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[Thread design of screw-in acetabulum prostheses].
H Effenberger1, M Imhof, U Witzel
1Institut für Konstruktionstechnik, Fakultät für Maschinenbau, Forschungsgruppe für Biomechanik, Ruhr-Universität Bochum, Deutschland. H.Effenberger@telering.at
Zeitschrift Fur Orthopadie Und Ihre Grenzgebiete
|October 19, 2001
Summary
This study systematically classified threaded cup designs, revealing significant variations in thread patterns. Modern designs feature narrower V-cut or flat threads with specific depths, turns, and pitch for optimal performance.
Area of Science:
- Orthopedic implant design
- Biomedical engineering
- Materials science
Background:
- Thread design is critical for the screw-in behavior and positioning of threaded cups.
- A systematic classification of existing thread designs is currently lacking.
Purpose of the Study:
- To systematically classify and analyze the thread designs of first and second-generation threaded cups.
- To evaluate key thread parameters influencing implant performance.
Main Methods:
- Analysis of 10 first-generation and 27 second-generation threaded cups.
- Utilized a tool setter and no-touch light section technique.
- Evaluated parameters: thread shape, pitch, number of turns, rows of teeth, tooth length, and shape.
Main Results:
- First-generation threads were V-cut or saw-shaped, with an average depth of 3.1 mm and 1-7 turns.
- Second-generation threads (V-cut, saw, or flat) averaged 3 mm depth, with 2-5 turns.
- Significant variation in thread parameters (depth, width, pitch, turns, teeth rows) observed across both generations.
Conclusions:
- Numerous distinct thread patterns exist with highly variable parameters.
- Contemporary threaded cups predominantly use narrow V-cut, saw-shaped, or flat threads.
- Modern designs typically feature depths up to 3 mm, a maximum of 5 turns, and pitch values around 4.5 mm.