Do Medial Pivot Kinematics Correlate With Patient-Reported Outcomes After Total Knee Arthroplasty?

Background: Many total knee arthroplasty (TKA) implants are designed to facilitate a medial pivot kinematic pattern. The purpose of this study was to determine whether intraoperative medial pivot kinematic patterns are associated with improved patient outcomes. Methods: A retrospective review of consecutive primary TKAs was performed. Sensor-embedded tibial trials determined kinematic patterns intraoperatively. The center of rotation (COR) was identified from 0 degrees to 90 degrees and from 0 degrees to terminal flexion, and designated medial-pivot or non-medial pivot based on accepted criteria. Patient-reported outcomes were measured preoperatively and at minimum one-year follow-up. Results: The analysis cohort consisted of 141 TKAs. Mean age and median BMI were 63.7 years and 33.8 kg/m(2), respectively. Forty-percent of TKAs demonstrated a medial pivot kinematic pattern intraoperatively. A medial pivot pattern was more common with posterior cruciate-retaining (CR) and posterior cruciate-substituting/anterior lipped (CS) implants when compared to posterior stabilized (PS) TKAs (P <=.0150). Regardless of bearing type, minimum one-year Knee Society scores and UCLA activity level did not significantly differ based on medial vs non-medial pivot patterns (P >=.292). For patients with posterior cruciate-sacrificing implants, there were trends for greater median improvement in Knee Society objective (46 vs 31.5 points, P=.057) and satisfaction (23 vs 14 points, P=.067) scores in medial pivot knees. Conclusion: A medial pivot pattern may not significantly govern clinical success after TKA based on intraoperative kinematics and modern outcome measures. Further research is warranted to determine if a particular kinematic pattern promotes optimal clinical outcomes. (C) 2017 Elsevier Inc. All rights reserved.