TY - JOUR T1 - Measuring Tibial Forces is More Useful than Varus-Valgus Laxities for Identifying and Correcting Overstuffing in Kinematically Aligned Total Knee Arthroplasty JF - medRxiv DO - 10.1101/19013755 SP - 19013755 AU - Roth, Joshua D. AU - Howell, Stephen M. AU - Hull, Maury L. Y1 - 2019/01/01 UR - http://medrxiv.org/content/early/2019/12/05/19013755.abstract N2 - Identifying and correcting varus-valgus (V-V) malalignment of the tibial component is important when balancing a kinematically aligned total knee arthroplasty (TKA). Accordingly, the primary objective was to determine whether the tibial forces or V-V laxities are more sensitive to, and thus more useful for identifying and correcting, V-V malalignments of the tibial component that overstuff a compartment. Calipered kinematically aligned TKA was performed on nine human cadaveric knees. Medial and lateral tibial forces and V-V laxities were measured from 0° to 120° flexion with an unmodified reference tibial component and modified tibial components that introduced ±1° and ±2° V-V malalignments from the reference component to overstuff either the medial or lateral compartment. Changes in the tibial forces were most sensitive to V-V malalignments at 0° flexion (medial = 118±34 N/deg valgus malalignment and lateral = 79±20 N/deg varus malalignment). The varus and valgus laxities were most sensitive to V-V malalignments at 30° flexion (−0.6±0.1 deg/deg varus malalignment) and 120° flexion (−0.4±0.2 deg/deg valgus malalignment), respectively. The maximum average signal-to-noise ratios of the sensitivities to changes in tibial forces and V-V laxities were 8.4 deg-1 and 0.9 deg-1, respectively, based on reported measurement errors (i.e., noise) using current intraoperative technologies (14 N and 0.7°). Because of the greater signal-to-noise ratios, measuring tibial forces is more useful than V-V laxities for identifying and correcting V-V malalignments of the tibial component that overstuff a compartment.Clinical Significance The sensitivities of tibial forces provide objective guidance to surgeons performing V-V recuts of the tibia.Competing Interest StatementOne author, MLH, received research funding from Zimmer Biomet for this study and receives research support from Medacta that is not related to this study. One author, SMH, receives IP royalties from and is a paid consultant and presenter/speaker for Biomet Sports Medicine and Medacta, and receives research support from Medacta, which are all unrelated to this study.Funding StatementThe authors acknowledge the support of the National Science Foundation (Award No. CBET-067527) and Zimmer Biomet (Award No. CW88095).Author DeclarationsAll relevant ethical guidelines have been followed; any necessary IRB and/or ethics committee approvals have been obtained and details of the IRB/oversight body are included in the manuscript.YesAll necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesPlease contact the corresponding author with requests for data. ER -