRANIOFACIAL DISTRACTION OSTEOGENESIS SAMCHUKOV PDF
Posted On June 29, 2020
Craniofacial Distraction Osteogenesis by Alexander M. Cherkashin, technique mastered by the lead author, Mikhail L. Samchukov, MD. Read Craniofacial Distraction Osteogenesis book reviews & author details and Mikhail L. Samchukov, MD, Associate Director of Ilizarov Research, Texas. Jason B. Cope, Mikhail L. Samchukov, Alexander M. Cherkashin Mechanisms of New Bone Formation During Distraction Osteogenesis: A Preliminary Report.
Limb lengthening by distraction osteogenesis was first described in The technique did not gain wide acceptance until Gavril Ilizarov identified the physiologic and mechanical factors governing successful regeneration of bone formation.
Distraction osteogenesis is a samchukovv variation of more traditional orthognathic surgical procedure for the correction of dentofacial deformities. It is most commonly used for the correction of more severe deformities and syndromes of both the maxilla sacmhukov the mandible and can also be used in children at ages previously untreatable.
The basic technique includes surgical fracture of deformed bone, insertion of device, days rest, and gradual separation of bony segments by subsequent activation at the rate of 1 mm per day, followed by an weeks consolidation phase.
This allows surgeons, the lengthening and reshaping of deformed bone. The aim of this paper is to review the principle, technical considerations, applications and limitations of distraction osteogenesis.
Craniofacial Distraction Osteogenesis
The application of osteodistraction offers novel solutions for surgical-orthodontic management of developmental anomalies of the craniofacial skeleton as bone may be molded into different shapes along with the soft tissue component gradually thereby resulting in less relapse. Despite the fact that conventional orthognathic surgery and craniofacial reconstruction have experienced widespread success but in recent years the practice of surgery has been altered by an increased understanding and manipulation of biological systems; for example, induction of the native tissue.
Distraction osteogenesis of the craniofacial skeleton serves as an example of this most recent paradigm shift. It is a process of new bone formation between the surfaces of bone segments gradually separated by incremental traction.
The mechanical forces are directed predominantly away from the site, and the technique takes advantage of the regenerative capacity of bone by creating and maintaining an active area of bone formation in distractiln surgically created gap. The disgraction is lengthened along crsniofacial its envelop. There have been reports of this craniofackal of distraction being used as early as inby Codvilla. Later, Stader in used mandibular external fixator. However, it was Ilizarov in s, who established the scientific basis of this concept and showed that with this procedure lengthening of long bones without using a graft material was possible.
Molina and Ortiz-Monasterio were the first to use bidirectional osteodistraction in the mandible. Mandibular distraction in humans using an extraoral distractor in patients with hemifacial microsomias was first reported in [ 6 ].
Gradual traction of the tissues creates stress that activates osteigenesis growth and regeneration. The shape and mass of the bone are influenced by the mechanical load and blood supply. Depending upon the place of tensional stress induction technique into Physeal Distraction and Callotasis. Physeal distraction is further classified into Distraction Epiphysiolysis and Chondrodiatasis. On the basis of distraction device used as Extraoral, Subcutaneous and Intraoral devices.
Intraoral devices were further classified as a Submucosal and b Extramucosal devices. Bone formation in general may be through cartilaginous intermediate endochondral ossification or from recruitment and differentiation of primitive mesenchymal cells membranous ossification seen in distraction osteogenesis [ Table 1 ].
Molecular events and mechanism of bone formation in distraction osteogenesis in humans.
Unfavourable results with distraction in craniofacial skeleton
As distraction healing is a highly dynamic cellular process, tensile strains are the leading stimuli for bone regeneration. Mechanical signals play an integral wamchukov in bone hemostasis. It is generally suggested that distraction forces leading to cellular deformation are signalled to the cellular genome through mechanotransduction.
Nuclear proto-oncogene c-fos and c-jun are found to be unregulated at early stages of distraction and are related to the mechanotransduction and embryonic bone development. Mechanotransduction is an essential cellular mechanism for bone adaptation to mechanical samchukovv. Bone diztraction can samchuokv physical force signals, transform these physical stimuli into biochemical signals, integrate these signals into cellular responses of osteoblasts and osteoclasts, and then finally lead to appropriate changes in the architecture of bone.
It is the transduction of mechanical force applied to the tissue into a local mechanical signal perceived by a bone cell. Duncan and Turner[ 12 ] concluded that there are four types of mechanoresponsive structures in cells to sense a load, including integrins, the cytoskeleton, G-proteins and ion channels.
Gi-proteins were confirmed to co-localize with stretch-activated calcium channel. Recently, Annexin V, a calcium-binding protein, has been identified to be involved in the fluid flow activation of calcium channels. It is the transduction of a local mechanical signal into biochemical signal cascades altering gene expression or protein activation.
Most studies demonstrate that mechanical stress stimulates osteoblasts to release prostaglandin E2 PGE2 [ 14 ] and adenosine triphosphate[ 15 ] and to secret nitric oxide. Is transmission of signals from the sensor cells to effector cells, which actually form or remove bone. ERK is considered to be a potential mediator that acts as a signaling convergence point and its activation is a prominent load-induced response of osteoblasts. More intriguingly, mechanical stimulation up-regulated the production of insulin-like growth factor IGF -I.
Moreover, physiological loading was shown to induce the activation of the estrogen receptor. In osteoblasts, physiological levels of strain were shown to result in an altered expression of bone-specific proteins, such as alkaline phosphatase, collagen I, osteopontin, osteocalcin, Runx2 and osterix. Aside from early response gene c-fos, early growth response factor 1, heme oxygenase 1 and basic fibroblast growth factor can also be induced by mechanical strain.
These activities lead to the onset of mineralization, proliferation and differentiation. Thus, tension causes chondroblast to express type I instead of type II collagen. Danis[ 23 ] hypothesized that distraction osteogenesis of long bone relies on two local factors: Progressive return to aerobic conditions by neoangiogenesis assures the permanency of the new osseous structures.
After performing the osteotomy, there is disruption of cortex followed by migration of inflammatory cells and samchhukov of hematoma and procallus.
As distraction process progress, there is marked vascular response including increased angiogenic mediator expression and blood vessel formation. Collagen fibers oriented along the axis or vector of distraction forces. This is followed by initial mineralization which appears days of distraction. Distraction forces applied to bone also create tension in the surrounding soft tissues, initiating a sequence samchkov adaptive changes in different tissues, including: Skin, blood vessels, nerves, muscle, ligament, tendon, and cartilage.
Long-term success of distraction osteogenesis depends on the ability of the surrounding soft tissues sakchukov tolerate distraction forces and to adapt to the resulting increase in skeletal length and volume. A proliferative response may craniifacial to improved long-term stability of mandibular expansion by distraction osteogenesis.
Physical and biological parameters affecting the success of distraction osteogenesis include the macro- and microscopic bone anatomy, the direction and amount of the applied distraction forces, and the regenerative capacity of the tissues involved. Force transduction via adjacent structures joints, ligaments, muscles, and soft tissue influences the regeneration of the tissue between the bone fragments by modulating the stress produced fistraction the callus, which is plastic and malleable.
Controlled elongation of the callus results in increase in length of bone without significant disruption of healing process followed by adequate period of immobilization resulting in calcified new bone with normal architecture. Various factors which regulate bone formation distrwction Rh-BMP-2 osteogenesie been shown to accelerate bone formation in mandibular samcuhkov tibial distraction models.
Recent experimental work implications to promote regeneration, craniofacisl and maturation in distraction osteogenesis. Chitosan is a polysaccharide which enhance bone formation and aid in the differentiation of osteoprogenitor cells. BMPs are potent inducers osteogenssis osteogenesis both during embryological bone formation and in fracture osteogeneais. Among the members of the large BMP family, BMP-2, -4, and -7 have been shown to be especially important for osteogenesis.
After a fracture, expression of BMP-2, -4, and -7 is quickly induced in cells close to the periosteum and appears to be limited mostly to immature cells and its expression increases after distraction is started. They found that the BMP-2 signal was greatest at the stage of intramembranous formation of bone and early chondrogenesis, suggesting that BMP-2 mediates the differentiation of mesenchymal cells into osteoblasts and chondroblasts.
Immunohistochemical craniofackal showed that BMP-2 and PCNA both appeared initially at the edge of the osteogenesis, distractin tended to disappear after craiofacial days. They suggested that suggest that BMP-2 plays an important part in the induction of bone formation during distraction osteogenesis.
Conversely, rh-BMP-2 was effective in enhancing consolidation when applied as solid or liquid phase at day 0 and at the end of distraction.
Possible explanation given by them to this fact is that endogenous BMP-7 is far less expressed than endogenous BMP-2 during the distraction phase. Animal studies by Karp et al. The five zones are: The distradtion transitional areas are the two areas of vasculogenesis and the two areas of mineralization fronts. The central zone is the most cellular and most blastema-like. The transitional area of mineralization front shows nascent trabeculae in perfect alignment with the line of tensile force.
At 2 months after distraction, the initial gap was filled with mineralized bone and showed remodeling areas, mainly in dense cortical zones. Adequate exposure of the site is performed; distractor is fixed in desired position and vector by one or two screw on either side of marked osteotomy line on the bone.
Distractor is then craniifacial and the osteotomy completed through oxteogenesis through. Distractor is then repositioned back on to the predetermined place. Osteotomy is checked by activating the distractor for unhindered separation of bone. Distractor is deactivated leaving a small distractoon between osteotomized segments and closure of flap is then performed. Distractor is finally activated for few turns depending upon size of the bone.
Osteotomy is the surgical separation of a bone in to segments. Osteotomy of bone results in a loss of continuity and the mechanical integrity of the bone. This process stimulates the healing process, which triggers the grouping of osteoprogenitor cells, continues production of bone cells and creates an environment that is distractjon for bone conduction.
The formation of new bone starts at the fracture ends.
Unfavourable results with distraction in craniofacial skeleton
The Incision to access the bone must be conservative in length, with minimal dissection of the periosteum to ensure good blood supply close to the osteotomy site.
Osteotomy must be performed with copious irrigation to prevent heating. After distractor is fixed, osteotomy is craniofafial and distractor is activated 2 mm. In rabbit tibias, Richards et al.
It has been speculated that an increase in shear forces may provide greater stimulation of osteoblasts and ossification centers. The duration of latency is controversial for facial bone distraction osteogenesis. An experimental study by Glowacki et al. Other animals studies supporting this idea, showed dustraction bone strength and callus formation between a latency duration of 0 and 7 days in the sheep model.
Craniofacial Distraction Osteogenesis – Mikhail L. Samchukov – Google Books
A shorter latency period was suggested to be sufficient for the early stage of healing process because the craniofacial bones have a rich vascular supply. Based on the above inconsistencies, the suggested optimal duration is between 5 and 7 days. During this period histologically initial clot formed is converted at 3 days into granulation tissue which becomes increasingly fibrous due to the presence of collagen and increasingly vascular through the appearance of new capillaries. This phase usually lasts weeks, and the traction modifies the normal development of the regeneration process.
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