Immobilization (fixation) of fracture:
Immobilization consists of fixing the bone fragments so that they are motionless during the healing process. The purpose of immobilization includes:1- Minimize pain.
2- To fix the fragments in the desired position.
3- Prevent displacement, angulation and rotation of bone fragments.
There are 3 general methods of fixation:
1- External fixation ( coaptation splints and casts):-
These devices consist of a mold of material that surrounds the affected part and holding fractured bones in reduction until healing occurs. Many materials are available for this purpose, including plaster of paris, metal strips impregnated gauze, aluminum backed with sponge rubber and fiberglass.
The following points should be considered in application of external immobilization:
1- Coaptation splints are limited to fractures distal to the elbow and distal to tibia and fractures of tail.
2- If closed reduction is used the hair is usually not clipped. A light padding (stockinet or cotton) should be applied to protect the soft tissues over bone prominences.
3- The cast or splint should fit and be well-molded to the limb without interfering with blood circulation. The period of greatest danger is between 12 and 36 hours after applying the cast. Pain, elevation of temperature , and swelling of digits with cyanosis and numbness are warning sings that require assessment of circulation.
4- The joints proximal and distal to the fracture should be immobilized by the cast.
5- After the cast has been applied reduction should be checked by radiographs taken in 2 different views.
6- If the cast is not well tolerated by the patient it is either not properly applied, the animal’s activity is not sufficiently restricted or the cast beyond its capacity.
Steps of applying plaster of paris cast (gypsona):
1- The fracture should be reduced and maintained in position.2- The leg is then covered with a thin lining of stockinet or cellulose bandage.
The plaster can be applied as a round-and-round bandage with longitudinal strips or slabs to reinforce a particular area.
3- When the cast is being applied care should be taken to avoid angulation and rotation of foot.
4- After the plaster has dried the entire cast is covered with tape because most dogs will chew the cast.
Application of plaster of paris