Implants for Small Bone Fractures
For shaft fractures of large hollow bones such as the humerus, femur and bones of the lower leg, intramedullar implants are used routinely with success. Such implants are inserted into the cavity in the bone during an operation for this purpose. Until now, however, an intramedullar implant with adequate stability was not available to treat shaft fractures of small hollow bones such as the collarbone (clavicle), metacarpal bones or ribs. At the same time, fractures of small hollow bones are the most common fractures in human and veterinary medicine.
For this reason, a new type of intramedullar implant for treatment of shaft fractures of small hollow bones is being developed in an interdisciplinary research project. The implant has a traction cable with an anchor at either end and runs through the medullary cavity. This traction cable neutralizes the telescoping axial forces and presses the end of the fracture together. As a result, the bone heals quickly and reliably. Additional splinting that surrounds the cable assembly and fills the intramedullary cavity prevents the ends of the fracture from separating.
Since the components of the implant are supposed to be made of resorbable polymers based on polylactic acid (PLA), it is not necessary to remove the implant surgically after the fracture has healed. Ii is further anticipated that, in the immediate area of the fracture, the implant will be coated with a polymer that contains bone growth-stimulating factors. These factors accelerate healing of the fracture, so that the patient can be free of pain sooner and the bone can support a load more quickly. A groove that runs around the circumference will be filled with the mixture of polymer and stimulating factors.
The project won the "Innovation Competition in Medical Technology for 2007" sponsored by the Federal Ministry for Education and Research (BMBF). Project partners include the surgical clinic of Ludwig Maximilian University (LMU) Munich, the Institute for Biomechanics and Experimental Orthopedics at LMU, the Institute for Plastics Processing at the RWTH Aachen (IKV), the Institute for Technical Macromolecular Chemistry at the RWTH Aachen as well as Merete Medical GmbH, Berlin, and Aesculap AG & Co. KG, Tuttlingen.