An all-polyethylene cementless tibial component. A five- to nine-year follow-up study

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Medical Device Engineering

Background:

• Total knee arthroplasty (TKA) is a common procedure for end-stage knee osteoarthritis.
• Cementless fixation aims to improve long-term implant stability and reduce complications associated with bone cement.
• All-polyethylene tibial components offer potential advantages in terms of bone preservation and surgical simplicity.

Purpose of the Study:

• To evaluate the long-term survivorship and failure modes of an all-polyethylene cementless tibial component in total knee arthroplasties.
• To identify potential concerns related to the performance and wear characteristics of this specific implant design.

Main Methods:

• A retrospective analysis of 221 total knee arthroplasties utilizing an all-polyethylene cementless tibial component.
• Follow-up duration ranged from seven to nine years, assessing implant survival and failure mechanisms.
• Examination of failed components for evidence of polyethylene abrasion and component subsidence.

Main Results:

• The overall survivorship of the cementless tibial component was 87.1% at seven to nine years.
• Implant failures, characterized by medial subsidence, primarily occurred after three years.
• Abrasion of the polyethylene on the undersurface was observed in all failed components, indicating susceptibility to shearing forces.

Conclusions:

• Flexible, cementless all-polyethylene tibial components can achieve acceptable long-term function across various bone types.
• Polyethylene abrasion resulting from shearing forces represents a critical failure mode that necessitates design modifications.
• Future component designs should incorporate features to mitigate shearing or employ surface treatments to enhance abrasion resistance.