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

The prosthetic design landscape for total knee arthroplasty (TKA) is extensive. Modified surface geometries aim to replicate native kinematics for superior outcomes, yet evidence remains conflicting regarding optimal design efficacy based on patient-reported and objective metrics. The primary aim of this study was to compare the patient satisfaction between ultra-congruent (UC) and cruciate-retaining (CU) insert designs in bilateral simultaneous TKA, and the secondary aim was to study the parameters validating potential reasons behind any differences in the outcomes between these two design philosophies.

In this institutional review board-approved, prospective, randomized, double-blinded (patient/assessor), level I trial, there were 53 patients (mean age 63 years [range, 54.8 to 66.6] and 45 women). Patients who had bilateral end-stage osteoarthritis underwent bilateral simultaneous TKA by a single surgeon. Each patient received a randomly assigned UC insert in one knee and the contralateral knee received a CR insert. The primary outcome was the Forgotten Joint Score (FJS). The secondary outcomes included clinical and radiological parameters, including Oxford Knee Score, Knee Society Score, and gait analysis. Patients were assessed preoperatively and at three, 12, and 24 months postoperatively. Intraoperative static stability and postoperative (six months) dynamic stability was assessed.

The UC group demonstrated significantly superior FJS at all postoperative intervals (P < 0.05), with the largest difference at 1 year (UC: 73.2 ± 6.0 versus CR: 67.5 ± 16.6; P = 0.007). There were no statistically significant differences found in other parameters at any time point between the two groups.

The UC inserts provide significantly better patient-reported joint awareness (FJS) compared to CR inserts at 2-year follow-up in bilateral simultaneous TKA. This subjective advantage was not validated by differences in objective parameters. The UC design represents a viable posterior cruciate ligament-sacrificing alternative with enhanced patient-perceived outcomes.

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