In vitro evaluation of acetabular host bone coverage and cemented cup stability in total hip arthroplasty

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Biomaterials science

Background:

• Determining optimal host bone coverage for initial cement cup fixation is critical for implant longevity.
• Previous studies have not definitively established the precise bone coverage percentage required for adequate initial fixation.

Purpose of the Study:

• To investigate the relationship between acetabular host bone coverage and the initial fixation strength of cemented cups.
• To evaluate how different degrees of bone coverage affect the stability of total hip arthroplasty components.

Main Methods:

• Utilized three defect models and two reconstructed models with varying cup center-edge angles (-10°, -5°, 0°) to simulate minimum fixation conditions.
• Assessed initial cup stability using cyclic loading tests for one million cycles, measuring vertical displacement of the femoral head.

Main Results:

• Vertical displacement of the femoral head increased as the cup center-edge angle decreased from 0° to -10°.
• The greatest vertical displacement was observed at -10°, while the least was at 0°, indicating superior stability with greater coverage.
• Statistical significance (P < 0.05) was found in all model comparisons.

Conclusions:

• Acetabular host bone coverage significantly impacts the initial stability of cemented acetabular cups.
• Clinical practice should aim for a cup center-edge angle >0° to ensure robust long-term stability in primary total hip arthroplasty.