Incomplete seating of the liner with the Trident acetabular system: a cause for concern?

Area of Science:

• Orthopedic Surgery
• Biomaterials Engineering
• Radiology

Background:

• The Trident acetabular shell with a metal-backed alumina liner is used in primary total hip replacement.
• Proper seating of the liner is crucial for implant stability and function.

Purpose of the Study:

• To evaluate the incidence and potential causes of incomplete liner seating in the Trident acetabular component post-total hip replacement.

Main Methods:

• Retrospective review of initial post-operative radiographs (anteroposterior and lateral) for 117 hips (113 patients) using the Trident acetabular shell and metal-backed alumina liner.
• Assessment of liner seating based on radiographic evidence.

Main Results:

• Incomplete liner seating was observed in 19 out of 117 hips (16.4%).
• One case of complete liner dissociation requiring revision was noted but excluded from prevalence.
• One mis-seated liner was revised early, and two initially incompletely seated liners corrected on follow-up.

Conclusions:

• A significant percentage of Trident acetabular components exhibit incomplete liner seating, potentially impacting hip replacement outcomes.
• Possible contributing factors include surgical technique and potential deformation of the Trident shell upon implantation.
• Surgeons should be aware of these technical considerations and the possibility of shell deformation during implantation.