Functional performance of mobile versus fixed bearing total knee prostheses: a randomised controlled trial

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering

Background:

• Total knee arthroplasty (TKA) aims to restore function and alleviate pain.
• Mobile bearing and fixed bearing designs are common TKA components, each with theoretical advantages.
• Assessing functional outcomes is crucial for understanding the clinical efficacy of different TKA designs.

Purpose of the Study:

• To compare active flexion between mobile bearing and fixed bearing cruciate retaining total knee arthroplasty.
• To evaluate differences in passive flexion and Knee Society Score (KSS) between the two bearing types.
• To provide evidence for clinical decision-making in total knee replacement surgery.

Main Methods:

• A randomized controlled multi-center trial was conducted.
• Participants were allocated to either mobile bearing or fixed bearing TKA groups.
• Active and passive flexion, along with Knee Society Score (KSS), were assessed preoperatively and at 3, 6, and 12 months postoperatively.

Main Results:

• Active flexion was similar between mobile (99.9°) and fixed bearing (101°) groups.
• Clinical Knee Society Scores (KSS) were comparable between the mobile (90.0) and fixed bearing (92.4) groups.
• A statistically significant difference favoring the fixed bearing design was observed in the functional KSS stair climbing subscore at 3 and 12 months.

Conclusions:

• No significant short-term differences in active flexion were observed between mobile and fixed bearing TKA.
• While active flexion was comparable, functional outcomes related to stair climbing showed a slight advantage for the fixed bearing design.
• Further long-term studies may be warranted to fully elucidate functional differences between TKA bearing types.