Surface contaminants, such as bacterial debris and manufacturing residues, may remain on orthopedic implants after sterilization procedures and affect osseointegration. The goals of this study were to develop a murine model of osseointegration in order to determine whether removing surface contaminants enhances osseointegration. To develop the murine model, titanium alloy implants were implanted into a unicortical pilot hole in the mid-diaphysis of the femur and osseointegration was measured over a five week time course. Histology, backscatter scanning electron microscopy and X-ray energy dispersive spectroscopy showed areas of bone in intimate physical contact with the implant, confirming osseointegration. Histomorphometric quantification of bone-to-implant contact and peri-implant bone and biomechanical pullout quantification of ultimate force, stiffness and work to failure increased significantly over time, also demonstrating successful osseointegration. We also found that a rigorous cleaning procedure significantly enhances bone-to-implant contact and biomechanical pullout measures by two-fold compared with implants that were autoclaved, as recommended by the manufacturer. The most likely interpretation of these results is that surface contaminants inhibit osseointegration. The results of this study justify the need for the development of better detection and removal techniques for contaminants on orthopedic implants and other medical devices.
Bibliographical noteFunding Information:
This work was supported by NIH T32 AR07505 (LAB), a pilot grant from the CCF/NIH Musculoskeletal Core Center Grant P30 AR-050953 (EMG and RWC), a Sulzer Medical Research Fund Grant (EMG and VMG), and the Harry E. Figgie III MD Professorship (EMG) . We would like to thank Reza Sharghi-Moshtahgin for assistance with backscatter scanning electron microscopy and X-ray energy dispersive spectroscopy; Radhika Patel and Antoine van den Bogert for their help with biomechanical testing; Teresa Pizzuto for histological preparation; and Amit Vasanji for μCT assistance.
- Biomechanical testing