*Click on any skill to see where I applied it!
<aside> ✅ Detail-Oriented
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<aside> ✅ Resourcefulness
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<aside> ✅ Commitment
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<aside> ✅ 3D Modelling
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<aside> ✅ 3D Printing
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Trendelenburg gait pattern
<aside> 💡 Our Team’s Objective: Design a hip implant for Art which reduces pain, corrects his gait pattern, and equalizes his legs.
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Using the above information, we first needed to define Art’s condition. The most impactful incident in his life seemed to be the car accident, so my group tried attributing his current symptoms to it. However, I was the only one to notice that the accident had dislocated his left hip, and Art was feeling pain in his right hip! I convinced my group that perhaps the incident was mentioned just to assess our attention to detail. My group started analyzing the given CT scans to find a different condition. Based on the amount of cracks, improper joint fitting, and chronic dislocations, my group characterized it as developmental dysplasia, a condition where the “ball and socket” joint of the hip has not formed properly from birth.
<aside> 🌟 What I Learned: It is important to not “go along with the flow” all the time. “Proofreading” other people’s ideas and letting them know about limitations is crucial.
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CT scan of Art’s right hip. The highlighted area shows the cracks.
CT scan of Art’s right proximal femur. It is evident that the joints do not fit into each other perfectly.
Front X-Ray of Art’s hips. The right hip has moved upwards.
After designing a solution, we had to choose materials for each part of our implant. There were many varieties of materials online, each with their own benefits and drawbacks, and it was difficult to choose. Therefore, I referred to the lecture we had on hip implants in class. I found a direct answer for my patient; considering Art’s active age, it would be best for him to use a combination of ceramic and polyethylene. These materials are wear, corrosion, and scratch resistant. They are able to maintain better contact with surrounding fluids in the body and boast an extremely low fracture ratio of 1:25000!
<aside> 🌟 What I Learned: If it is difficult to do something one way, I should try an alternative method instead of spending a lot of time using the same one.
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Next, we had to think of a solution. My teammates came up with excellent ideas for Art’s specific condition, such as an insert made out of 3D printed bone, and having holes in the implant to allow for bone ingrowth. No one had focused on equalizing the length of his legs. For this, I suggested we could make the hip implant longer than his other leg!
<aside> 🌟 What I Learned: Creativity does not have to mean sophisticated and expensive ways of doing things.
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Proposed ceramic (aluminum oxide) for femoral head of implant
Proposed high-density polyethylene (HDPE) for acetabular cup and liner of implant
Preliminary solid model design with incorrect femoral head angle of 45° from horizontal (actual = 60°)
After choosing materials, we needed to make a prototype. We were given a 3D model of our patient’s femur. I obtained measurements from it and started making the prototype. I had made most of the prototype when I realized that one of my measurements was incorrect, and I couldn’t fix it easily. I remade the entire prototype.
<aside> 🌟 What I Learned: Considering how far I had reached, I could have submitted the prototype as it was. However, high standards should be maintained as much as possible.
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To make the prototype, I needed to measure the femoral head angle in the given 3D bone model (right). However, this was not possible with the standard Measure tool. Instead, I used a unique approach: I created 2 work planes and measured the angle between them!
<aside> 🌟 What I Learned: Advanced CAD tools, such as Offset from plane and Angle to plane around edge.
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Femoral head angle shown in yellow
Once our prototype was ready, we were required to 3D print it!
First, I scaled down the parts simultaneously so that they came on the print bed along with maintaining their fit. Then, I oriented the acetabular cup, liner, and insert in such a manner that, when printed layer by layer from the bottom, no layers would collapse.
After the implant was printed, I noticed many interesting points. First, possibly due to scaling down the piece, the acetabular liner and cup came out as one piece. These pieces had a gap of 0.5 mm between them in the 3D model. The scaling could have also caused the thin, top part of the acetabular insert to consist of small gaps.
<aside> 🌟 What I Learned: Scaling down an object is an efficient method to reduce print time. However, as 3D printers cannot be that accurate on a small scale, some features (e.g., gaps, thickness) may have to be increased.
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Acetabular cup and liner. The holes promote bone ingrowth and keep the implant in place.
Acetabular cup insert. Unique solution for Art which serves as a bridge between the implant and current bone.
Femoral head and stem.