Backside damage corresponding to articular damage in retrieved tibial polyethylene inserts

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Mechanical Engineering

Background:

• Backside wear of polyethylene inserts in total knee replacements is a concern.
• Articular contact stresses and kinematic conditions are potential contributors to backside wear, alongside insert-baseplate motion.
• Limited data exists comparing articular and backside damage patterns.

Purpose of the Study:

• To investigate the effect of physiologic loading on the modular capture mechanism of tibial components.
• To analyze the distribution and patterns of articular and backside surface damage on retrieved tibial components.
• To correlate insert motion with backside damage.

Main Methods:

• Evaluation of damage patterns on 37 retrieved tibial inserts with a full peripheral rim capture mechanism.
• Inclusion of six autopsy-retrieved components for mechanical testing.
• Assessment of the duration of physiologic loading and its impact on the capture mechanism and damage.

Main Results:

• Physiologic loading duration influenced the modular capture mechanism and damage patterns.
• Backside damage indicated a mechanical interlock between the polyethylene insert and tibial tray, correlating with insert motion.
• Retrieved inserts with less motion showed longer in vivo function and larger backside damage areas.
• Backside damage patterns corresponded to articular damage, concentrated on the posterior insert half.

Conclusions:

• Distinct wear mechanisms operate at the articular and backside interfaces of tibial components during physiologic loading.
• Insert motion and physiologic loading duration are critical factors affecting backside damage.
• The study highlights the complex interplay between component design, loading conditions, and wear in total knee arthroplasty.