Notes on the assembly of the Dudley Childress 3 (DC3 Prosthesis)

Disclaimer: The information provided on this webpage, including video tutorials and tool lists, is intended for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Assembling a prosthetic device like the Dudley Childress 3 (DC3) Prosthesis requires specialized training and expertise. The process involves the use of materials and tools that could be hazardous if improperly handled. Always follow safety guidelines, including the use of appropriate personal protective equipment like FFP3 dust masks. We strongly recommend consulting with certified prosthetists and orthotists or other qualified healthcare providers before attempting to assemble or modify any prosthetic components. Failure to do so could result in injury or adverse effects. Legs4Africa assumes no responsibility for any damages or injuries incurred as a result of using the information on this webpage.

Tool List

This list does not cover the basic hand and machine tools necessary for assembly – rather the tools likely to be missing from a moderately well-equipped P&O workshop.

• Grit edged jigsaw blades, and jigsaw.  This is used for cutting the FR4 fibreglass sole plate material.

• Electric Staple gun, able to fire 20mm long staples.

• FFP3 dust mask.  ALWAYS use a dust mask when cutting and or grinding FR4 fibreglass laminated epoxy plate – the sole plate of the DC3 prosthesis.

Step 1 – Preparing the footplates

Step 2 – Attaching the footplates to the keel

Step 3 – Preparing the foot shell template

Step 4 – Preparing the foot shell

Step 5 – Moulding the foot shell to the last

Step 6 – Making the foot shell soles

Step 7 – Finishing the foot shell

Keel Modifications

For most patients, grinding the anterior plantar surface of the keel block will be preferable to increase available dorsiflexion.  

Material should be removed from the hatched area shown in the photo above.  Removal of material here increases the length of the foot plate lever arm from the forefoot fulcrum – the point at which the green keel block contacts the foot plate.  This increase in lever arm length decreases the force necessary to achieve increased dorsiflexion of the foot ankle complex. Remember.  It is a simple matter to remove more material.  Once removed material cannot be replaced.  Removal of material here should be optimised during a dynamic assessment process, based at least partially on feedback gathered form the patient.

Last Preparation

The wooden foot last – used to produce the outline for the sole plate and to form the foot shell upper – should be 5-10 mm smaller in every dimension than the final foot size.

It will be necessary to remove 10mm of material from the plantar surface of the last/foot model to provide space for the sole unit and filler.  This material can be removed with a bandsaw, and then ground flat to create a planar surface.  The sole outline created here is the outline of the sole plate – to be transferred to the FR4 fibreglass sheet.