Patient Specific Transdermal Osseointegrated Prosthetics:
A relatively new form of prosthetic attachment involves the use of a transcutaneous osseointegrated implant. This is a bone anchored implant that breaches the skin barrier at the amputation site with an abutment that facilitates the attachment of prosthetic limbs directly to the skeletal system. For situations requiring load bearing prosthetic lower limbs, these osseointegrated implants have addressed many of the problems associated with traditional (socket type) prosthetics. Bone anchored implants have been shown to increase the mobility and functionality of prosthetic limbs, as well as to improve the quality of life of amputees. However, poor healing at the skin/implant interface and the constant presence of bacterial infection associated with breaching the skin have been barriers to the practical implementation of this technology. The management of these infections after surgical implantation has typically involved the long-term administration of antibiotics delivered to the infection site via hematogenous routes.
To achieve the porous surfaces and geometries for sealing the skin implant interface, a relatively new form of additive manufacturing called electron beam melting will be used. This process is capable of producing extremely complex geometries in biocompatible metals directly from a 3D computer models using a focused electron beam to selectively melt layers of titanium powder to build an implant customized for a given individual. The same process facilitates the generation of engineered lattice structures which can be optimized for the specific requirements of the implant such as skin ingrowth. Through our work with the NCSU college of veterinary medicine, transcutaneous, osseointegrated implants have been designed and fabricated using electron beam melting, and successfully implanted into several dogs and cats . While the focus of this previous research has been to investigate the osseointegration of custom implants, the results and the unique capabilities of electron beam melting have lead to a new design for the geometry of the skin implant interface. There are several videos that describe this research in more detail.