Design changes improve contact patterns and articular surface damage in total knee arthroplasty

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Materials science

Background:

• The Optetrak PS posterior stabilized knee replacement has been effective since 1995.
• In 2009, the Optetrak Logic was introduced with design modifications to reduce edge loading on the tibial post.

Purpose of the Study:

• To provide the rationale for the Optetrak Logic design change.
• To compare post damage between the Optetrak PS and Optetrak Logic designs.

Main Methods:

• Retrieval findings of tibial post damage were integrated with finite element analysis.
• A 3:1 matched sample of 60 PS and 20 Logic inserts were analyzed for polyethylene damage.

Main Results:

• Incorporating rounded contact geometries markedly reduced polyethylene stresses.
• The redesigned Optetrak Logic showed reduced surface damage and deformation on the tibial post compared to the original design.

Conclusions:

• The study demonstrates a design cycle using retrieval analysis and analytical tools to improve implant performance.
• Design changes to the post-box geometry have markedly reduced anterior post damage in posterior stabilized knee replacements.