Reliable Outcomes of Fixed Lateral UKR After Medial Mobile-Bearing UKR

Overview

This study reports 5-year outcomes of Fixed Lateral Oxford Unicompartmental Knee Replacement (FLO) used as a staged bi-compartmental procedure following medial mobile-bearing UKR. Results demonstrate significant functional improvement, low complication rates, and excellent implant survival, supporting FLO as a reliable alternative to total knee replacement (TKR) in lateral compartment osteoarthritis progression.

Background

Medial unicompartmental knee replacement (UKR) is a common treatment for medial compartment osteoarthritis, offering faster recovery and better function than total knee replacement (TKR). However, lateral compartment osteoarthritis is the most frequent cause of revision after medial UKR. While TKR is the standard revision, staged bi-compartmental UKR with retention of a well-functioning medial UKR is an alternative with less intraoperative risk. The Fixed Lateral Oxford UKR (FLO) was introduced to reduce dislocation risk seen with mobile-bearing lateral UKRs and is increasingly used in staged bi-UKR procedures.

Data Highlights

Key Findings

• 44 patients with medial mobile-bearing UKR underwent staged lateral FLO for severe lateral osteoarthritis or avascular necrosis.
• No intraoperative or medical complications, readmissions, or early mortality were reported.
• Only one re-operation occurred due to medial bearing dislocation 1.4 years post-FLO, successfully managed with bearing exchange.
• Significant improvements in Oxford Knee Scores and Tegner Activity Scores were observed postoperatively at 1, 2, 5, and 7 years.
• Survival analysis showed excellent implant longevity with no conversions of the lateral UKR to TKR.
• Patellofemoral joint degeneration was not a contraindication, with many patients having exposed bone in this compartment.

Clinical Implications

The FLO implant provides a safe and effective option for patients with lateral compartment osteoarthritis progression following medial UKR, avoiding the higher risks associated with TKR revision. Surgeons can consider staged bi-compartmental UKR with FLO to restore knee function and alignment while preserving native knee kinematics. Close monitoring for medial bearing dislocation is warranted, but overall complication rates are low.

Conclusion

Fixed Lateral Oxford UKR used as a staged bi-compartmental procedure after medial mobile-bearing UKR yields reliable mid-term outcomes with low complication and revision rates. This approach represents a viable alternative to total knee replacement for lateral compartment osteoarthritis progression.

References

1. Pandit et al. 2015 -- Outcomes of staged bi-compartmental UKR
2. National Joint Registry UK -- Annual Report
3. Oxford Knee Group -- Medial and Lateral UKR outcomes