Purpose

Meniscus tears are one of the most common knee injuries, with damage to the avascular region having poor healing potential. Partial meniscectomy is commonly used to treat meniscal tears but often leads to osteoarthritis (OA). Meniscus replacement strategies aimed at alleviating joint stress and preventing OA, including allografts or synthetic implants, suffer from either limited tissue availability or poor surgical performance. Our goal is to generate a 3D bioprinted partial meniscus implant with mechanical properties sufficient for arthroscopic surgical fixation, immediate load-bearing, and long-term performance to restore knee joint health and prevent the development of OA.

Methods and Materials

Novel blends of chitosan and polyvinyl alcohol (PVA) were bioprinted using the microfluidic RX1™ Bioprinter (Aspect Biosystems Ltd.). A composite implant was fabricated consisting of a meniscus-sized bioprinted chitosan/PVA mesh combined with a cast PVA solution. Suture pull-out strength, tensile strength, and compressive strength were measured using a Mach-1 mechanical testing device. Cadaveric porcine knees are being used to demonstrate compatibility with standard arthroscopic surgical procedures.

Results

Bioprinted chitosan/PVA blends exhibited high suture retention strength, tensile strength, elasticity, and recovery after mechanical deformation. Combining the bioprinted mesh with the cast PVA matrix into a "composite" tissue had a synergistic effect on mechanical performance compared to bioprinted-only or cast-only implants (Figure 1). Partial composite meniscus implants are being shuttled into the knee joint and fixated to the intact host peripheral meniscus tissue of cadaveric porcine knees to illustrate the feasibility of this surgical approach ex vivo (Figure 2).

Figure 1.

Figure 2.

Conclusion

A novel chitosan/PVA implant for partial meniscus replacement was developed using a unique microfluidic bioprinting technology. This bioprinted meniscus implant exhibits mechanical properties appropriate for arthroscopic surgical fixation and short-term load-bearing ex vivo and will be confirmed in vivo using a large animal model to study biological and mechanical performance.