June 20, 2024

Distraction Osteogenesis is based on the law of distraction neohistogenesis which is ” when tissue is fixed with a stable device subjected to planar distraction forces after an atraumatic corticotomy, new tissue formation occurs in the presence of intact vascularity and maintained function.

New tissue formation: Not only new bone between osteotomized bony cut ends but also a new muscle, tendon, connective tissue, blood vessels, nerves, skin, and integuments

The principle of Distraction osteogenesis is given by Gavriil Abramovich Ilizarov (15 June 1921 – 24 July 1992) 

So Ilizarov’s technique works in the above-mentioned principles

Ilizarov apparatus
Ilizarov apparatus

7-Rules of Distraction Osteogenesis (Ilizarov techniques)

Principles of Distraction Osteogenesis are summarized as:

Rule 1: Stability of fixation

  • Painfree mobilization and weight-bearing are essential
  • Stability can be increased by more fixation pins, more connection of pins to circular rings having small diameter rings
  • If reduced stability, regenerate formation will be poor, patchy, and nonhomogenous or absent

Rule 2: Atraumatic corticotomy

  • Corticotomy:- Formation of physics anywhere in bone after skeletal maturity
  • Performed after minimal invasive procedure (5 mm) incision
  • Cut only the hard part of the bone and preserve the periosteum
  • In the end: Bony fragment shouldn’t be displaced and must remain in contact with no separation of bony ends

Rule 3: Latency Period

  • 5-7 days of latency is required before starting distraction at corticotomy site
  • The younger patient requires less time: 4-5 days
  • The older patient requires more time: 10-15 days
  • Soft tissue good: Decrease latency
  • Percutaneous corticotomy ( By drill holes): Decrease latency

Rule 4: Rate of distraction

  • In well-vascularized tissue, a rate of 1mm/day can produce good regenerate bones
  • In bone with poor blood supply: Rate can be halves
    • Poliomyelitis
    • Thromboangitis obliterans
  • Younger children in the femur, Achrondoplasia: rate can be doubled

Rule 5: Rhythm of distraction

  • Rate 1mm/day-> distraction into 4 distraction turns each 0.25mm/day
  • Higher rhythm: better bone formation
  • Lower rhythm ( 0.5 mm twice daily, 1 mm daily): slow down bone formation

Rule 6: Intact Vascularity

  • Essential for good bone formation
  • Limb has undergone radiation-> Less likely to form bone

Rule 7: Preserved function

  • New bone formation occurs best when the patient is able to walk and retain its function
  • An exercise regime of 4-6 hr/day gives the best result, regenerate formation in homogenous and bone hardens quickly

Phases of Limb Lengthening in Ilizarov 


During this period the construct is kept still with no lengthening.

5-15 days


  • 1 mm/day
  • For 6 days/week
  • 1 inch/month
  • Should be monitored radiologically

If regenerate bone formation is patchy, non-homogenous or defective==> better to slow down distraction

Sometimes it is better to stop distractions together for a few days


After lengthening ends, can last for 2-3 times as long as the lengthening phase

Adequate Stability+ Resumption of function + Good nutrition ensure hardening

Formation of at least 5 cortical walls (out of 8) as seen in AP, lateral and 2 oblique views is necessary for removal of Ilizarov apparatus and prevention of refracture or bending of bone.

See also: External Fixator Principles

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