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Procedure for RapidFit™
Thermoplastic Lock Adapter Procedure For Transtibial
and Transfemoral Thermoplastic Sockets
(RapidFit # 5013)
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
RapidFit # 5013 is not smooth, has undercuts and is
not removable
Materials Needed: Lock, RapidFit™
Thermoplastic Lock Adapter Adapter # 5013, and 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 Adapter. NOTE: Using the longer nails
provided in the RapidFit Adapter 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 in the screwdriver slot on the
round fabrication sleeve with (Fillauer) 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.
- Install the center plug with
through hole and O ring on the bottom of the
RapidFit Adapter and tighten. Attach the 3/8"
four-hole fabrication spacer block to the bottom
of the RapidFit Lock Adapter with the four 6 mm
socket head cap screws. Tighten the four screws to
the spacer block with a 6mm hex key.
- 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.
- Fasten the Lock Mechanism
with the RapidFit Lock Adapter to the plaster
model using the 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.
- Vacuum form the test socket
using the blister or drape methods. For drape
molding with an open non-welded seam, leave the
plastic on one side of the Vivak. Place the side
of the Vivak with the plastic facing up in the
horizontal oven during the heat process. The oven
temperature will vary 355 -360 F for about 20
minutes. The side with the plastic on it will be
turned toward the cast for vacuum forming and this
will act as a separator. Fastener screws will be
needed to secure the plastic seam if this
procedure is used.
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 3/8"
four-hole 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.
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 and tighten the eight
5 mm socket 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 to a torque setting of 12 Nm
or 9 foot pounds. Caution, care must be taken to
use the correct length socket head cap screws
provided with RapidFit Adapter so that the screws
tighten properly and securely. Do not substitute
these socket head cap screws.
- 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 with the RapidFit Adapter. Caution,
care must be taken to use the correct length flat
head screws provided with the Rapidfit Adapter so
that the screws tighten properly and securely. Do
not substitute these flat head screws. 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.
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