Total hip acetabular cup flange design and its effect on cement fixation

Area of Science:

• Biomaterials Engineering
• Orthopedic Surgery
• Medical Device Design

Background:

• Acetabular cup fixation is crucial for total hip arthroplasty (THA) success.
• Cement fixation is influenced by the design of the acetabular cup surface.
• Optimizing cup design can enhance implant stability and longevity.

Purpose of the Study:

• To investigate the impact of acetabular cup flange and pod designs on cement fixation during THA.
• To compare the cement intrusion pressures and depths for different flange designs.
• To evaluate the effect of cup design on cement mantle formation and cup positioning.

Main Methods:

• Four acetabular cup designs with varying flanges (none, 12-scallop, 3-scallop, continuous) were tested.
• Cups were inserted into simulated and cadaver acetabula using an MTS machine.
• Polymethylmethacrylate (PMMA) intrusion pressure and depth were measured using transducers and rheometers.
• Cement mantle shape was analyzed after manual insertion into cadaver acetabula.

Main Results:

• A continuous flange design resulted in significantly higher PMMA intrusion pressures and depths compared to other designs.
• Cups with pods and a continuous flange achieved concentric positioning.
• A uniform cement thickness was observed around the cup, with good containment within the acetabulum.

Conclusions:

• Acetabular cup design, specifically the presence of a continuous flange, significantly impacts cement fixation in THA.
• Continuous flanges enhance cement intrusion and promote optimal cup positioning and cement mantle formation.
• This design modification holds potential for improving the stability and success of cemented THA procedures.