Development of Expandable Implant with Structural Support to the Bone Tissue

Bone defects caused by osteonecrosis, bone tumor resection, or osteoporotic fracture are often treated by bone grafting procedure. No matter autogenic, allogenic, or synthetic grafts, the processes of creeping substitution and remodeling are essential for the healing of the bone defects. It is, however, mechanically undesirable during the remodeling stage that the grafts will lose their supporting strength gradually. Without adequate mechanical support, the bone defects might be collapsed or deformed and could not sustain the physical loading in the daily activity. The purpose of this proposal is to develop a kind of expandable implants that can provide adequate mechanical strength to the bone defects without interfering with the remodeling of the grafts. Minimally invasive procedure combined with bio-products, stem cells, or regenerative medical therapy is taken as the future directions for many orthopaedic disorders. The expandable titanic implants are aimed to amend the current treatment modalities and provide the possibilities for combination therapies in treating bone defects. The project is to develop the expandable titanic implants and their surgical tools. The products can be used in osteonecrosis of the femoral head, bone tumor resection, and osteoporotic vertebral compression fracture. The innovation of the design is a mechanically driven implant with multi-layer dome-shaped structures or bullet-type expandable cage. A smart-linked mechanism manipulated from the bottom of the implant can control its expansion or contraction. The expandable implant that increases the contact area in the bone defect can reduce the stress riser and stress concentration within the void. In the first year, this project aims at the surgical tools and implants development. Biomechanical testing for the implants will be used for further refinement of our designs. In the second year, biocompatibility including local tissue reaction, systemic inflammatory reactions, metal ions release, and renal function tests will be stressed in accordance to the biomechanical tests to validate the feasibility of the implants. In the third year, non-invasive image analyses, histology studies, and mechanical push-out tests will be carried to investigate the osteointegration of the implants. It is hoped that this project can generate medical device patents and foster technology transfer for domestic medical device industry. By cultivating promising talents in the biomechanical field through the implementation of this project and the attendance of invention contests, we hope that the innovative expandable implants can attract attention from the biotech industry to facilitate preclinical trials and clinical use in the future.

Project ID:PC9910-0028
External Project ID:NSC99-2321-B182-006