CAD CAM in Orthotics & Prosthetics

PRPO 200W

what is the tradition workflow / manual process?

negative mold → positive mold → manual manufacturing / fabrication

what is thermoforming?

utilization of thermoplastic materials for device fabrication; materials can be repeatedly softened when heat and hardened when cooled (ice)

what is lamination?

utilization of thermoset materials for device fabrication; material undergoes chemical change to make it permanently insoluble / infusible (egg)

what is CAD?

computer aided design; 2 step process (image capture and model modification)

what is CAM?

computer aided manufacturing; subtractive and additive manufacturing

what is the CAD/CAM workflow?

digital image capture (CAD) → digital model refection (CAD) → manual manufacturing/fabrication or CAM

what are benefits of CAD/CAM in O&P?

• greater precision and improved accuracy

• highly repeatable

• reduction of storage and fabrication space

• consistency and ease of modification

• record for insurance justifications

• clean → no plaster mess or cast saws

• reduced manufacturing complexity

• tracking patient progress over time

• time saving / faster process

what is the workflow of CAD/CAM?

image capture → 3D digital model precisely created → digital model is modified → physical mold is created from the modified digital model (fabricated traditional) → socket, device, or component is fabricated (additive manufacturing, direct machining)

what happens during CAD: image capture?

• digitizer

  • converts historical socket / negative mold into numerable data read by computer

  • data used to create 3D digital image

  • one of the first CAD/CAM technologies in the field

• 3D cameras

  • computerized image taken with scanner

  • digital image created and stored in database

  • can scan patient anatomy directly or from cast taken by hand

what is the structured light systems in CAD: 3D cameras

light patterns projected on object to be scanned, camera record distortion of the light caused by objects

what is the photogrammetry systems CAD: 3D cameras?

generates 3D models with use of high-quality pictures; used in applications built for mobile phones

what is the laser-based systems CAD: 3D cameras?

used time of flight from the scanner to the object to construct 3D model

CAD: by the numbers

• requires extensive, highly precise measurements

• customize existing digital templates to individual measurements

how do you measure circumference?

keep tape measure level; be intentional with tension in tape

how do you measure width or M/L measurement?

• keep M/L gauge level

• insure arms are parallel

how do you measure length?

• insure appropriate tension on tape

• can use meter / yard stick

what is CAD: model modification (rectification)?

design phase; modifications to limb shape and volume to obtain optimal fit and function of device

what is the workflow for CAM: subtractive manufacturing / CNC?

material → subtractive manufacturing → orthosis → lots of waste

what is the workflow for CAM: additive manufacturing / 3D printing?

material → additive manufacturing → 3D printed orthosis → less waste

what is CAM: subtractive manufacturing?

• used to create positive molds

• carving of the rectified model / limb

• uses traditional fabrication methods (thermoform or thermoset)

• direct machining of the materials

• used for fabrication of definitive foot orthotics

• limited by geometry of device (limited axis of movement)

what is CAM: additive manufacturing (AM)?

• 3D printing or AM

• freedom of design → CNC machines are limited by geometry they are able to print

• automation → print devices / sockets without human intervention / overnight

• reduced waste

what is FDM (fused deposition modeling) / FFF (fused filament fabrication)?

based on thermal extrusion: thermoplastic filament is melted and put in the building platform; device is created layer-by-layer

what is SLA (stereolithography) and DLP (digital light processing)?

photo polymerization; first additive process invented: UV laser beam solidifies a liquid resin

what is SLS (selective laser sintering)?

a 3D printing technology that utilizes laser melting: laser selectively melts the powder to form the solid part

what is inkjet or binder jetting?

like SLS but instead a liquid binding material is selectively dropped into the powder bed

what is partial hand protocol?

• clinician takes high resolution silicone impression of affected side

• scanning patient directly is challenging due to motion in fingers

• scanning plaster model eliminates errors from motion

model scanned with 3D scanner

• scan creates digital model of limb

  • permanent patient record

  • precisely modify model to create modification standards

  • utilize software to modify

design prosthetics inner and outer finger socket from 3D model

• custom trim lines

• precisely socket thickness and bevel trim lines

• create flexible inner and rigid outer from same 3D model

• add precise pressure points within socket

print modified model of finger

• digitally modify model to specifications

• modified shell of model printed

• pour shell to include pipe for fabrications

• fabricate silicone directly over 3D printed model

  • no dehydration of model needed

  • very smooth inner surface

print inner and outer socket simultaneously in form lab SLA printers

• significantly reduce labor

• print during non working hours

• can print 16-20 sockets at a time

• 8-12 hour print time depending on resolution settings

check socket design

• flexible resin to simulate silicone socket for trail fitting

  • multiple thickness inner sockets can be made and interchangeable at fitting to precisely manage volume

  • rigid clear resin simulates carbon frame

check socket fitting and alignment

• clinician evaluates fit and trim lines

• clinician mounts finger base in proper alignment

alignment transfer and finish

• 3D printed socket is placed in custom designed finger transfer jig

• silicone socket made to color specified on work order

• carbon frame made and placed in alignment jig to transfer alignment

• final carbon layer applied

• prosthesis finished, assembled and shipped to clinician for delivery