Current Tecnologies
Although other metals are utilized, the current gold standard for bone fixation hardware is titanium. Not only is it expensive to manufacture and therefore purchase, but implanting titanium in the body comes with certain risks capable of affecting the patient long after the healing process has been completed.
Once a titanium screw has been implanted into a bone, the material becomes a composite structure susceptible to “stress shielding”. Due to the difference in stiffness between titanium and cortical bone (≈105 GPa versus ≈19 GPa respectively), the implant is forced to bear the majority of the stress. Unfortunately, the piezoelectric nature of osteogenesis requires the bone to bear cyclic stresses, a process that is severely diminished by sharing the load with titanium. The consequential weakening of the bone surrounding the implant results in delamination of the implant requiring further surgery and discomfort.
Use of titanium implants in children/young adults is especially problematic; non-yielding metal implants installed in or around growth plates can inhibit bone lengthening. For this reason, metal screws and plates are usually removed from younger patients. Titanium is actually known to osteointegrate too well; hardware removal has the potential to traumatize the surrounding bone substrate. At the very least, this requires a second surgery, which means a second exposure to infection, anesthesia, complications, and recovery.
Approximately 4% of all patients with metal implants are innately allergic or will become allergic to the metal in their body. This process is exacerbated by micro particles of metal released into the body by wear. The subsequent inflammation and allergic reaction can result in further surgery.
Orthopedic surgeons often require small bones (or bone fragments) to rebuild severely damaged structures following a traumatic event. Plastic surgeons have similar needs, either repairing a damaged body or altering an undesirable morphology. Even oncological surgeons require fragments to replace pieces excised during bone tumor removal. Currently, the cutting edge of bone replacement is done using polymers such as HDPE (High-density Polyethylene) and PEEK (Poly ether ether ketone). Both thermoplastics are non-reactive within the body, therefore they persist, never truly allowing the body to be whole again.
From a pure material science perspective, any instance where there is a discontinuity in a material, there exists a region or point of stress concentration. Thus, there have been many documented cases of “stress-riser” fractures, whereby existing implants serve as initiation points for subsequent fractures.
Once a titanium screw has been implanted into a bone, the material becomes a composite structure susceptible to “stress shielding”. Due to the difference in stiffness between titanium and cortical bone (≈105 GPa versus ≈19 GPa respectively), the implant is forced to bear the majority of the stress. Unfortunately, the piezoelectric nature of osteogenesis requires the bone to bear cyclic stresses, a process that is severely diminished by sharing the load with titanium. The consequential weakening of the bone surrounding the implant results in delamination of the implant requiring further surgery and discomfort.
Use of titanium implants in children/young adults is especially problematic; non-yielding metal implants installed in or around growth plates can inhibit bone lengthening. For this reason, metal screws and plates are usually removed from younger patients. Titanium is actually known to osteointegrate too well; hardware removal has the potential to traumatize the surrounding bone substrate. At the very least, this requires a second surgery, which means a second exposure to infection, anesthesia, complications, and recovery.
Approximately 4% of all patients with metal implants are innately allergic or will become allergic to the metal in their body. This process is exacerbated by micro particles of metal released into the body by wear. The subsequent inflammation and allergic reaction can result in further surgery.
Orthopedic surgeons often require small bones (or bone fragments) to rebuild severely damaged structures following a traumatic event. Plastic surgeons have similar needs, either repairing a damaged body or altering an undesirable morphology. Even oncological surgeons require fragments to replace pieces excised during bone tumor removal. Currently, the cutting edge of bone replacement is done using polymers such as HDPE (High-density Polyethylene) and PEEK (Poly ether ether ketone). Both thermoplastics are non-reactive within the body, therefore they persist, never truly allowing the body to be whole again.
From a pure material science perspective, any instance where there is a discontinuity in a material, there exists a region or point of stress concentration. Thus, there have been many documented cases of “stress-riser” fractures, whereby existing implants serve as initiation points for subsequent fractures.
Bone Materials and Additive Manufacturing
Our mission is to create bone fixture parts from hydroxyapatite and a bioresorptive polymer, materials that are both bio-compatible. Hydroxyapatite is a ceramic material that makes up 50% of human bone by volume and 70% by weight. It is the main component of our product. The secondary product is a bioresorptive polymer, comprising between 8 to 13% of the final product. The addition of this bioresorptive polymer enhances the flexural strength of the composite. All of our products will be produced through additive manufacturing, wherein the hydroxyapatite slurry will be extruded to specific dimensions by our customized 3-D print head while being fed by an external pump.