DISTRACTION OSTEOGENESIS
- DICTIONARY -

Activation pin (screw) – a structural distraction device element that rotates the distraction rod.

Angular distractor – a structural distraction device element that consists of a distraction rod with two pivotable connectors at both ends.

Bi-directional distraction device – a device capable of independent distraction in two directions, i.e., it can distract both vertically and horizontally following either a single- or double-level osteotomy. In addition, an adjustment in the angular relationship between the two distraction vectors is possible during lengthening.

Bifocal distraction-compression osteosynthesis – a distraction osteogenesis technique that involves two sites of distraction or compression, i.e., bifocal lengthening following double-level osteotomy (distraction osteosynthesis) or bone transport with distraction and docking sites (distraction-compression osteosynthesis).

Bone-borne distraction device – a device that is attached only to bone as a means of direct skeletal fixation.

Bone transport – a distraction osteogenesis technique for treating bone defects; involves gradual movement of a vascularized bony segment or "transport disk" previously separated from the residual bone segment adjacent to the defect. New bone is formed during movement of the transport disk in the distraction site with simultaneous closing of the bony defect followed by compression osteosynthesis at the docking site.

Callotasis – a distraction osteogenesis technique that involves gradual stretching of the reparative callus, which forms around bone segments interrupted by osteotomy or fracture.

Callus – the tissue that forms between and around fractured bone segments to maintain structural integrity and facilitate bone regeneration.

Chondrodiatasis – a physeal distraction technique that involves a small amount (~ 0.5 mm per day) of growth plate stretching without prior fracture or osteotomy. This stretching intensifies the biosynthetic activity of cartilage cells, resulting in accelerated osteogenesis.

Closing wedge hinge – a hinge with the axis of rotation located at the osteotomy level on the convex side of the deformity. When using this type of hinge, the length of the distraction gap will decrease, resulting in compression of the newly formed tissues.

Consolidation (fixation) period – the time required for remodeling of the regenerate tissue, or the time between removal of traction forces and removal of the distraction device.

Corticotomy – a bone division technique in which only the bony cortex is surgically cut, thereby maximally preserving periosteum, endosteum, and bone marrow.

Cross-wire fixation – a method of long bone fixation using a circular external fixator with a pair of thin Kirschner wires oriented at 90 degrees to each other and perpendicular to the long axis of the bone.

Device orientation – the direction in which the distraction device is positioned, usually relative to the anatomical axis of the bone segments to be distracted.

Diaphysis – the shaft of a long bone.

Distraction – the separation of two bone segments.

Distraction axis – the direction in which the distal bone segment is distracted.

Distraction-compression osteosynthesis – distraction osteogenesis techniques that involve gradual movement of bone segments away from (distraction) or toward each other (compression).

Distraction device (appliance) – a mechanism that allows gradual incremental movement of bone segments away from each other.

Distraction epiphysiolysis – a physeal distraction technique with a large amount (~ 1.0 mm to 1.5 mm per day) of growth plate stretching. The increased tension at the growth plate produces a fracture, which is followed by separation of the epiphysis from the metaphysis, leading to replacement of the growth plate by trabecular bone.

Distraction histogenesis – a sequence of adaptive changes in the soft tissues, initiated as a result of the tension created by distraction of bone segments.

Distraction osteogenesis – a biologic process of new bone formation between vascularized margins of bone segments that are gradually separated by incremental traction.

Distraction parameters – biological and biomechanical variables that affect the quality and quantity of bone formed during osteodistraction.

Distraction period – the time when gradual traction is applied to bone segments and new tissue (regenerate tissue) is formed.

Distraction protocol – the sequence and duration of events during osteodistraction.

Distraction rate – the total amount of distraction performed per day.

Distraction regenerate – the tissue that forms between gradually separated bone segments; is initially fibrocartilagenous, but is quickly mineralized.

Distraction rhythm – the number of increments per day into which the rate of distraction is divided.

Distraction vector – the final direction and magnitude of traction forces during distraction.

Docking site – the site at which the transport disk touches after being moved through the bone defect; compression is usually applied at the docking site.

Double-hinge activator – an activation pin connected to the distraction rod by a two-dimensional hinge.

Double-level osteotomy – the separation of one bone into three segments at two levels.

Dynamic axial fixator – a distraction device that allows controlled axial micromotion of bone segments during distraction and consolidation periods.

Epiphysis – the part of a long bone that develops from a center of ossification distinct from the bone shaft.

External skeletal fixation – stabilization of fractured bone segments by pins or screws drilled through the overlying skin and connected by an external bar.

Extraoral distraction – a distraction procedure in which the distraction device is located extraorally, usually by direct skeletal fixation.

Extraoral (external) distraction device – a device that is located outside the oral cavity. The bone segments are usually attached to percutaneous pins connected externally to device fixation clamps.

Extrinsic biomechanical parameters – factors that affect the mechanical properties of the distraction appliance and stability of bone segment fixation. These factors include the number, length, and diameter of fixation pins; the rigidity of the distraction device; and material properties of the device.

Fibrous interzone – a poorly mineralized, radiolucent fibrous region located in the middle of the distraction gap. This zone functions as the center of fibrous tissue formation and consists of longitudinally oriented parallel bundles of collagen with fibroblast-like and undifferentiated mesenchymal cells.

Fixation clamp – a structural distraction device element that connects bone-anchoring elements to the distractor.

Floating bone concept – a distraction osteogenesis technique that involves bone lengthening along the anatomical axis followed by acute manipulation of the distraction regenerate to reposition the distracted bone segments (i.e., mandibular lengthening followed by acute openbite correction).

Fracture – a loss of continuity and mechanical integrity of a bone.

Fracture callus – the tissue that forms between and around fractured bone segments to maintain structural integrity and facilitate bone regeneration.

Guided tissue regeneration – a bone generation technique, in which barrier membranes are used to prevent the ingrowth of faster growing, less differentiated
tissues.

Hinge – a structural distraction device element that allows free movement around its center of rotation.

Host bone – bone present prior to initiating osteodistraction.

Hybrid distraction device – a device that is attached both to the teeth and bone, thereby providing both direct and indirect skeletal fixation.

Hypertrophic regenerate – a regenerate characterized by a diameter that is significantly greater than the host bone segments.

Hypotrophic regenerate – a regenerate characterized by a diameter that is significantly smaller than the host bone segments.

Inferior distraction vector angle – the angle formed between the mandibular plane and the distraction vector.

Interdental osteotomy – bone division between two teeth.

Intermaxillary elastic fixation – a method of facial bone fixation using elastics worn between attachments on the maxillary and mandibular arches for the purpose of maintaining occlusal relationships.

Intraoral distraction – a distraction procedure in which the distraction device is located completely within the oral cavity; it can be either bone-borne, tooth-borne, or hybrid.

Intraoral (internal) distraction device – a device that is located inside the oral cavity. The device can be attached to the bone (bone-borne), to the teeth (tooth-borne), or simultaneously to the teeth and bone (hybrid).

Intrinsic biomechanical parameters – factors that affect the quality and quantity of the forming distraction regenerate. They include the geometric shape, cross-sectional area, and density of the distracted bone segments; the length of the distraction regenerate; as well as the tension developing within the soft tissue
envelope, which includes muscles, ligaments, and fascia.

Latency (waiting) period – the time frame between bone division and the initiation of traction forces, or the period required for reparative callus formation.

Locking plate – same as fixation clamp.

Longitudinal distraction – distraction along the anatomical axis of a bone.

Mandibular arch angle – the angle formed by the intersection of the right and left mandibular bodies.

Metaphysis – the conical section of bone between the epiphysis and diaphysis of a long bone.

Monofocal distraction-compression osteosynthesis – a distraction osteogenesis technique that involves one site of distraction or compression, i.e., monofocal lengthening following single-level osteotomy (distraction
osteosynthesis), compression of a nonunion (compression osteosynthesis), or compression of a nonunion followed by lengthening (compression-distraction osteosynthesis).

Multi-directional distraction device – a device capable of independent distraction in two directions as well as gradual transverse and angular adjustments.

Normotrophic regenerate – a regenerate characterized by a diameter that is similar to the host bone segments.

Opening wedge hinge – a hinge with the axis of rotation located at the osteotomy level on the concave side of the deformity. This type of hinge is used either solely for angular correction (the axis of hinge rotation is placed at the bone margin) or in combination with lengthening (the axis of hinge rotation is placed away from the
bone margin).

Osteoclasis – intentional fracture of a bone.

Osteodistraction – same as distraction.

Osteogenesis – the formation of bone.

Osteotomy – a surgical technique to divide a bone into two or more segments.

Partial corticotomy – a bone division technique where two-thirds of the bony cortex is divided with a narrow osteotome followed by completion of bone separation by rotational osteoclasis.

Physeal distraction – a distraction osteogenesis technique that involves gradual stretching of the bone growth plate (physis).

Physis – bone growth plate.

Premature consolidation – ossification of the fibrous interzone during the distraction period prior to completing distraction.

Primary osteon – a tiny bone trabecula with an actively growing apex, which remains open during the distraction period. Two zones of these longitudinally oriented cylindrical primary osteons are located on either side of the fibrous interzone and grow toward each other.

Regenerate maturation – the completion of mineralization and remodeling of the regenerate tissue.

Rigid fixation system – a distraction device that does not allow micromotion of bone segments during distraction or consolidation.

Rotating clamp – a fixation clamp on the distraction device, the position of which can be angularly adjusted relative to the distractor.

Rotational osteoclasis – intentional fracture of a bone by rotating the proximal and distal bone ends in opposite directions.

RPE – rapid palatal expander; a device traditionally used to separate the maxilla at the midpalatal suture.

Semi-rigid fixation system – a distraction device that allows uncontrolled micromotion of bone segments during distraction and consolidation periods.

Single-level osteotomy – the separation of one bone into two segments at one level.

Sliding clamp – a fixation clamp on the distraction device, the position of which can be linearly adjusted relative to the distractor.

Superior distraction vector angle – the angle between the maxillary occlusal plane and the distraction vector.

Tooth-borne distraction device – a device that is attached only to the teeth as a means of indirect skeletal fixation.

Translational hinge – a hinge with the axis of rotation located anterior or posterior to the osteotomy level on the concave side of the deformity. This hinge allows both angular movement and translation of the anatomical axis of the bone segments to occur simultaneously in the desired direction.

Transport disk – a vascularized bone segment separated from the residual bone segment in order to be gradually advanced through the defect.

Transverse distraction – distraction perpendicular to the anatomical axis of a bone.

Trifocal distraction-compression osteosynthesis – a distraction osteogenesis technique that involves three sites of distraction or compression, i.e., trifocal lengthening following triple-level osteotomy (distraction osteosynthesis) or transport of two bone disks toward the midline of an osseous defect (distraction-compression osteosynthesis).

Uni-directional distraction device – a device capable of distraction in one direction only, either horizontal, vertical, or transverse.

Universal hinge – a structural distraction device element that allows three-dimensional movement of bone segments.

Zone of bone remodeling – area of distraction regenerate where the newly formed bone begins to remodel.

Zone of extending bone formation – area of distraction regenerate where new bone trabeculae form.

Zone of mature bone – area of distraction regenerate where the newly formed bone has remodeled and is undistinguishable from the host bone.

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