Distraction histogenesis: A traction force applied to bony segments also creates tension in the surrounding soft tissues, initiating a sequence of adaptive changes termed as distraction hisogenesis
Bone lengthening by distraction osteogenesis dates back to Alessandro Codiwilla, who in 1905 published the first report of surgical limb lengthening. He used an oblique osteotomy and external traction pins to lengthen limbs which were originally shortened by congenital deformity or trauma. The basic method of externally distracting a surgically-created osteotomy did not change much for the next 70 years. During the first half of the century, this technique did not gain clinical acceptance because every surgeon attempting leg lengthening procedures encountered serious complications such as infections, overstretching, poor blood supply, and inadequate fixation.
In 1950’s, Illizarov, a Russian orthopedic surgeon defined a number of biological and mechanical factors that play a role in the process of new bone formation and began the modern era of DO, applying it primarily to lengthen limbs. He gave the law of tension stress that if steady traction is applied to bone fragments after corticotomy or osteotomy, the bone can be lengthened by formation of new bone at the surgical site by callotosis. In particular, he explained the significance of rhythm and rate of distraction, preservation of the periosteum, bone marrow and vascularity, and stable fixation to successful bone lengthening with minimal complications.
McCarthy was the first who introduced the application of craniofacial distraction in mandible
Maxillary distraction was reported in 1993 by Rachmiel et al who performed midface gradual advancment on five sheep. Block et al demonstrated anterior maxillary advancement using tooth borne device in Dog
Polley et al used an externally fixed cranial halo frame to distract the midface
The basic technique of DO involves five sequential steps
A corticotomy is made preserving the local blood supply to both the periosteum and medullary canal. However, greater blood supply in the facial skeleton prefer osteotomy of the jaws which is more predictable and less uncomfortable for the patients
The distraction device is inserted so that the two bony ends are stable during the first five days. This period is called the latency period during which initial fracture healing and callus formation occurs.
If distraction begun too early, the result is decreased bone formation often with cartilaginous elements present and decreased mechanical strength of new bone. If it is too late (after the hard callus formation), the distraction device may be unable to further separate the bone.
There are two important variables in the activation i.e. rate or amount of distraction per day and rhythm that is how frequently the device is activated.
Ideally, Distraction of the bony ends is initiated at a rate of 1 mm/day at a rhythm of 0.25 mm every 6 hours. In majority of maxillofacial cases the most common protocol is 0.5 mm twice a day,
New bone is usually visible in the distraction gap by the third week. Ossification occurs at the edges and then progresses toward the center of the stretched callus.
The distraction device is left in place while the regenerate bone matures and remodels. The distractor must be rigid enough to prevent movement of bone during this period of healing. If movement occurs, either from inadequate fixation or premature removal of the appliance, a malunion or fibrous non union may occur.
Ideally the consolidation period should coincide with the time required for complete mineralization of the bone
“A biological process of new bone formation between
the surfaces of osteotomized bone segments that are
separated gradually by incremental traction”
Distraction Histogenesis :
– Adaptive regenerative changes in surrounding soft tissues
Alessandro Codiwilla (1905)
– First report of surgical limb lengthening
– Oblique osteotomy and external traction pins
– Complications: infections, overstretching, poor blood
supply and inadequate fixation
G.A. Ilizarov (1950’s)
– Lengthening limbs through gradual distraction of fracture
– Rhythm and rate of distraction
– Minimal complications
– DO to lengthen congenitally hypoplastic mandible
• Rachmiel et al (1993) and Blocks et al (1995)
– Maxillary distraction
• Polley et al (1995)
– Midface distraction with externally fixed cranial halo frame
• Divides the bone into two segments
• Triggers process of bone repair
• Period from bone division to onset of distraction
• Inflammation and soft callus formation of the fractured bone
• Soft callus formation begins 3-7 days and lasts 2-3 weeks
• Latency period = 5-7 days
• Characterized by the application of traction forces to osteotomized
• Rate : 1 mm/day
• Rhythm : 0.25 mm every 6 hours
0.5 mm twice a day
• Duration : 1-3 weeks
Cessation of traction forces to removal of distractor
• Newly formed bone mineralizes and increases in bone density
Duration: 3- 4 months
• Removal of distractor to application of functional
• Formation of lamellar bone
• For V shape mandible
• Severe mandibular crowding
• Brodie’s syndrome
• To avoid inderdental stripping or extractions