The objective of this project is to investigate existing bone screw properties to design an acetabular cup stabilization bone screw for total hip replacement patients with osteoporosis and consequently decreased bone density.
Sponsored by: Stryker
Team Members
Davina Stamp Andrew LaTourette Gashema Theophile Jinwen Gao
Instructor: Lyndsey Hylbert
Project Poster
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Project Video
Project Summary
Overview
Stryker is an influential medical technology company most known for its innovative devices employed in orthopedic surgeries, including the focus of our project: the total hip replacement interfemoral implant and acetabular cup assembly. Stryker has tasked our team with designing, prototyping, and testing a novel osteoporotic bone screw for securing the acetabular cup to the pelvic bone for osteoporotic total hip replacement surgery patients. The screw was designed to promote bone purchase and maximize the stability of the acetabular cupin low-density bone, without causing damage to thebone through use or in the case of a surgical revision.
Objectives
– Selecting bio-inert, non-toxic materials
– Minimizing the insertion torque
– Maximizing unscrewing resistance
– Maximizing axial pullout force
– Maximizing torque required for removal
– Maximizing acetabular cup stability and resistance to sliding motion
– Increasing resistance to multiaxial stresses
– Minimizing insertional and revisional bone damage
Approach
– Researching the biocompatibility and mechanical properties of various materials to determine the material and potential manufacturing methods
– Investigated thread form, tip, head, and shaft geometric properties in existing bone screws and comparative research for low-density bone security without excess damage
– Conducting axial pullout strength, toggling damage, and insertional torque testing with prototypes and compared results to traditional screws
Outcomes
The final design employs:
– A conical shaft that creates press-fit forces for greater security and eliminates degradative bone-shielding phenomena
– A DC/DT thread form pattern that creates more defined threads in bone material and reduces bone displacement and damage during implantation
– A curved-thread geometry that maximizes force for axial pullout and reduces damage due to toggling and lateral force application
– Maximum insertion torque of 23 in-lband maximum pullout force of 400-600N
– Bio-inert material and manufacturing for long-termbone health and regrowth
K-12 Materials
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