Lateral-Conforming Dual-Pivot Versus Nonconforming Anterior-Stabilized Bearings in Valgus Knees Undergoing Primary Total Knee Arthroplasty.

BACKGROUND

Personalized alignment strategies in total knee arthroplasty (TKA) have gained in popularity to recreate native biomechanics and improve outcomes. Prior studies have reported better patient-reported outcome measures (PROMs) for preoperative valgus deformities (compared to varus) when medial-conforming bearings are used. This study evaluated PROMs in a lateral-conforming dual-pivot (DP) bearing compared to a nonconforming anterior-stabilized (AS) bearing after primary TKA.

METHODS

A retrospective review was performed on 2,427 primary TKAs implanted with either a DP conforming bearing or a nonconforming AS bearing. The coronal limb alignment was measured on short-leg radiographs, which identified 291 DP and 77 AS TKAs as valgus preoperatively (representing 15.9% of the series). Modern PROMs and clinically relevant thresholds were evaluated at a significance level of 0.05, accounting for multiplicity.

RESULTS

In multivariable analyses, the AS group had a significant main effect on a greater likelihood of achievement for the Knee Society Score pain with climbing stairs minimal clinically important difference threshold (odds ratio 4.4, 95% confidence interval, 1.03 to 19.2) and the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement patient-acceptable symptom state threshold (odds ratio 2.4, 95% confidence interval, 1.1 to 5.0). While not statistically significant, the AS group reported higher satisfaction (87.7 versus 78.8%, unadjusted P = 0.068, Holm-P = 0.408) and that their knees felt "always" normal more often compared to the DP group (53 versus 44%, unadjusted P = 0.163, Holm-P = 0.815), which may represent a clinically meaningful difference.

CONCLUSIONS

In this single surgeon series, valgus knees using a DP lateral-conforming bearing were less likely to achieve clinically relevant PROMs thresholds compared to valgus knees using a traditional nonconforming bearing. Study results support the recent data suggesting valgus knees may achieve higher overall knee health postoperatively with medial-pivot bearing designs that enhance medial compartment stability.

LEVEL OF EVIDENCE: III.