The combination of tibial anterior translation and axial rotation into a single biomechanical factor improves the prediction of patient satisfaction over each factor alone in patients with ACL reconstructed knees

• Type of Material: Article
• Authors: Thomas P. Branch, University Orthopedics; Shaun K. Stinton, ArthroMetrix LLC; William Hutton, Emory University; Philippe Neyret, Hopital de la Croix-Rousse
• Language: English
• Date: 2017-04-01
• Publisher: Springer Verlag (Germany)
• Publication Version: Final Published Version
• Copyright Statement: © 2017, The Author(s).
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1007/s00167-017-4497-7
• Title of Journal or Parent Work: Knee Surgery, Sports Traumatology, Arthroscopy
• ISSN: 0942-2056
• Volume: 25
• Issue: 4
• Start Page: 1038
• End Page: 1047
• Grant/Funding Information: This paper was supported by the following grant(s): ERMI, Inc.
• Keywords: ACL; Anterior knee laxity; Joint play envelope; Patient satisfaction; Knee laxity; ACL reconstruction; Rotational knee laxity
• Research Categories: Health Sciences, Public Health; Health Sciences, Medicine and Surgery

Abstract

Purpose: The purpose of this study was to identify biomechanical factors, in both reconstructed and healthy knees, that correlate with patient satisfaction after ACL reconstruction. Methods: Seventeen patients who had undergone unilateral ACL reconstruction were reviewed 9 years post-op. Patients completed subjective questionnaires and underwent manual knee laxity testing (Lachman-Trillat, KT-1000, and pivot shift) and automated laxity testing. During automated testing, both legs were rotated into external rotation and then internal rotation until peak rotational torque reached 5.65 Nm. Load-deformation curves were generated from torque and rotation data. Features of the curves were extracted for analysis. Total leg rotation and anterior laxity during KT-1000 testing were combined into a single factor (Joint Play Envelope or JPE). Patients were divided into groups based on patient satisfaction scores (Group 1: Higher Satisfaction, Group 2: Lower Satisfaction, Group 3: Unsatisfied). Load-deformation curve features and manual laxity testing results were compared between groups 1 and 2 to determine which biomechanical factors could distinguish between the groups. Diagnostic screening values were calculated for KT-1000 testing, the pivot shift test, total leg rotation and JPE. Results: During manual testing, no significant differences in biomechanical factors were found when comparing reconstructed knees in group 1 and group 2. When comparing the reconstructed and healthy knees within group 2, the reconstructed knees had a significantly higher displacement during the KT-1000 manual maximum test (p < 0.002). When considering the reconstructed knees alone, neither the result of the pivot shift test nor KT-1000 testing could distinguish between group 1 and group 2. During automated testing, there were no significant differences between the groups when comparing the reconstructed lower limbs. The healthy lower limbs in group 2 had more maximum external rotation (p < 0.02) and decreased stiffness at maximum external rotation (p < 0.02) when compared to the healthy lower limbs in group 1. Total leg rotation was unable to distinguish between group 1 and group 2. JPE could distinguish between group 1 and group 2 when considering the reconstructed limb alone (p < 0.02). All four diagnostic screening values for JPE were equal or higher than in the other criteria. JPE also showed the most significant correlation with patient satisfaction. Conclusions: Joint Play Envelope is an objective measure that demonstrated improved predictive value as compared to other tests when used as a measure of satisfaction in patients with ACL reconstructed knees.