TENSION STRESS EFFECT
“slow, steady traction of tissues caused
them to become metabolically activated,
Resulting in an increase in the
proliferative and biosynthetic function”
Distraction forces can create tissue stress capable
of stimulating local metabolic activity with cell
transformation. This eventually leads to the
development of bony regenerate
Quality and quantity of newly formed bone
depends upon several factors:
• The regidity of bone fragment fixation
• The degree of damage of the bone marrow, the
periosteal, soft tissues and the nutrient blood
vessels at the level of the osteotomy
• The speed of a distraction (rate)
• The rhythm (frequency) of a distraction
• The distribution of forces on the bone
Treatment with the Ilizarov technique consists of five
1. Fixator application and a following latency period of
4 to 7 days.
2. Period of distraction/compression of 1 to 4 or 5
months (depending on the case).
3. Period of immobility and fixation of the bone
position. This usually takes twice as long as
4. Discontinuation of distraction-compression and
frame dynamization 15 to 20 days prior to fixator
5. Period of immobilization with a cast or brace.
The range of the wire tensioning strength is 50 to
130 kg. General recommendations for the suggested
tensioning strengths are as follows:
1. Wire on half-ring: 50 to 70 kg
2. Offset (drop) wire, depending on size of the
supporting posts: 50 to 80 kg
3. Single wire on a ring: up to 100 kg
4. Two to three wires on a ring in a young patient:
110 kg for each wire
5. Two to three wires on a ring in an adult patient: 120
to 130 kg for each wire
6. Wire with an olive stopper: 100 to 110 kg
7. Wires with olive stoppers used for interfragmentary
compression, depending on bone condition; 50 kg.
In the Ilizarov procedure the bone cut serves three
1. To create mechanical conditions (a gap) necessary for
the development of distraction
2. To store the new bone-forming cells that were
developed during lengthening and deposited along
the lines parallel to the mechanical stress
3. To develop the area with increased blood circulation
necessary for increased metabolic transformation of
Typical mistakes that occur with the corticotomy
1. Skin incision too large.
2. Periosteal separation at the site of initial bone cut
and around the bone.
3. Use of an oversized osteotome.
4. Poor choice of level of corticotomy.
5. Destructive hammering of the compact bone.
6. Direct cut through bone marrow canal.
7. Induction of the bone cut into the nearby wire tract.
8. Injury of the nearby magistral vessels and nerves.
9. Performance of the twisting osteotome maneuver
before cuts are completed through medial and lateral
10. Loss of fragment alignment.
Any of these mistakes can complicate bone
The advantages of using the Ilizarov fixator in fracture
1. Possibility of simultaneous anatomic reduction of the
2. Stable fixation provided by the wires, introduced at
multiple levels and in multiple planes and orientations.
3. Early functional treatment, including joint range of
motion and weight bearing, that stimulates fracture
healing and shortens treatment time.
4. Possibility of correction of the secondary displacement
by frame adjustment.
5. Easy approach to wounds in cases of compound
The following is a list of the four most important
factors in the Ilizarov fixator removal technique.
1. The tension of all wires must be released before they
are cut. Because the wires are under tension of more
than 100 kg, cutting them produces extreme pain,
which the patient can feel even under sedation and
superficial anesthesia. Moreover, when the wire is cut
while still under tension microinjury and even stress
fracture in the regenerate may be provoked.
2. All olive wires (or the other wires with stoppers) must
be removed by extraction toward the stopper. Sometimes
this requires the application of considerable strength.
There also may be a blood vessel near the
stopper, which will cause some bleeding to occur.
This requires that the surgeon apply pressure with the
finger for several minutes.
3. Extraction of the wires with large pliers must be don
strictly in the direction of the wire position and
orientation in the bone.
4. Removal of the half-pins requires careful turning of
the T-shaped hand drill because of their tendency to
break in the bone. Because these pins are under
tension for a long time, metal fatigue and microfailure
can develop, causing the pins to break when turned.