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Effect of locking mechanism on fluid and particle flow through modular acetabular components
C Khalily1, M G Tanner, V G Williams
1Biomechanical Research Laboratory, Missouri Bone and Joint Center, Barnes-Jewish West County Hospital, St. Louis 63141, USA.
The Journal of Arthroplasty
|May 20, 1998
Summary
Screw holes in acetabular components can allow fluid and debris to reach bone stock. Specialized seals, like the Micro-Seal cup, effectively prevent this particle migration during hip implant use.
Area of Science:
- Orthopaedic biomechanics
- Biomaterials science
- Implant technology
Background:
- Acetabular components in hip replacements are susceptible to fluid and debris ingress.
- Screw holes in acetabular shells may compromise the seal between the implant and bone stock.
Purpose of the Study:
- To investigate if screw holes in modular acetabular components facilitate fluid and debris migration into the acetabular bone stock.
- To evaluate the efficacy of different sealing mechanisms in preventing such ingress.
Main Methods:
- Six modular acetabular components were tested in a sealed chamber under simulated physiological loading conditions (axial and torsional).
- Polystyrene microspheres in water were applied above the components, with potential pathways including the cup-liner interface and screw holes.
- Fluid and debris below the component were collected after 1 million cycles and analyzed for microspheres using electron microscopy.
Main Results:
- Fluid and microspheres were detected in the collection chamber for most tested components with screw holes.
- The Reflection cup with a screw hole cover did not prevent fluid and debris flow.
- The Micro-Seal cup, featuring a peripheral seal, successfully prevented fluid and particle migration.
Conclusions:
- Screw holes in acetabular shells represent a potential pathway for fluid and debris ingress into the bone stock.
- Peripheral seals around the acetabular component rim are effective in preventing adverse particle migration.