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SURGERY
tem and their parts are interchangeable within their
own systems.
The clamps should always be placed with the clamp
adjacent to the skin to limit the distance from the
bone to the connecting bar. The more one increas-
es the distance between skin surface and clamp, the
longer the working length of the pin the higher the
rate of pin loosening and implant failure.
Acrylic systems are available but the bond between
pin and connecting bar is not as strong or reliable as
the two above-mentioned systems. Acrylic does give
the advantage of being very flexible where the pins
are placed and can be useful for hard to repair bones
like the mandible. The most commonly used com-
mercially available system is the Acrylx® from Imex.
One can make a acrylic side bar from hoof acrylic and
an old anaesthetic breathing tube cut to size.
Connecting Bars
Connecting bars are the main buttress or support of
the bone while the fracture heals (figure 4). In the ex-
ample of a ESF placed on the leg, they transfer the
weight of the patient through the leg, through the
pins, down the connecting bars and back into the
foot. Bars need to be lightweight but strong enough
to support the forces transferred through them for
the size of the animal. Bars are made from a variety
of materials, the most common being carbon fibre,
stainless steel and titanium alloys.
Figure 3. Circular ring fixator for a growth deformity
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vet360
Issue 05 | OCTOBER 2017 | 14
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Carbon fibre has the advantage of being radiolu-
cent and allows visualisation of the fracture during
healing. It is very light and in large constructs can
be useful to increase mobility of the patient. How-
ever they are prone to wear and tear and will need
to be replaced more often.
Stainless steel is heavier that carbon fibre and is
radio-opaque which can impair visualisation of
the fracture during healing. The advantage is they
are more resistant to wear and are cheaper that
carbon fibre.
Titanium alloys are light, strong but more expen-
sive than both carbon fibre and stainless steel.
As the number of bars increase in the construct the
rigidity of the construct increases. Placing cross bars
further increases the stability of the construct.
Can Fixators be Applied Anywhere?
Yes. The reality is that they can be used in any bone
anywhere in the body. There are however certain
bones which they work better for. The general rule
is that bones with less soft tissue coverage tolerate
ESF better. They have less pin loosening and have less
pin-tract complications, most commonly pin tract dis-
charge. This is due less soft tissue between bone and
skin rubbing on the pin and hence less reaction.
Generally the tibia, radius and ulna, metatarsus and
metacarpus tolerate ESF very well (Figure 5). Surpris-
ingly the humerus tolerates the method well and is
Figure 4. Type III ESF with crossbars