Rotating-platform has no surface damage advantage over fixed-bearing TKA.

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Wear Analysis

Background:

• Clinical studies show no advantage of rotating-platform total knee arthroplasty (TKA) over fixed-bearing TKA.
• This study compares wear damage between design-matched rotating-platform and fixed-bearing TKAs with similar condylar geometry.

Purpose of the Study:

• To determine if rotating platforms exhibit less severe damage due to conforming articulation.
• To compare damage location and characteristics on tibiofemoral and backside surfaces.
• To assess differences in combined damage and deformation (thickness) between designs.

Main Methods:

• Damage grading and mapping performed on 25 rotating-platform and 17 fixed-bearing inserts.
• Laser scanning used to obtain insert thicknesses and 3D scans of inferior surfaces for dimensional change analysis.
• Comparable patient demographic data between cohorts.

Main Results:

• Similar tibiofemoral damage scores for both rotating-platform and fixed-bearing inserts.
• Greater backside damage scores on rotating platforms, primarily due to third-body debris scratching.
• Increased surface area of damage on rotating platforms; no significant difference in insert thickness between designs.

Conclusions:

• Rotating-platform TKAs exhibit increased total damage scores on the backside.
• The propensity for third-body debris and larger damaged surface area indicate no wear advantage for this mobile-bearing design.
• Findings suggest fixed-bearing designs may offer comparable or superior wear performance.