Case Study: 3D Printed Orthopedic / Bio-Medical Hand Cast

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Introduction  

206, It is the number of bones a normal human has. Bones are the strongest part of the body. Bones are the core of the body which gives strength and ability to lift weights. Bones absorb the external force to protect our internal organs. But sometimes accidentally bones fractured. As per surveys conducted, over a quarter of a million Indians break a bone and seek orthopedic medication annually. Coupled with this, reports also put light into the fact that cases for fractured bones and osteoarthritis in India may shoot to 60 million by 2025.  In comparison to western counterparts, Indians are more prone to fractures at their early ages which have caught serious attention in the healthcare industry. Consequently, the dire need for technological advancements in medical science multiplies exponentially each year. Besides, the Indian dynamic prosthetic device market is estimated to be over USD 450 million growing at a rapid pace of 30% per annum to reach USD 3 Billion shortly.

Wrist Fractures: Colles and Smith

Traditional Orthopedic Plaster Cast

The healing process of bone is very slow and takes a long time. For that, we have to minimize the motion of broken bone so that it perfectly joint. Normally we used an orthopedic cast to stabilize and restrict the motion of fractured bone. Currently casting methods are rudimentary and use a soft inner cotton layer together with a hard-outer plaster or fiberglass layer. Although effective in healing, these casts list several limitations. One of the prominent challenges of traditional orthopedic casts is its weight. That is to say, these casts are bulky and often feel uncomfortable when used for a long period. Also, the eventual formation of moisture inside the cast leads to itchiness and skin irritation. Most importantly, plaster casts are not waterproof and heavily interrupt the healing process.

Traditional orthopedic plaster

Process of 3D Printed Cast

A group of last year biomedical students from LD engineering college, Ahmedabad wanted to solve this problem with the help of 3d printing technology. They want to make a wrist fracture cast but they don’t know how to proceed. We wanted to guide them in right direction.

1.       3D Scanning 

We all know about normal scanning or 2d paper scanning. In 2d scanning, we copied image, text, etc. in softcopy format. With the help of softcopy, we can edit or modify the data. But in 3d scanning, we used a 3d scanner. With the help of a 3d scanner, we scan 3 dimensional (3D) object and get 3d scan data. Which we can edit and modify.

With the help of 3d scanner, we scan the wrist from all 3600 angles. Now we have the accurate dimension of the wrist. 3d scanning is important because everybody has a different size and shape of the wrist. The different patient has a different size so we have to scan their wrist if we want to make 3d printed plaster for them.

3D Scanner

The actual scan hand data from 3d scanner

2.     Design

getting 3d scan data of hand. We used it as a reference and start wrist hand-cast design. We planned wrist cast plaster in 2 sections so it can easily fit and remove from hand. We try to reduce weight as much as possible without compromising strength. To do that we make holes in the design. It gives us another advantage of air circulation. Which is one of the specialties of 3d printed hand-cast Design and modification took around 10 – 12 hours.

Design of wrist hand cast

3.     3D Printing

Before going to 3d printing first, we to prepare a model for 3d printing. To do that, we have to input design in slicing software. In the slicing software, we create support for the overhang section of the model. We tried to reduce support so to do that, we give the model a proper orientation. To achieve a good surface finish, we set a layer height 0.2mm. Now model was ready for 3d printing. We transferred the slicing file in the printer and loaded material. It took 14 hours to print.

3D Print                                     vs                                          3D Design

Conclusion

3D printed cast is lightweight in comparison to traditional plaster cast and takes exact shape and contour of injured bone. 3d printed cast gives proper air circulation, pressure balance reduces the risk of infection, muscle relaxation, sweat, and odor mitigation. It is waterproof. It is too easy to apply or remove from the patient.