To further its custom compounding operation, PolyMedex (Putnam, CT) has invested in a Leistritz twin-screw extruder to allow for small-scale development batches that are scalable to full production. The smallest batch size ordered can be less than one kilogram, PolyMedex said in answer to a question from MPW.
The company blends bioactive fillers such as tricalcium phsphate (TCP), hydroxyapatite (HA), and biphasic calciumphosphate (BCP) to make them osteoconductive, meaning that bone will grow on and bond to the plastic. Implantable plastics such as polyetheretherketone (PEEK) are used in permanent implants; bioresorbable polymers such as polycaprolactone (PCL), polylactic acid (PLA) and polyglycolide (PGA) are used in implants for temporary support while the body heals and ultimately replaces the implant with bone. PolyMedex customizes bioresorbable polymers for resorption ranges from 1 to 36 months and flexural modulus from 30,000 psi (200 MPa) to more than 1,000,000 psi (6900 MPa).
The implantable polymers are available in multiple delivery forms. Implant components can be precision cut from extruded film and fiber, or implant designs are possible with implantable polymers in the form of coextruded and multi-lumen tubing. For injection molding, PolyMedex's custom formulations are available in a variety of pellet sizes for processing in standard or micromolding equipment.