Bioabsorbable polymeric fracture fixation devices aim to reduce stress shielding in bone

Approximately 55,500 proximal humeral fractures require surgical fixation annually. The current standard for internal humeral fracture fixation involves implantation of metallic rigid fixation devices to prevent dislocation of bone fragments. However, rigid fixation devices have high stiffness characteristics which can cause stress shielding of bone. A second method of fixation, called biological fixation, reduces stress shielding by reducing stiffness with more flexible devices. However, this approach leads to increased incidences of delayed healing and nonunion of fracture fragments. The purpose of our design is to create a device that implements two bioabsorbable polymers that degrade at different rates in an attempt to provide rigid fixation during the initial fracture healing phase, followed by a period of biological fixation, allowing for functional healing and reduction of stress shielding over time. The bioabsorbable property of the design permits the device to remain in situ, thus eliminating the need for removal surgery and risk of surgical site infection. The design has been demonstrated to exhibit varying axial, torsional, and flexural stiffness over time. By combining the benefits of current devices, the proposed design provides an improved solution for proximal humeral fracture fixation.