Retrieval Analysis of Polyethylene Components in Rotating Hinge Knee Arthroplasty Implants

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Implant retrieval analysis

Background:

• Retrieved rotating hinge (RH) total knee arthroplasty (TKA) implants from four manufacturers were analyzed.
• Focus was placed on surface damage to polyethylene components.

Purpose of the Study:

• To determine if differences in polyethylene damage exist among four RH TKA designs.
• To investigate if design characteristics explain observed polyethylene damage differences.

Main Methods:

• Seventy-two RH implants (DePuy, Zimmer, Stryker, Biomet) revised between 2002-2017 were assessed.
• Polyethylene surface damage was evaluated using a subjective grading system across multiple zones.
• Design characteristics analyzed included dwell point location, axle position, and range of motion allowances.

Main Results:

• No significant differences in total polyethylene damage scores were found among the four implant designs (P = .45).
• Stryker Howmedica MRH implants had less backside wear but more articular-sided wear compared to some other designs.
• Increased damage scores were observed in implants revised for mechanical reasons and those with longer implantation duration, except for NexGen implants.

Conclusions:

• No single RH TKA design demonstrated superiority in minimizing overall polyethylene wear damage.
• Polyethylene damage severity was not significantly different across the analyzed RH implant designs.
• Current RH designs do not offer a clear advantage in mitigating articular surface wear.