Prosthetic Toe

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One day, I get a phone call from a good friend of mine, their daughter had lost the right large toe in a motorbike accident, what is an engineer to do? The only thing an engineer knows what to do, solve the problem.  

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The challenge was to design and build a prosthetic toe for their daughter in a low cast effective manner to help overcome the trauma. The design needed to be of low complexity to allow future adjustments for manufacture with growth due to the young age of their daughter. 

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Various one to one images were taken of the foot and residual limb which were used as a top and side profile to model the internal profile of prosthesis for conformity to the residual limb. A mirror image of the right toe was used to generate the profile of the prosthesis; an internal joint was added to provide a relative rigidity to the prosthesis. 

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Upon discussions and initial trials, the residual limb was too short to allow for attachment to the foot alone. The prosthesis was then extended to allow the foot to hold the prosthesis onto the residual limb. The supporting robs were profiled such they were hidden on underside edge of the foot. 

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The manufacture consisted of 3D printing the prosthesis in a rigid ABS material that was used as the core of an investment casting process. The two halves of the mould tool were split, the 3D printed component discarded leaving a hollow core cavity creating a mould cast. The rigid joint was then placed inside the casting a silicon poured into the casting to create a silicon prosthesis with an internal rigid joint. 

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The 3D CAD model was parametric and so the profiles could be updated overtime with changed in foot geometry with growth the above processes repeated for manufacture in cost effective manner.

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The aesthetics was managed using Protex Texture paints in collaboration with the Airbrush Venturi network. 

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Safety considerations in all activies and correct PPE can go a long way to preventing these type of injuries not only in the workplace but also in the home.