SURGERY
Article sponsored by Petcam ®
Loading mode
Load sharing
Transverse
Oblique
Butterfly
Load sharing
Load bearing
Torsion
Bending
Compression
Tension
Spiral
Fracture type
Figure 2: Load distribution between bone column and implant.
Figure 1. Forces acting on a fracture.
These forces should be adequately neutralised by the
implants in order for fracture healing to occur. Frac-
tures that are subjected to compressive (shear) and
distractive (tension) generally require internal fixation.
Reconstruction of the bone column, when achieva-
ble, is preferred as this allows load sharing between
the bone and the surgical implant protecting the im-
plant from cyclic fatigue and failure before fracture
healing. (Figure 2) During scenarios where the bone
column cannot be reconstructed all the forces are
transposed to the surgical implant predisposing them
to failure. In the latter scenario the selected implants
need to be larger and stronger to resist the forces
acting on it until fracture healing has occurred.
For the major long bones, it is respectively at the fol-
lowing locations:
• Humerus - craniolateral
• Radius
- cranial
• Ulna
- caudal
• Femur
- lateral
• Tibia
- lateral
In some instances, the ease of the surgical approach
dictates the location of the plate for example in tibia
fractures which are usually plated on the medial as-
pect. Implants placed on the tension surface are only
stronger if the cortex on the compression side can
be anatomically reconstructed. If this is not the case
the forces acting on the implant will be changed to
bending forces.
Surgical Approach and Fixation
The selection of the surgical approach depends on
the location of the fracture and the planned place-
ment location of the implants. Implants are more
resistant to tension than to bending and thus the im-
plants are preferentially placed on the tension side of
the bone.
vet360
vet360
Issue 06 | DECEMBER 2017 | 18
It is advisable to follow a structured course in the art
of oesteosynthesis to understand the applications
of the different techniques. Technical errors during
implant placement cannot be over emphasised and
most of the implant failures can be traced back to im-
proper implant placement. These errors can include