(178f) Resorbable Bone Pins for the Reduction of Fractures

Orthopedic implants are fixation devices that are used to fix pieces of bone together and provide structural support. Traditional metallic Orthopedic implants have several shortcomings such as stress shielding, need for a revision surgery and growth restriction in young patients. This necessitates the need for resorbable Orthopedic implants. The use of a resorbable material to fabricate orthopedic implants eliminates the need for a second surgical procedure, prevents stress-shielding caused by metallic implants and thus increases patient comfort. A commonly used implant to aid the fixation and reduction of smaller bone fragments is a Bone Pin, which requires sufficient mechanical strength to hold the bone fragments, must be biocompatible, and have suitable grip. Current commercial resorbable bone pins are fabricated from PolyLactic acid, which suffers from inadequate osteoconductivity and often lose efficacy in the late stage of implantation because of the inflammatory response of acid by-products released upon degradation and inability integration to bone. Polycaprolactone is a bioresorbable polymer with excellent biocompatibility and non-toxic degradation by-products. (Suryavanshi et al,2017). The degradation characteristics and strength of Polycaprolactone can be tuned by the addition of hydrophilic fillers such as Magnesium Oxide (MgO) and commercial Degummed Silk Powder (SP). (Suryavanshi et al,2019).

We have fabricated composites of PCL (PCL/SP/MgO) with varying filler concentrations of MgO (0-20%) and SP (0-20%) by melt mixing at a temperature of 160 degrees and subsequent Injection Molding. The ASTM composites are tested for their mechanical strength and it is observed that the Youngs modulus of PCL/SP10/MgO10 is 1.8 times that of PCL and PCL/SP0/MgO20 is approximately 2.2 times that of PCL. The in-vitro cellular viability of composites was determined using a cytotoxicity (MTT) assay with Osteosarcoma (SaOS-2) cells. PCL/SP10/MgO10 composites demonstrated the highest cell viability. Thus, we may infer that, composite and its fabrication process (injection molding) did not have any harmful effect on the viability of Osteosarcoma indicating good cellular biocompatibility in vitro. Further studies include fabrication of the bone pin prototype by injection molding in a suitable mold, in vitro degradation, testing the bending strength of these pins, and subsequent implantation in a suitable in vivo model.

References:

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