In-vivo evaluation of the kinematic behavior of an artificial medial meniscus implant: A pilot study using open-MRI Tineke De Coninck a, ⁎, Jonathan J. Elsner b , Eran Linder-Ganz b , Michiel Cromheecke c , Maoz Shemesh b , Wouter Huysse a , René Verdonk c , Koenraad Verstraete a , Peter Verdonk c,d a Department of Radiology, Ghent University Hospital, De Pintelaan 185, B-9000 Ghent, Belgium b Active Implants Israel Ltd., R&D Department, 43 Hamelacha St., P.O. Box 8395, Netanya 42505, Israel c Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185, B-9000 Ghent, Belgium d Antwerp Orthopedic Center, Monica Hospitals, Harmoniestraat 68, 2018 Antwerp, Belgium abstract article info Article history: Received 22 December 2013 Accepted 9 July 2014 Keywords: Meniscus Open MRI Polycarbonate-urethane implant Kinematics Displacement Background: In this pilot study we wanted to evaluate the kinematics of a knee implanted with an artificial polycarbonate-urethane meniscus device, designed for medial meniscus replacement. The static kinematic behavior of the implant was compared to the natural medial meniscus of the non-operated knee. A second goal was to evaluate the motion pattern, the radial displacement and the deformation of the meniscal implant. Methods: Three patients with a polycarbonate-urethane implant were included in this prospective study. An open-MRI was used to track the location of the implant during static weight-bearing conditions, within a range of motion of 0° to 120° knee flexion. Knee kinematics were evaluated by measuring the tibiofemoral contact points and femoral roll-back. Meniscus measurements (both natural and artificial) included anterior– posterior meniscal movement, radial displacement, and meniscal height. Findings: No difference (P N 0.05) was demonstrated in femoral roll-back and tibiofemoral contact points during knee flexion between the implanted and the non-operated knees. Meniscal measurements showed no significant difference in radial displacement and meniscal height (P N 0.05) at all flexion angles, in both the implanted and non-operated knees. A significant difference (P ≤ 0.05) in anterior–posterior movement during flexion was observed between the two groups. Interpretation: In this pilot study, the artificial polycarbonate-urethane implant, indicated for medial meniscus replacement, had no influence on femoral roll-back and tibiofemoral contact points, thus suggesting that the joint maintains its static kinematic properties after implantation. Radial displacement and meniscal height were not different, but anterior–posterior movement was slightly different between the implant and the normal meniscus. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Meniscal lesions are one of the most frequently observed knee injuries, and due to increasing sport activities, their number is still increasing (Majewski et al., 2006). One of the most frequently performed treatment options is a partial meniscectomy (Abrams et al., 2013). The short-term clinical outcome is usually beneficial by resolving pain; however, articular cartilage degeneration and osteoarthritis are likely to develop in the long run (Petty and Lubowitz, 2011). If the removed meniscal tissue could be replaced by an artificial meniscus, it could have a positive effect in both the short- and long-term in relieving knee pain and restoring knee congruency. Therefore, new meniscal restoration strategies are developing rapidly to restore knee kinematics. The successful use of biological solutions, such as meniscal allografts and biodegradable scaffolds is usually limited to patients below 50 years of age. Thus, in order to fulfill the need for treatment of chronic, middle-aged patients with a dysfunctional and painful meniscus, a synthetic and functional free-floating polycarbonate-urethane (PCU) implant was developed for medial meniscal replacement (NUsurface®, Active Implants Corp., Memphis, TN, USA) (Elsner et al., 2010). The use of open field magnetic resonance imaging (MRI) to analyze human knee kinematics and meniscal movement in three dimensions is well documented in recent publications (Kaiser et al., 2013; Qi et al., 2013). Recent studies confirmed that a consistent pattern of lateral femoral roll-back exists in extension (Freeman and Pinskerova, 2005; Kozanek et al., 2009; Pinskerova et al., 2004). Also the natural meniscal Clinical Biomechanics xxx (2014) xxx–xxx ⁎ Corresponding author at: Department of Radiology, Ghent University Hospital, De Pintelaan 185, B-9000 Ghent, Belgium. E-mail addresses: tineke.deconinck@ugent.be (T. De Coninck), jon.elsner@activeimplants.com (J.J. Elsner), eran.ganz@activeimplants.com (E. Linder-Ganz), michiel.cromheecke@gmail.com (M. Cromheecke), maoz.shemesh@activeimplants.com (M. Shemesh), wouter.huysse@gmail.com (W. Huysse), Rene.Verdonk@uzgent.be (R. Verdonk), koenraad.verstraete@ugent.be (K. Verstraete), pverdonk@yahoo.com (P. Verdonk). JCLB-03819; No of Pages 8 http://dx.doi.org/10.1016/j.clinbiomech.2014.07.001 0268-0033/© 2014 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Clinical Biomechanics journal homepage: www.elsevier.com/locate/clinbiomech Please cite this article as: De Coninck, T., et al., In-vivo evaluation of the kinematic behavior of an artificial medial meniscus implant: A pilot study using open-MRI, Clin. Biomech. (2014), http://dx.doi.org/10.1016/j.clinbiomech.2014.07.001