KAFO

in Strong Light Technique

When producing a Strong Light orthosis, materials are not reinforced or laminated. The orthosis’ bands are directly attached to the system side bars. The following construction serves as an example for this online tutorial:

  • bilateral ankle
  • bilateral knee
 Carbon Fibre Bands

Step 1/12

To produce an orthosis with maximum torsional stiffness, the carbon fibre bands should be cut in 45° fibre orientation.

Step 2/12

Choose the respective carbon fibre band material from our CTC BIDIREKTIONAL range. Available are carbon fibre sheets and pre-cut carbon fibre bands. The pre-cut carbon fibre bands already have a preproduced fibre orientation of 45°. Waste can thereby be reduced considerably.

Step 3/12

The strength categories of the pre-cut carbon fibre bands can be compared to the following thicknesses of metallic plates:
1.75mm alu -> H
2.00mm alu -> XH
2.25mm alu -> XXH
1.5mm V2A -> XXXH

Step 4/12

The pre-cut carbon fibre bands are available in different lengths, widths and thicknesses.

Step 5/12

Create a stencil on a model to saw out the carbon fibre bands.

Step 6/12

Transfer the stencil to the pre-cut carbon fibre bands.

Step 7/12

Saw the carbon fibre bands with a band saw or a jig saw.

Step 8/12

Ensure that the correct processing temperature is used with the aid of a temperature marker for 175°C. Mark each pre-cut carbon fibre band.

Step 9/12

Make preparations for the thermoforming of the pre-cut carbon fibre bands by fixing a rubber band (e. g. a bicycle tube) on the model. Apply a small amount of contact adhesive to the area of the carbon fibre bands and the pre-cut carbon fibre bands. By doing so, you can secure the thermoplastic carbon fibre bands in the desired position when thermoforming.

Step 10/12

Wrap the rubber band around with much pretension. After a few minutes, it can be removed again.

Step 11/12

Thermoform all pre-cut carbon fibre bands.

Step 12/12

Due to the fibre orientation of 45° the edges are slightly raised when thermoforming. This is a positive side effect, since the stability is thereby increased and the bands’ edges point away from the body.

 Assembling on the Parallel Alignment Devices

Step 1/2

Mount the system joints with the aid of the assembly/lamination dummies on the tools for the parallel alignment.

Step 2/2

Mount the system joints with the aid of the assembly/lamination dummies on the tools for the parallel alignment.

 Bending Articulated System Side Bars

Step 1/2

In order to avoid breakages of articulated system side bars, please note that the material must not be bent in radii that are too narrow. The bending radius depends on the thickness of the material. A general rule is that the bending radius should be 10 times larger than the thickness of the material. For example: If a system side bar is 5mm thick, the bending radius should be 50mm or larger. Use a bending iron with rounded edges in order to avoid stress concentrations!

Step 2/2

The articulated system side bars must not be worked with the pointed side of a hammer or driven. Risk of breakage!

 Checking the Joint's Parallelism

Step 1/1

The parallel alignment of the system joints can be checked with the parallel alignment gauge.

 Producing the Foot Piece’s Inner Shell

Step 1/4

Draw the area of the foot piece and create a stencil. Apply contact adhesive to the area of the foot piece. By doing so, you can secure the carbon fibre material in the desired position when thermoforming.

Step 2/4

Saw the foot piece with a band saw or a jig saw. Use the temperature marker to ensure the proper working temperature of 160 °C.

Step 3/4

Thermoform the thermoplastic material with a rubber band (e. g. a bicycle tube).

Step 4/4

Make sure to avoid wrinkling in the heel area when thermoforming.

 Processing the System Stirrups

Step 1/3

To produce the orthosis’ foot piece with the sandwich construction method, we recommend using the forked system stirrup (thermoforming). It automatically wedges between the individual layers of the foot shell.

Step 2/3

The system stirrup is marked with lines in the joint head area which facilitate a precise filing of the system stirrup in dorsal and plantar direction.

Step 3/3

Bend the system stirrups as close to the inner shell as possible. Make sure that the head area of the system stirrup does not get deformed when bending close to the system stirrup. This could lead to a functional impairment. Smoothen the system stirrup’s edges.

 Preparing the Fitting

Step 1/4

Mark the positions of the carbon fibre bands on the articulated system side bars.

Step 2/4

The carbon fibre bands are screwed together with the system side bars for the fitting to ensure that changes can be made afterwards. 

Step 3/4

After a successful fitting, the screw connections are replaced by an adhesive connection and additional riveting.

Step 4/4

Build the entire orthosis with trial screws. After making the changes, where appropriate, the system components can be adhered and riveted together.

 Adhering the System Side Bars/System Joints

Step 1/2

Degrease the system components with a non-greasy solvent and apply the adhesive AGOMET® F330.
Note: Mind the safety data sheet when using the adhesive AGOMET® F330.

Step 2/2

The adhesive AGOMET® F330 also aids in securing the pan head screws.

 Adhering the Carbon Fibre Bands/System Side Bars

Step 1/5

Use the adhesive AGOMET® F330.
Note: Mind the safety data sheet when using the adhesive AGOMET® F330.

Step 2/5

Roughen the surfaces slightly and clean them with a non-greasy solvent. Apply the adhesive AGOMET® F330 to the surfaces.

Step 3/5

Put the system components together with trial screws. Remove the adhesive that leaks due to the contact pressure before it hardens. This can not be done after the adhesive has hardened.

Step 4/5

Remove overlapping band’s ends and smooth the cutting edges.

Step 5/5

Remove the trial screws after 1-2 hours. Rivet the system components together.
Important: If you wait too long before riveting, the adhesive has hardened and is no longer flexible. The adhesive might then come off when riveting.

 Producing the Foot Piece’s Outer Shell

Step 1/6

Produce the second foot piece shell above the system stirrups.

Step 2/6

Use the adhesive AGOMET® F330.
Note: Mind the safety data sheet when using the adhesive AGOMET® F330.

Step 3/6

Roughen the surfaces slightly and clean them with a non-greasy solvent. Apply the adhesive AGOMET® F330 to the surfaces. Press the second foot piece shell with high pressure.

Step 4/6

After the adhesive has hardened, the leaked adhesive can be filed off.

Step 5/6

Be careful when removing the adhesive in the area of the system stirrup. Do not file predetermined breaking points into the system stirrups. File the anterior edge of the foot piece in order to avoid pressure points.

Step 6/6

The Strong Light orthosis is now finished. As a last step, you need to check its rigidity. You should not be able to move the medial side of the orthosis against the lateral side. If one layer of carbon fibre bands does not seem to be enough, you can now reinforce the carbon fibre bands with additional layers.