Injectable biodegradable elastomer to aid in healing of bone fractures

Statement of Purpose: In the United States every year, there are over 500,000 fractures of the lower extremities.¹ With current treatments, 10%-20% of fractures fall into delayed or nonunion categories.² For successful bone healing, a key challenge is sufficient mechanical stability of the injury, as well as eventual biodegradability of the mechanical support to reduce stress shielding.^1,2 As such, a market has developed for biodegradable materials that can enhance bone healing to aid in short term stabilization and long-term recovery. A commercial product approved by the FDA to aid in bone defects and certain skeletal fractures is calcium phosphate cement CPC.³ However, CPC is limited in its clinical use for bone fractures due to its weak mechanical properties of brittleness, low impact resistance, and low tensile strength.³ A bone cement that may address these issues is a biodegradable elastomer called POC poly1,8-ocatanediol-co-citratre, which was developed in the Ameer lab and has different clinical applications due to its biodegradability, tissue biocompatibility, and mechanical strength.⁴ Specifically, a composite consisting of POC and bioceramic hydroxyapatite HA has shown to have desirable biodegradable properties and mechanical characteristics similar to the range of values reported for tissue fixation devices.⁵ Bending, compression, tensile, and sheer strength were measured, but the fractural strength provided by this POC-HA composite remains untested.⁵ This study proposes an experiment to test the fractural strength provided by different POC-HA composites using a 3-point flexural bending test, with the goal of finding the ideal HA composite for desired mechanical characteristics.