Mobile-bearing knee replacement: concepts and results.

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Materials science

Background:

• Total knee replacements (TKRs) are increasingly performed in younger, more active patient populations.
• Long-term durability of TKRs is a significant concern, necessitating advancements in implant design and materials.
• Modular knee-replacement systems offer versatility but require robust wear performance.

Purpose of the Study:

• To evaluate the long-term wear performance and durability of mobile-bearing TKR designs.
• To compare the outcomes of mobile-bearing TKRs with fixed-bearing designs.
• To identify areas for improvement in future mobile-bearing TKR designs.

Main Methods:

• Review of clinical outcomes and wear data for mobile-bearing TKRs (e.g., Oxford, LCS) with a minimum 10-year follow-up.
• Comparison of wear, loosening, and osteolysis rates against established fixed-bearing arthroplasty results.
• Analysis of fluoroscopic evaluations to assess implant kinematics.

Main Results:

• Some mobile-bearing TKR designs demonstrate wear performance comparable to the best fixed-bearing designs after 10 years.
• Key metrics such as loosening and osteolysis are comparable between certain mobile-bearing and fixed-bearing designs.
• Challenges remain in optimizing bearing-surface conformity and improving kinematics.

Conclusions:

• Enhanced wear performance is essential for the long-term success of TKRs in active patients.
• Mobile-bearing TKRs can achieve comparable durability to fixed-bearing designs, but require further refinement.
• Future designs must focus on controlling bearing mobility to prevent abnormal kinematic motions and improve patient outcomes.