It is the basic step in the manufacturing of the
prosthesis after the assessment of the amputee and prescription of the right
type of prosthesis for him. Casting provides a modifiable model to be worked
upon.
There are many methods of casting conventionally casting
is done by means of sketching the stump on the paper. As it is not the precise
way of casting so other methods are used e.g. sand casting & plaster wrapping
cast. Plaster wrapping cast is the most commonly used procedure now days.
Plaster wrapping cast is the most convenient and
versatile 7 is used in all types of plaster cast work. It’s very simple to make
cast of variable thickness and tightness using the plaster.The important features of the plaster wrap cast are:
•
Stump is placed in flexed condition and is
marked to highlight certain anatomical areas.
•
Bandage is applied with a moderate and even
tension to achieve a relatively undistorted cast.
•
Finger pressure is applied on the weight bearing
areas so that resulting indentation helps in modification guidance.
Things needed for
casting:
Following things are needed for a plaster wrap cast;
Tools:
Couch to sit
the patient
Stool for Prosthetist
to sit
Plastic sheet
to be placed under the patient
Towel to cover
the sound side of patient
Steel ruler to
mark the reference lines
Basin of clean
water to wet the bandages
Cast cutting
scissor to start cutting the cast
Surgical knife
to cut the cast
Venire calipers to
take the AP and ML measurements
Measuring tape
to take circumferences
Cutting aid to
help in cutting
Materials:
Vaseline used
as separating agent
Stockinet to
shift the markings on cast
An indelible
pencil to mark the important land marks
Pop bandages
for casting
Clean swaps
for cleaning the patient after casting
Measurement chart to
fill in the measurements
Procedure:
Casting is divided in to:
Place preparation
In place preparation the student have to clean
the casting area and place the plastic sheet on the couch a place the material
to be used in the casting in proper place change the water in the water basin
and place measurement tools apart from cutting tools.
Patient preparation
First patient is assessed and counseled about
the procedure. And then is sufficiently exposed to take the casting and seated
on the couch.
Casting
After the preparation I thin layer of the
Vaseline is applied over the stump. Then pull a thin, moist sock over the
stump. The stump is held at about 20*-30* flexion
during entire process of casting for certain bony prominences, aids in
definition of the patella tendon and will locate the insertion of hamstring
tendons. Place the cutting aid under the sock. Mark the
wet sock with indelible pencil, indicating prominences and other sensitive
areas. The prosthetic information form must be
completed before the cast is taken
Marking areas
•
Patella
•
Patellar tendon
•
Tubercle of tibia
•
Head of fibula
•
Tibial crest
•
Distal end of fibula
•
Anteriodistal end of tibia
•
Proximal end of medial condoyle
Sensitive areas
•
The sensitive areas are to be provided relief,
these are:
•
Tubercle of tibia
•
Head of
fibula
•
Tibial crest
•
Distal end of fibula
•
Distal end of tibia
•
Any other area showing any deformity( bone spur,
Neuroma, adherent scar tissue etc
Relief on these areas is provided by pop straps
Unwrap the pop bandage 15 cm (as many as needed)
and place them on the floor beside the water basin. Apply the cut pieces of the pop over the
pressure sensitive areas to provide relief on those areas in casting, cover the
pieces of pop with thin layer of Vaseline. Submerge the pop bandages individually in the
water basin for few sec. until the bubbles stop coming out of the bandage now
squeeze it gently before applying to the stump. Now apply the pop on the stump with no tension
in wrapping and wrap it from mid patella down to the stump end, overlapping one
half the width of plaster bandage with each layer. Make sure that 4 to 6 layers of the bandage have
been applied throughout the stump. Smooth the cast by massaging it up and down. Ask the patient to relax his muscles and keep on
massaging the cast to make the bony areas of the stump prominent keep on
working until the cast hardens. As the plaster hardens place the end of the
thumbs to deepen the impressions for patellar tendon on both sides the thumbs
should be placed at 30*-45* to tibia on both sides and counter pressure is
applied by the fingers from popletial area. Now start wrapping the cast from the base of
patella to cover the lover ¼th of thigh. Then a force just above the medial condoyle
of the femur is applied for suspension purpose. Now the cast is cut at the cutting aid and
cutting aid is remover and then the cast is remover off the patient and is
trimmed to a desirable position now the reliefs are removed from the cast, this
is the negative cast. The check socket is than fitted to the patient.
Ask the patient to bare weight on the socket supporting the socket by your
hands. This will help in getting the idea for
modifications to be made in the positive cast after filling. Now transfer the reg. no. and names of the patient
and Prosthetist to the cast.
Patient cleaning
This is one of the most important steps of
casting. After the removal just after closing the cast properly closed and refreshing
the markings carefully, the stump of the patient should be cleaned using proper
antiseptic solution. Prepare the cast for filling.
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