A Long-term Simulated Degradation Study of a Synthetic Meniscus Implant: Material and Functional Properties

The NUsurface^® is a synthetic non-anchored polycarbonate-urethane meniscus implant, reinforced with polyethylene fibers. This study aimed to evaluate the long-term performance and potential degradation of the device by subjecting it to a full mixed-mode gait-like loading regime for 5 million cycles (Mc). Five implants undergo full mixed-mode and additional one served as load-soak control (vertical force only). The simulation had stops at 0.5, 1, 1.5, 2, 3, 4 and 5 Mc at which each implant was weighed and its load distribution was recorded. After completion, the implants were analyzed by ESEM, AFM, GPC and FT-IR in order to evaluate the effect of biodegradation. ESEM images demonstrated only minor damage on the superior articulating surface, very little change was documented in the chemical footprints (less than 6% increase in oxidation) and the ability to distribute load improved over time with a contact area of 1.4 of the baseline area. The implant was found to be resilient enough to maintain its form and material properties throughout the simulation with low wear rate.