Ultra-Congruent Versus Cruciate-Retaining Inserts in Bilateral Simultaneous Total Knee Arthroplasty: A Prospective...

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Prosthetic design

Background:

• Total knee arthroplasty (TKA) prosthetic design aims to replicate native knee function.
• Conflicting evidence exists on the efficacy of different TKA insert designs (e.g., ultra-congruent vs. cruciate-retaining) based on patient-reported and objective outcomes.
• Understanding patient satisfaction differences between TKA insert designs is crucial for optimizing surgical outcomes.

Purpose of the Study:

• To compare patient satisfaction between ultra-congruent (UC) and cruciate-retaining (CR) insert designs in bilateral simultaneous TKA.
• To investigate objective parameters that may explain any observed differences in outcomes between UC and CR TKA inserts.

Main Methods:

• A prospective, randomized, double-blinded, Level I trial involving 53 patients undergoing bilateral simultaneous TKA.
• Patients received randomly assigned UC inserts in one knee and CR inserts in the contralateral knee.
• Primary outcome: Forgotten Joint Score (FJS); Secondary outcomes: Oxford Knee Score (OKS), Knee Society Score (KSS), gait analysis, and stability assessments at multiple postoperative intervals (3, 12, 24 months).

Main Results:

• The UC insert group demonstrated significantly superior Forgotten Joint Scores (FJS) at all postoperative time points compared to the CR insert group (P < 0.05).
• The largest difference in FJS was observed at the one-year follow-up (UC: 73.2 ± 6.0 vs. CR: 67.5 ± 16.6; P = 0.007).
• No statistically significant differences were found between the UC and CR groups for other assessed clinical, radiological, or gait parameters.

Conclusions:

• Ultra-congruent (UC) inserts provide significantly better patient-reported joint awareness (FJS) compared to cruciate-retaining (CR) inserts up to 2 years post-TKA.
• The enhanced subjective patient outcomes with UC inserts were not corroborated by objective clinical or biomechanical measures.
• UC inserts represent a viable alternative to CR inserts in PCL-sacrificing TKA, offering improved patient-perceived joint function.