The Ilizarov principle of 'tension stress' states that controlled, gradual distraction at the rate of 1 mm/day in 4 increments (0.25 mm × 4/day) stimulates:

• A Fibrocartilage formation at the distraction gap followed by endochondral ossification
• B Periosteal callus formation through enchondral ossification identical to fracture healing
• C Intramembranous-like bone formation (membranous ossification) at the distraction site with formation of regenerate bone ✓
• D Mechanical stimulation of adjacent bone grafts placed at the osteotomy site

Explanation

The Ilizarov tension-stress effect demonstrates that gradual, controlled mechanical tension at the rate of 1 mm/day (divided into 4 increments of 0.25 mm) stimulates regenerate bone formation through intramembranous-like ossification — bone columns form centripetally from the periosteal/endosteal surfaces toward a central fibrovascular zone, without a cartilaginous intermediate (unlike fracture healing). The biologic prerequisite is an intact periosteum and medullary blood supply (hence the corticotomy technique preserves these). This regenerate is radiologically visible as a growth zone between two cortical fronts.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.