Compound meniscus implant prototypes : Bench test performance of knitted casing to contain, fixate and mechanically stabilize cell seeded gels

Abstract: Meniscal tears are the most common intra-articular injury of the knee joint. Due to the avascular zone with limited blood supply, treatment of the injury is a complex process. Today, research on the development of efficient treatments and meniscal replacements is of increasing interest. However, there are few alternatives of meniscal replacements available on the market and research has shown uncertain results in their ability to restore the natural biomechanics of the knee joint or prevent development of osteoarthritis. Furthermore there is no comparable method to evaluate tensile stresses caused by axial compressional load on a whole meniscus replacement. Therefore the possibility of knitted casing to contain, fixate and mechanically stabilize a cell seeded bioprinted gel and develop a methodology to characterize its compressional behaviour was analysed. By interlock knitting with segments of partial knit a 3D crescent-shaped biodegradable casing was produced mimicking the dimension of the medial meniscus. In the casing design, an Artelon® Flexband™ was incorporated functioning both as reinforcement at the peripheral rim and as fixation method. Moreover radial threads were added to the casing design by inclusion of weft inlays in the knitting pattern. In the non-destructive characterization of the compressional behaviour of the prototype, axial compressional forces of 10.82 N and 29.77 N were achieved. However the forces achieved were significantly lower if compared to the high force that is applied to the menisci in the knee joint. Furthermore a high influence of the coefficient of friction of the casing in the axial compressional force was concluded. Nevertheless refinements of the methodology are required to perform evaluation with comparable and reliable results.