A Functional Analysis of a Resorbable Citrate-based Composite Tendon Anchor
Orthopaedic fixation seeks solutions to the challenges of non-union, reconstructive surgery, and soft tissue injuries by providing stability and tissue alignment during the healing process. Risks associated with fixation devices such as peri-implant resorption, implant loosening and sub-optimal device resorption remain a significant challenge in the development of transient fixation devices. Osteomimetic biomaterials, and in particular, bio-resorbable polymer composites designed to match the mineral phase content of native bone have been shown to exhibit osteoinductive and osteoconductive properties in vivo and have been used in bone fixation for the past 2 decades. However, the specific signalling pathways driving the osteogenic response to these biomaterials remain largely unknown. In this study a resorbable, bioactive, and mechanically robust citrate-based composite, formulated from poly(octamethylene citrate) (POC) and hydroxyapatite (HA) (POC-HA) was investigated as a potential orthopedic biomaterial. In vitro analysis with human Mesenchymal Stem Cells (hMSCs) indicated that POC-HA composite materials supported cell adhesion, growth, and proliferation and increased calcium deposition, alkaline phosphatase production, the expression of osteogenic specific genes and activation of canonical pathways leading to osteoinduction and osteoconduction. Further in vivo evaluation of a POC-HA tendon fixation device in a sheep metaphyseal model indicated the regenerative and remodelling potential of this citrate-based composite material in orthopedic applications.