CAPTURING THE SHAPE
If you use the OMEGA
System, refer to the OMEGA User's Guide for directions .
®
If making a
hand cast,
Don the Alpha Liner .
follow these
Cover with plastic
steps:
protection and
a cast sock, then
apply gypsum tape
over the cast sock .
CAST MODIFICATIONS (NO BUILD-UP ON THE POSITIVE - NEVER)
Reduce the positive model as follows to obtain Total Surface Weight Bearing:
Uniform, Tapered, Contoured
3 mm
3-5%
To reduce a plaster positive:
Goal:
(1)
(3)
(1)
symmetric layer
removed
(2) original positive
(3) modified positive for
an Alpha socket
Note:
The suggested reduction
amounts are starting
points . You may need
to reduce slightly more
or less based on casting
technique and limb
conditions .
Using long continuous strokes, repeated 3 or 4 times
at each spot, remove an even layer everywhere,
following all contours without changing them . Do
NOT reduce the length . Having reduced the whole
surface, re-measure at each awl hole . Repeat until
you have achieved the goal circumferences .
Press only on the two
sides of the patella tendon .
6 mm
9 mm
5-7%
7-9%
Method:
(2)
round file
minimal patella bar
Carve a patella bar that
is straight and no deeper
than the depth of your
finger marks . (Patella bar
is optional .)
half round file
Do not influence the
shape .
Progressive
AK
5-7%
3-6%
awl or similar tool
Make a series of reference
marks along the model,
approximately 3 cm apart .
Pierce the model at each
of the marks .
Wrong modification
(plaster was not removed
symmetrically) .
3
Do not push in on the
posterior wall at all .
Measure and record the
circumference at each
of the marks . Reduce
each circumference
by the amount listed
above to obtain the goal
circumferences .
Do not add plaster –
not even at the fibula head
or at the distal tibia .