The principle of distraction osteogenesis (Ilizarov method) is based on the law of tension stress, which states that slow controlled traction on living tissues creates a state of sustained tension that stimulates bone generation. The recommended rate and rhythm of distraction for optimal bone regeneration is:
- A 1 mm/day in a single daily increment
- B 1 mm/day divided into 4 increments of 0.25 mm every 6 hours ✓
- C 2 mm/day in 2 daily increments
- D 0.5 mm/day in a single daily increment
Correct answer: B. 1 mm/day divided into 4 increments of 0.25 mm every 6 hours
Explanation
Ilizarov demonstrated that optimal bone regeneration requires a rate of 1 mm/day divided into frequent small increments (ideally 4 times daily, 0.25 mm each), which provides a more continuous tensile stimulus than single large daily adjustments. Faster distraction (>1.5 mm/day) produces fibrous non-union; slower rates (<0.5 mm/day) may allow premature consolidation. A latency period of 7–10 days after corticotomy precedes distraction to allow callus formation.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.