Summary

This case report describes catastrophic failure of an Oxinium knee implant due to polyethylene wear, edge loading, and metallosis, highlighting the importance of surgical precision, vigilant follow-up, and early intervention to prevent severe complications in patients with oxidized zirconium prostheses.

Abstract

Title:
Catastrophic Full Thickness Wear of Oxinium Knee Implants: A Case Report and Analysis of Failure Mechanisms

Background

Oxinium (oxidized zirconium) implants have been developed to improve wear resistance in knee arthroplasty, especially for patients with metal hypersensitivity. Despite their advantages, cases of catastrophic wear have emerged, raising concerns about long-term durability and implant failure.

Case Report:
A 63-year-old female, nine years post-bilateral knee arthroplasty with oxinium implants, presented with progressive pain and instability in her right knee. Symptoms began two years post-surgery and worsened over time. Radiographs showed narrowing of the medial joint space and metal debris, indicative of metallosis. During revision surgery, extensive polyethylene wear was discovered, causing edge loading of the femoral component against the tibial tray, which scratched the oxinium surface and exposed the underlying soft zirconium alloy. This led to significant metallosis, resulting in synovial inflammation and bone loss. The revision was successfully performed using a higher-constrained implant, and the patient showed good postoperative recovery with improved range of motion and stability.

Analysis of Failure Mechanisms:
The failure was attributed to:
1. Polyethylene Wear: Deterioration of the polyethylene insert led to metal-on-metal articulation.
2. Edge Loading and Scratching of Oxinium Surface: Scratching of the oxinium surface exposed the softer zirconium alloy, accelerating wear.
3. Metallosis: The metal debris triggered inflammatory responses, leading to implant loosening.
4. Surgical Technique and Implant Design: Factors like improper seating of the polyethylene or unbalanced joint gaps may have contributed to early failure.

Conclusion

This case highlights the risk of catastrophic failure in oxinium knee implants due to polyethylene wear, edge loading, and metallosis. Surgeons should ensure meticulous surgical technique, frequent radiographic follow-up, and early intervention to prevent severe damage. Further studies are needed to enhance the design and durability of these implants.