In-vivo evaluation of the kinematic behavior of an artificial medial meniscus implant: A pilot study using open-MRI

• Pilot study to evaluate kinematics of a knee with an artificial meniscus device
• No in-vivo influence on femoral roll-back and tibiofemoral contact points
• No significant radial displacement or height loss of the implant during knee flexion
• We suggest that the knee maintains its static kinematic properties after implantation.
• Future research required in a larger population under dynamic conditions

BackgroundIn 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.MethodsThree 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.FindingsNo difference (P > 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 > 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.InterpretationIn 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.