Comparing Patient Preference for Highly-Congruent versus Cruciate-Retaining Inserts in Bilateral Knee Arthroplasties

The purpose of this study was to determine if patients who had undergone bilateral total knee arthroplasty (TKA) with a cruciate-retaining (CR) bearing in one knee and a highly-congruent bearing in the other had a preference between the two bearings.

We retrospectively identified 104 patients who had bilateral TKAs performed an average of 15 months apart (range, simultaneous to 11 years apart) by one surgeon using one implant system, with each patient having a CR bearing in one knee and a highly-congruent in the other. Mean age at surgery was 62 years (range, 43 to 88), and 62% were women. We assessed implant survival, reoperation rate, and range of motion. Patient knee preference, satisfaction, subjective instability, and other patient-reported outcome measures were also analyzed. A power analysis revealed that 81 knees in each group were required to detect a difference in laterality preference of 20% (alpha = 0.05, beta = 0.80). Univariate analyses with alpha < 0.05 were used in comparisons between groups.

At a mean of 5.4 years, 27 patients (26%) preferred their CR knee, 25 patients (24%) preferred their highly-congruent knee, and 52 patients (50%) had no preference (P = 0.9). There were 35 patients (34%) who preferred the first knee that was operated on versus 14% who preferred the second (P < 0.001). There was no difference in prosthesis survival (P = 0.4) or reoperations (P = 0.1) between groups. Additionally, there was no difference in patient satisfaction, knee flexion, or patient-reported outcome measures.

Patients who had a CR insert in one knee and a highly-congruent insert in the other did not prefer one versus the other. There was no difference in survival, outcomes, or postoperative range of motion between the two bearings, demonstrating both as reliable and adequate choices in TKA.