The dual radius hemispherical 'Trident" cup: results based on 150 consecutive cases.

Area of Science:

• Orthopedic Surgery
• Biomaterials Engineering
• Medical Device Design

Background:

• Achieving initial stability in press-fit acetabular cups is crucial for successful total hip replacement (THR).
• Dual-radius press-fit cups, with a larger equatorial diameter, offer a method to enhance press-fit and ensure stability for bone ingrowth.
• Various techniques like line-to-line fit and screw fixation exist, but dual-radius designs aim for reliable initial stability.

Purpose of the Study:

• To evaluate the clinical performance and initial stability of the dual-radius Trident AD acetabular shell in primary total hip replacements.
• To assess the bony incorporation and radiographic evidence of loosening or radiolucency of the Trident cup.
• To determine if the Trident cup is a suitable option for acetabular replacement surgery.

Main Methods:

• A retrospective review of the first 150 consecutive primary total hip replacements (THRs) using the Trident AD shell (Stryker Orthopaedics) was conducted.
• The study period was from January 2002 to January 2008.
• Data collected included patient follow-up duration, post-operative Harris Hip Scores, and radiographic assessments for bony incorporation and loosening.

Main Results:

• The median follow-up duration was 6.2 years (range, 5-7 years).
• The median post-operative Harris Hip Score was 90.5 (range, 51-98).
• All components showed bony incorporation, with no definite radiographic loosening or signs of radiolucency at the latest follow-up.

Conclusions:

• The Trident dual-radius acetabular cup demonstrates encouraging results in primary total hip replacement.
• The component achieved reliable initial stability and excellent bony incorporation.
• The Trident cup is considered a valid and effective choice for acetabular replacement, with no evidence of mechanical failure within the study period.