Cerclage wires (Lewis) Flashcards
Cerclage wires
Definition
- Heavy gauge stainless steel wire placed circumferentially around bone
- provides fragment apposition and adjunctive fixation
Cerclage wires:
Function
- Provide fragment apposition
- Inadequate stability to resist forces of weight-bearing alone
Ability of various implants to neutralize fracture forces
- Forces
- Rotational
- Bending
- Shearing
- Fragment apposition
- Implant
- Single IM pin
- Multiple IM pin
- Screws and Plates
- External Fixator
- Cerclage wires
First rule of cerclage wire application
- Need to have 360 degree anatomic reconstruction of cylinder of bone at the level wires are places
Fractures heal from:
End to end
-not side to side
Cerclage wires
Application
- Resistance to axial, rotational, bending and shear forces dependent on
- frictional forces generated when interdigitating intricacies of fracture surfaces are statically compressed
- Complete 360 degree anatomic reconstruction is mandatory
-
Wire must be of sufficient diameter
- 18, 20, 22 gauge wire
- Fracture must be oblique
- twice or 2.5 times in length as diameter of bone at level of fracture
- Use multiple wires to distribute the forces along the entire length of the fracture
- 1 cm apart
- placed 5 mm from end of fracture segments
- Place wire perpendicular to long axis of bone
- Must be tight
Cerclage wire
DON’Ts
- Don’t use on short, oblique fracture
- Don’t ever use a single cerclage wire
- One wire is like a teeter totter
- Do not allow soft tissue to be interposed between the wire and the bones
- but don’t strip soft tissue
Dead piece of bone not conjoined
Sequestrum
Preventing cerclage wire slippage
- Hemicerclage wire
- K wire perpindicular to fracture line
- Then cerclage wire around it
- proximal end proximal to k wire
- distal end distal to k wire
- Then cerclage wire around it
Loose implant will cause
infection
Layer of new bone growth outside existing bone seen in pyogenic osteomyelitis
Involucrum
Cerclage wires
Twist knot
- Both phases of application occur simultaneously
- Limits wire tension because wire is bent before it is tight
- Wire is pulled & deformed through multiple planes during application
- Usually use heavy needle holders
- Pull against wire, use elevator to make sure wire perpindicular to bone
*both sides need to be twisted around one another (not like a fireman on a pole)
Cerclage wires
Loop knot
- Wire is tightened and subsequently secured by bending
- Wire pulled through a single plane during application
*Can get much greater tension than with a twist knot
Cerclage wires
Biomechanics
- Loop knots produced greater tension than twist knots
- before and after bending
- Twist knot cerclage wires lost significant tension
- if bend over
- Twisted knots provide greater resistance to distractive forces
- Knot resistance to distractive forces increased with increasing wire diameter
Twist Cerclage wires
Advantages
- More resistant to distractive forces
- Simpler to apply
- Wires can be re-tightened
- More economical than loop wires
Twist cerclage wires
Disadvantages
- Final tension inferior to loop wires
- Can shift to situate obliquely to long axis of bone
- More cumersome to apply
- Twist protrudes into surrounding soft tissue
Loop cerclage wires
Advantages
- Greater final tension
- Situation perpendicular to the long axis of the bone
- Does not protrude into surrounding soft tissues
Loop cerclage wires
Disadvantages
- Less resistance to distractive forces
- Cannot re-tighten wires
- More cumbersome to apply
- Increased cost compared to twist wires
Cerclage wires
10 commandments
- wire must be of sufficient diameter
- DON’T USE STAINLESS STEEL SUTURE
- need 360 degree anatomic recostruction
- fracture must be oblique
- never use a single wire
- wires should be 1cm apart
- wires should be 5 mm from end of fracture segments
- no interpositioned soft tissue
- wires must be placed perpindicular to long axis of bone
- prevent slippage in regions where bone changes diameter
- wire must be tight
Pin and Tension Band Fixation
- Converts distractive forces to compressive forces
- Used to stabilize osteotomies & fractures at traction aphyses
A Tension band converts:
TQ
Distractive forces to compressive forces
