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Procedure for RapidFit™
Transfemoral Test Socket Adapters for Lock Mechanisms
(for # 1105, 1110, 1115, 1205, 1210, 1215).
Swanson Regional Orthotic & Prosthetic Research Center has developed
the
RapidFit Method to improve patient care for lower
limb amputees.
RapidFit
Overview
Before you begin: Read
directions completely
Materials Needed: Lock, RapidFit
Transfemoral Thermoplastic Lock Adapter, Mold Sealer
Tools needed: 5mm Hex Key, 6mm
Hex Key, #2 Phillips Screwdriver, Standard
Screwdriver, Cast Saw
Plaster Model Preparation
- Take the cast over the
suspension liner.
- Fill the cast with plaster
keeping the pipe 2" from the bottom of the
cast. The plaster model will have a center
protrusion replicating the distal end of the
suspension liner.
- Drill a ¼" hole
straight down through the center protrusion 1
1/4" deep.
- Flatten the distal end of the
model by removing plaster until the diameter of
the distal end of the model is equal to the outer
dimension of the attachment tooling.
Caution: DO NOT exceed the outer dimension of
the tooling, because the socket would be too
short. If too much plaster was removed, add back
plaster to correct.
- Check how the tooling is
centered on distal end of the model. Any voids
between the model and the tooling should be filled
with plaster to create a smooth transition.
- Seal the plaster model using
an appropriate mold sealer such as cellulose
crystals dissolved in acetone.
- Tie a knot in the distal end
of a non-stick nylon stockinette. Apply the
non-stick nylon stockinette to the plaster model
for a vacuum air wick. The knot should be centered
on the distal end of the plaster model.
- Paint the distal end of the
cast around the knot in the nylon with a mold
sealer such as cellulose crystals dissolved in
acetone. This will glue down the nylon for
trimming. Let dry and trim the nylon in a circular
shape slightly smaller than the lock mechanism.
- Fasten the attachment tooling
with the four long nails provided with the
RapidFit Kit. NOTE: Using the longer nails
provided by the RapidFit Kit will provide a more
secure attachment.
Lock Preparation
- Read the lock manufacturer's
directions for preparing the lock for attachment
to the plaster model. Remove the lock cartridge
from the lock mechanism. Install and tighten the
round fabrication sleeve with a standard
screwdriver. Fill the slot in of the round
fabrication sleeve with fitting gel or clay putty.
- Attach the lock to the
RapidFit Lock Adapter with the six screws. Note:
the 6 x 3/8" stainless steel sheet metal
screws are used with the Delrin lock bodies and
the socket head cap screws are used with metal
bodies. Use a #2 Phillips Screwdriver to tighten
the sheet medal screws.
- Attach the ½" four-hole
square spacer block to the RapidFit Lock Adapter
with the four 6 mm socket head cap screws. Do not
over tighten the screws into the spacer block.
- Install the eight 5 mm hex
socket set screws in the RapidFit Adapter. Install
the eight 5 mm hex socket set screws in the
RapidFit Adapter. The setscrews should protrude
3/16" for 3/16" plastic or ¼" for
¼" plastic to the mark the location for easy
removal. Tighten with a 5 mm hex key.
- Check the fit of the Lock
Mechanism, RapidFit Lock Adapter and posterior
foam contour to the plaster model. If there is
excessive material on the posterior foam contour,
it should be altered by sanding the foam where
needed. If there is gapping under the posterior
foam contour, it may be secured to the model with
double stick tape or by nailing through the foam.
A small amount of gapping will be pulled in by the
vacuum and heat from the thermoplastic. Fasten the
Lock Mechanism with the RapidFit Lock Adapter and
posterior foam contour to the plaster model using
the 1 ¾" socket head cap screw provided with
the lock mechanism. The Prosthetist should check
and adjust the RapidFit position for correct
rotation, then tighten with hex key.
- Place the plaster mold
horizontally in the vacuum figure so that the
anterior side of plaster model faces the floor.
Vacuum form the test socket with an anterior seam.
Trimming
- Let the test socket cool
down. Sand off the plastic on top of the lock
attachment bolt and remove the bolt with a hex
key.
- Trim out the ½"
four-hole square spacer block. Remove the four 6
mm socket head cap screws with a 6mm hex key.
Remove the four-hole spacer block.
- Trim out and remove the test
socket from the plaster model. Sand and buff the
trim lines.
- Sand off the plastic on top
of the eight 5 mm hex socket set screws and remove
screws with a 5 mm hex key.
- Sand off the plastic covering
the round fabrication sleeve and remove it with a
standard screwdriver.
- Install and tighten the eight
5 mm button head cap head screws and stainless
steel washers to secure the attachment of the
RapidFit Lock Adapter to the test socket. Tighten
with a 5 mm hex key.
Assembly
- Remove any fitting
gel or stick wax residue from the lock body and
threaded attachment holes. Follow the lock
manufacturer's directions to reassemble the lock.
- Install the other
endoskeletal components according to
manufacturer's directions. NOTE: A set of four 6
mm x 16 mm stainless steel flat head socket screws
are provided for your convenience. Apply thread
lock such as Loctite 242 to the four 6mm x 16 mm
stainless steel flat head socket screws and
tighten to a torque setting of 12 Nm or 9 foot
pounds.
Filling the Test Socket
- Fill the locking
pin hole with fitting gel or clay in order to
prevent plaster from leaking into the lock
mechanism. Tape over the posterior foam contour on
the inside of the socket with masking tape in
order to prevent the plaster from leaking into and
around the lock mechanism.
- Mark the location of the
locking pin on the model for the fabrication of
the definitive socket.
Transfemoral RapidFit Socket
Lamination
- You will need a
RapidFit Kit for laminated sockets. Follow the
RapidFit lamination directions.
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