RapidFit Overview

Before you begin: Read directions completely

Materials Needed: Lock, RapidFit Transfemoral Lamination Lock Adapter, Mold Sealer, Dacron Felt, Nyglass and Perlon Stockinettes, PVA Bag and Acrylic Resin.

Tools Needed: 5mm Hex Key, #2 Phillips Screwdriver, Standard Screwdriver, Cast Saw, Channel Lock Pliers

Plaster Model Preparation 

1. Take the cast over the suspension liner.
2. 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.
3. Drill a ¼" hole straight down through the center protrusion 1 1/4" deep.
4. 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.
5. 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.
6. Seal the plaster model using an appropriate mold sealer such as cellulose crystals dissolved in acetone.
7. 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.
8. 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.
9. Apply the PVA bag and cap the distal end.
10. Cut a round piece of stretch tape the same size as the attachment tooling and apply to the PVA over the drilled hole. The tape will help prevent the PVA from tearing. Puncture a hole in the tape over the drilled center hole. 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 

11. Read the lock manufacturer's directions for preparing the lock for attachment to the plaster model. Remove the lock cartridge from the lock mechanism. Fill the interior of the lock body with fiiting gel or stick wax to prevent plastic from leaking into the lock. Install and tighten the round fabrication sleeve with a standard screwdriver.
12. Attach the lock to the RapidFit Lock Adapter with the six screws. Note: the 6 x 3/8" stainless steel sheet metal screws 6 x 3/8" 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.
13. Lubricate the four size M6 x 45mm socket head cap screws for easy removal. Attach the four-hole 1 ¼" square spacer block to the RapidFit™ Lock Adapter with the four socket head cap screws. The side with the two rounded edges on the spacer block goes to the posterior side of the RapidFit Adapter. Lubricate the M6 X 25mm socket head cap screw and install in the middle hole in the square spacer block.. Tighten all screws with 5mm hex key. Fill the screw heads, set screw for lock cartridge and slot in the round fabrication sleeve with fitting gel or clay putty.

Lay-Up Example

14. Apply one layer of ½ ounce Dacron Felt. Trim out a circular hole in the Dacron the same size as the nailed round holding spacer. Be careful not to cut the PVA bag.
15. Cut a round section of ½ ounce Dacron Felt about 9" in diameter. Trim out a circular hole in the Dacron slightly smaller in size as the nailed round attachment tooling. Apply this round Dacron Felt on top of the first layer of felt. Place the hole over the attachment tooling. This is needed to hide the carbon tape on the inside of the socket.
16. Apply the 1" carbon tape reinforcement through the anchor holes in the RapidFit Adapter. Apply additional 1" carbon tape as needed according to the patient's activity level.
17. Fasten the Lock Mechanism with the RapidFit Lock Adapter 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. Fill the screw head with fitting gel or clay putty.
18. Cut two layers of 2" nylon stockinette 1 ½" long. Apply the two layers around the lock mechanism between the spacer block.
19. Apply two layers of Nyglass stockinette, twisted in middle and reflected back. The twist should be over the square spacer block. Note: Spectralon™ stockinette may be substituted for Nyglass.
20. Apply two more layers of Nyglass stockinette, twisted in middle and reflected back. The twist should be over the square spacer block. Note: Spectralon stockinette may be substituted for Nyglass.
21. Apply two more layers of Nyglass stockinette, twisted in middle and reflected back. The twist should be over the square spacer block. Note: Spectralon stockinette may be substituted for Nyglass.
22. Apply two layers of finish stockinette such as Perlon, twisted in middle and reflected. The twist should be over the square spacer block.
23. Apply the outer PVA bag and pour cone. Laminate with acrylic resin such as Epox-Acryl. Wrap around the lock mechanism with a 2" ace wrap to reduce pooling of the resin. Tie off the excess resin with a string.

Shell Lamination for a cosmetic cover 

24. Fill any undercuts with clay putty or fitting gel. Apply one cotton or nylon stockinette for a separator. Apply the inner PVA bag and tie off the top. Apply two nylon stockinette twisted and reflected back. Apply the PVA Bag and pour cone. Laminate with 80-20 polyester resin.

Trimming 

25. Let the lamination cool down. Sand away the material covering the end of the lamination over the lock screw. Remove the lock socket head cap screw with a hex key.
26. Sand away the material covering the end of the lamination over the five socket head cap screws. Remove the four size M6 x 45 mm socket head cap screws with a 5mm hex key.
27. Trim out the four-hole square spacer block. Remove the 1 ¼" four-hole square spacer block. Use the middle M6 x 25mm socket head cap screw to pull out the square spacer block or use channel lock pliers.
28. Trim out and remove the socket from the plaster model. Sand and buff trim lines.
29. Sand off the plastic covering the round fabrication sleeve and remove it with a standard screwdriver.
30. Clean off any excess plastic on the RapidFit Adapter.

Assembly

31. 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.
32. nstall 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.

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