Captain America’s best friend, Bucky Barnes, suffered a traumatic fall from a train and lost his arm. The arm was replaced with a bionic arm, and Bucky was brainwashed into being an evil super soldier. Clearly, there was a lot of oversight by biomaterials experts on the design of Bucky’s bionic prosthetic arm! Let’s see if we can understand a little bit of their work!

a)Notice how the arm attaches to the remaining viable tissue of the body.

Do you think this design is feasible from a biomaterials and medical/surgical perspective? Describe some issues that might arise and why? Remember that this design is being ‘internally’ integrated into the body and is not simply a prosthetic.

b) The bionic arm allows Bucky to have super strength, and it withstands high stresses. During a fight with Cap, Bucky falls from a tower and breaks his fall by landing on his arm.

(i) Draw the forces associated with an impact with the ground after dropping from 40 feet (~12m). Assume the arm to be a solid cylinder contacting the ground perfectly straight.

(ii) Calculate the force of impact (use conservation of energy) with the following parameters: Bucky is 5’9” and 160 lbs (~75 kg) The dirt that Bucky lands on ‘gives’ 1 cm Hint: the force of impact is associated with the work done on the ground/dirt

c) Bone has a yield strength of ~110 MPa and an ultimate compressive strength of 190 MPa. In the above situation, would the bone in a normal arm break? What’s an even more likely injury to result?

d) From the following chart, which materials should be considered for the bionic arm? Why?

NOT to scale relative Stress vs. Strain plot for the following materials:

1. Alumina

2. Co-Cr-Mo alloy

3. Stainless Steel

4. Titanium

5. Cortical Bone (compact bone, structural properties)

6. Matrix polymers

7. PMMA

8. Polyethylene

9. Spongy Bone (joints, ends of long bones)

10. Tendon/ligament

11. Cartilage

e) What other biomaterials-related considerations must be met by this bionic arm implant?

f) Poisson’s ratio for bone is ~0.6 and is ~0.3 for metals. Explore the possible outcomes of this mismatch in properties.

g)Bone is made up of two tissues: cortical bone and cancellous bone.

Mineral (hydroxyapatite) is the main determinant of the elastic modulus. Cancellous bone is 25% as dense, 10% as stiff, and 500% as ductile as cortical bone. Draw a nominal stress/strain relationship for the two tissues on the same plot. Stiffness = k =AE / l, where A is cross-sectional area, l is length

h)Let’s say you work for a company developing the next generation of prostheses and biomechanical implants. In a futuristic take on Bucky’s arm (say you have the next five years to design, refine, and produce the prosthetic implant), what would you design? Are these things currently feasible? What biomaterials would you use to make these designs a reality?

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Answer rating: 100% (QA)

A Integrating a bionic arm internally into the frame is a complicated project from both a biomaterials and clinicalsurgical attitude Some issues that might rise up include Biocompatibility The materia... View the full answer