Objective:

To compare the mid-term efficacy and cost-effectiveness of unicompartmental knee arthroplasty using a Mobile-Bearing and a Fixed-Bearing in elderly patients with knee osteoarthritis.

Approach:

• Study Design: Multicenter retrospective cohort study involving 502 patients who underwent surgery at four joint centers from July 2020 to July 2023.
• Patient Grouping: Patients were divided into a Mobile-Bearing Group (n = 251) and a Fixed-Bearing Group (n = 251) based on the type of prosthesis used.
• Outcome Measures: Comparison of surgical parameters, visual analog pain scores, knee joint scores, joint range of motion, imaging parameters, complications, and cost-effectiveness.

Key Findings:

• The surgical time of the Mobile-Bearing Group was longer than that of the Fixed-Bearing Group (P < 0.001).
• VAS scores were significantly lower in the Mobile-Bearing Group during mid-term follow-up (6 months to 2 years).
• HSS scores, joint range of motion, and hip knee ankle angles were significantly higher in the Mobile-Bearing Group (P < 0.05).
• There was a higher incidence of liner dislocation in the Mobile-Bearing Group.
• The Fixed-Bearing Group showed an increasing trend of progressive wear in the contralateral compartment.
• The Mobile-Bearing Group had higher direct medical costs but obtained more quality adjusted life years.

Interpretation:

Mobile-Bearing unicompartmental arthroplasty provides better pain relief and functional recovery in the mid-term but incurs higher costs and specific complication risks compared to Fixed-Bearing unicompartmental arthroplasty, which is more economical.

Limitations:

• Retrospective design may introduce selection bias.
• Lack of long-term follow-up data beyond 2 years.

Conclusion:

Mobile-Bearing unicompartmental arthroplasty offers superior mid-term outcomes but incurs higher costs, while Fixed-Bearing is a more cost-effective option.