Page 208 - WSAVA2018
P. 208

 25-28 September, 2018 | Singapore
A. Piras1
1Specialist in Veterinary Surgery, Ravenna, Italy
Top Tips in Using Cerclage wire in Fractures Repair
Alessandro Piras
DVM - Specialist in Veterinary Surgery
Principles and Clinical Application of Cerclage Wiring
Orthopedic wire is used as a supplementation for fracture fixation for the reduction of fragments and the protection of fissures. Never use wire as a sole means of fracture repair. It is most commonly used as an adjunct to intramedullary (IM) pin fixation. The degree to which this device helps to neutralize the remaining forces acting on the fracture site also is directly dependent upon the fracture configuration; for example, full cerclage wires effectively neutralize rotational, compressive and shear forces in a long oblique fracture - but are ineffective in a short oblique or transverse fracture.
Orthopedic wire is provided as a malleable form of 316L stainless steel. It comes in a range of diameter, from 0.5 to 1.5 mm (2416 gauge). The two types of orthopedic wire available are gauge wire and loop wire. Gauge wire comes in spools or long strips (coil type). Loop wires have a preformed eye at one end for a single knot and are available in 0.85, 1.0, 1.25, and 1.5 mm diameters and in 150 and 300mm length.
Tightening methods
The three most common methods for tightening and securing cerclage are twist, single loop, and double loop knots.
Twist knot (a): To form a twist knot, old needle forceps or pliers can be used. Instruments that lock the two strands may help ensure that the twist forms with an even wrap. The first two to three twists should be formed by hand. The loose twist is then grasped with the instrument and further twists formed while pulling very firmly away from the bone. This will ensure that the twist is tightened at its base, and that the wires wrap around each other NOT one around the other. Once the wire is tight, (meaning that doesn’t longer moves if pushed) or the surgeon feels that further twist will cause the wire to break, the twist
is cut leaving 3 wraps of wire. It is very important not to wiggle the cerclage wire while cutting it otherwise there is the risk of undoing the twist and loose the tension. Another important recommendation is to not push the
twisted wire down to adhere to the bone surface as this maneuver will generally reduce the initial tension.
Single loop knot (b): Single loop knot is formed using
a length of wire with an eye at one end. The free end is passed around the bone and through the eye, and tip
of the tightener. It is then passed into the wire tightener rotating crank. The wire is tightened around the crank, and by rotating it the wire is tightened. Once the desired tension is achieved, the wire tightener is bent over to lock the free end within the eye. The wire tightener is loosened and the free end pushed down so that it is bent back completely on itself. The wire is then cut, and flattened further if needed.
Double loop knot (c): Double loop knot is formed using a length of wire that is folded over on itself to present
a double strand of wire. The fold is compressed but left open enough to be able to pass two strands of wire through the bent end. The folded end is passed around the bone, and the two free ends passed through the loop. The wire is pulled tight. The free ends then are passed into the wire tightener using 2 cranks. Each wire end is loaded into one of the cranks in the same manner as for single loop cerclage. The two cranks are tightened simultaneously until the tension “feels” appropriate, and the wire tightener is bent over, again while maintaining tension in the cranks. Once the bends are sufficient, the cranks are loosened, and the bending completed so that the wire ends lie flat to the bone. The wires are cut, and the arms flattened further if needed.
Clinical considerations
Full cerclage wiring: Full cerclage wiring is when the wire is placed around the bone. This technique is used for long spiral and oblique fractures and to protect fissures. The bone must be completely reconstructable for this technique to work. General “rules” for full cerclage wire application follow:
· The length of the fracture line obliquity should be at least twice the diameter of the bone.
· All wires should be spaced approximately 1.0 cm apart, and all wires should be placed at least 0.5 cm form the end of a fracture.
· All wires need to lie directly on bone (no interposition of soft tissues)
· All wires must be placed perpendicular to long axis of the bone.
· All wires should be placed and tightened before the primary fixation applied.
Hemi-cerclage wiring (Inter-fragmentary wiring): This is used to counteract forces of rotation and shear in transverse and short oblique fracture. Drill holes in each bone segment and pass the wire through the holes. This technique adds little to the mechanical stability of a fracture. The holes in the bone weaken the fragment ends. Inter-fragmentary wiring are useful for repair of some mandibular.

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