PRAC: IM pin and cerclage

IM pin forces

very resistant to bending but do not counter rotation - cannot be used alone

IM pins are often combined with

cerclage or lag screws to provide rotational stability

the most common tool for i/m pinning

A Jacobs Chuck

IM pinning - which bones is it and what it isnt used to?

Commonly used on femur, tibia, humerus

Should not be used in the radius, cause DJD

What bone should IM pinning be avoided in and why?

Radius, causes DJD

Placement and IM pinning - normograde vs retrograde

Normograde - through the end of the bone

Retrograde - through the fracture point

Cerclage wiring

Only applicable for...

reconstructible Fxs that are long oblique or reconstructible wedge (mildly comminuted)

Cerclage wiring

Need at least...

USE AT LEAST TWO full cerclage, one can act as a pivot point and is subject to loosening

Cerclage wiring

Size

Use the largest size wire practicable 18 G large dogs, 20 G med dogs, 22 G small fragments and some cat fxs

The length of obliquity rule

An oblique fracture should only be considered for cerclage wiring when the length of the fracture face is greater than twice the width of the bone at the fx site

Problems with cerclage (3)

When the loops are loose they damage the recovering blood supply

Loose loops migrate into the fracture site and the vascular impedance leads to non-union

In immature patients they prevent circumferential bone growth