Distraction Osteogenesis
On this page
Direct answer
Distraction osteogenesis makes the body manufacture its own bone: an osteotomy heals for a latency of about five to seven days, the fragments are then separated slowly — classically 1 mm per day, in Ilizarov's rhythm of quarter-millimetre steps four times daily — and the regenerate matures over a consolidation phase of some two to three months. Codivilla performed the first limb lengthening in 1905 and Ilizarov systematised the biology under the tension-stress effect; Snyder demonstrated it in the mandible in 1973 and McCarthy brought it to the human craniofacial skeleton in 1992, where it now lengthens the deficient mandible, advances the maxilla and reconstructs segmental defects by transport.
What you must remember
- Three phases with parameters: latency of roughly 5-7 days; distraction at about 1 mm per day — slower risks premature consolidation, faster risks fibrous union — and consolidation of 6-12 weeks until the regenerate bears load.
- Ilizarov's tension-stress effect: gradual traction stimulates regeneration of bone and the surrounding soft tissue matrix together — the crucial difference from conventional osteotomy, whose limit is stretched soft tissue, not bone.
- Distraction histogenesis: simultaneous lengthening of muscle, nerve, vessels and mucosa — why distraction achieves advancements orthognathic surgery cannot hold, classically in cleft maxillary hypoplasia and severe mandibular deficiency.
- Devices: extraoral pin-based (powerful vectors, visible scars), intraoral tooth-borne or bone-borne (teeth bear the load in tooth-borne designs), unidirectional, bidirectional and vector-changing distractors.
- Applications: mandibular lengthening in micrognathia and hemifacial microsomia (Pruzansky I and IIA distract well; IIB and III often need costochondral grafting); Pierre Robin tongue-based airway obstruction as an alternative to tracheostomy; cleft maxillary advancement; alveolar augmentation.
- Transport distraction: a transport disc of bone is moved across a defect, trailing regenerate that fills the gap — a graftless reconstruction of segmental mandibular defects.
- Complications: device failure, pin-tract infection, premature consolidation, fibrous or non-union, tooth and nerve injury (the inferior alveolar nerve tolerates slow distraction well), relapse and scarring.
- Relapse is reduced, not abolished: overcorrection in children and prolonged device retention are standard countermeasures.
A worked case
A 3-year-old with Pierre Robin sequence has gross mandibular deficiency, glossoptosis and obstructive episodes failing conservative positioning. Walk the treatment. Airway first: polysomnography quantifies obstruction; tongue-lip adhesion is one option, but mandibular distraction addresses the skeletal cause directly. Planning: three-dimensional CT maps the mandible and tooth buds, the osteotomy avoiding them and the canal. Surgery: oblique subsigmoid osteotomies without full periosteal stripping (periosteum feeds the regenerate), distractors fixed, tested and returned to zero. Protocol: latency about 5 days, then 1-1.5 mm per day in divided activations, monitored clinically. Consolidation about 8-12 weeks, then device removal. Follow-up for years: mandibular growth, occlusion and relapse surveillance, because distraction in the very young does not guarantee normal later growth. The accompanying questions — why the nerve tolerates slow stretch (perineural adaptation under tension-stress), and why not advance conventionally (a 3-year-old's soft tissue envelope cannot hold a large advancement) — are where the marks separate.
Where students slip
Parameter mixing heads the errors: latency, rate and rhythm must each be named with numbers — a candidate who writes "distract 3 mm per week" without knowing the daily rate logic (capillary ingrowth follows the distraction; too fast outruns the blood supply into fibrous union) has recited without understanding. The second slip is forgetting the soft tissue: the entire advantage of distraction over one-step advancement is distraction histogenesis, and the answer that mentions only bone misses the concept. The third is application confusion: offering distraction for TMJ ankylosis release itself (it is an adjunct for the hypoplastic ramus after release, and increasingly used, but the ankylosis operation remains resection with interposition) or for an adult with a mild Class II deformity (orthognathic surgery is quicker, and the examiner wants that judgement).
Frequently asked questions
What are the three phases of distraction osteogenesis with their durations?
Latency of about 5-7 days after osteotomy, active distraction at roughly 1 mm per day, and consolidation for about 6-12 weeks until the regenerate mineralises sufficiently.
What is the tension-stress principle of Ilizarov?
Gradual, controlled traction on living tissues stimulates regeneration of bone and simultaneous histogenesis of the surrounding soft tissues — muscle, vessels, nerve and skin — not merely stretching.
What complication results from distracting too slowly or too fast?
Too slow (or an over-long latency) allows premature consolidation of the regenerate; too fast outruns vascular ingrowth, producing fibrous union or non-union.
Who performed the first craniofacial distraction and in what year?
McCarthy in 1992, lengthening the human mandible — after Snyder's 1973 experimental mandibular distraction in dogs and decades of Ilizarov's orthopaedic work.
What is transport distraction?
Moving a transport segment of viable bone gradually across a defect, leaving newly formed regenerate trailing in its path — a graftless reconstruction of segmental mandibular defects.
Why does distraction suit the cleft maxilla better than conventional advancement?
Large conventional advancements in scarred cleft maxillae relapse under soft tissue pull; distraction advances bone while the soft tissue matrix grows with it, markedly reducing relapse.