Posterior Stabilized Polyethylene Inserts in Total Knee Arthroplasty: A Retrieval Study Comparing Conventional to High-Flexion Designs.

Background: High-flex (HF) total knee arthroplasties are modified posterior-stabilized (PS) implants designed to accommodate greater flexion.

Methods: We examined differences between HF and PS retrieved tibial inserts with regard to polyethylene surface damage. Twenty HF inserts from each of 3 manufacturers were matched using patient demographics with 20 PS inserts from the same manufacturers. Ranges of motion between matched patients were not different.

Results: Based on subjective damage scores, no differences were detected between HF and PS groups. Differences were found, however, among manufacturers, consistent with design approaches taken for PS and HF implants.

Conclusion: In our series, high flexion did not influence damage, although this was likely influenced by the fact that few HF patients in our study had larger range of motions than their PS counterparts.