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Unformatted text preview: w of a bicondylar knee prosthesis. Rf, Rt are the radii of the metal femoral (white) and
plastic tibial (shaded) components, respectively; t is the average thickness of the plastic tibial component. Page 4 of 10 ME/BioE C176 Final Exam, Spring 2001 Name:__________________________________ 3. Implant Failure Analysis [30 points total]
As an expert biomechanical engineer, you are consulting on a legal case. You have been asked to determine
if a material defect was to blame for a failed implant. Here are the facts of the case:
• • • • A large young man (130 kg body mass, 2 m tall, 24 years old) accidentally stepped over a retaining wall
while on a ski trip in Lake Tahoe. Upon landing, he felt a sudden pain in his weight-bearing leg.
Subsequent radiographs showed a fracture of an intramedullary (IM) rod, half way along its length.
The rod had been implanted eight months previously, and was pinned at each end.
After visiting the site of the accident, you determined that the retaining wall was one meter high. You
also found out from the medical records and radiographs that the IM rod had a hollow circular crosssection, inner and outer diameters of 7 and 13 mm, respectively; the corresponding inner and outer
diameters of the bone at the cross-section of implant failure were 14 and 28 mm, respectively. The bone
appeared fully healed from the previous fracture that ha...
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- Fall '10