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Bone apposition to plasma-sprayed cobalt-chromium alloy.
H A Luckey1, E G Lamprecht, M J Walt
1Orthopedic Products Division/3M, 3M Center, St. Paul, Minnesota 55144.
Journal of Biomedical Materials Research
|May 1, 1992
Summary
This study compared porous and plasma-sprayed metallic coatings for joint prostheses fixation. Plasma coatings showed potential advantages in cancellous bone sites, offering improved biological fixation over time.
Area of Science:
- Biomaterials Engineering
- Orthopedic Surgery
- Tissue Engineering
Background:
- Porous metallic coatings are used for bone ingrowth fixation of joint prostheses, offering an alternative to bone cement.
- Concerns include metal ion release, coating delamination, and reduced fatigue strength of porous coatings.
- Nonporous, high-integrity plasma-sprayed cobalt-chromium (CoCr) coatings present an alternative with potentially different biological fixation characteristics.
Purpose of the Study:
- To compare the biological fixation of a nonporous plasma-sprayed CoCr coating versus a conventional sintered bead porous coating.
- To evaluate fixation quality in both cortical and cancellous bone sites at 8 and 16 weeks post-implantation.
- To assess shear strength at the bone/implant interface for both coating types.
Main Methods:
- Goat models were used with implants featuring either porous sintered bead or nonporous plasma-sprayed CoCr coatings.
- Implants were placed in cortical and cancellous bone sites.
- Histological evaluation and shear testing were performed at 8 and 16 weeks to assess bone ingrowth and interface strength.
Main Results:
- Histological evaluation revealed significant inter-animal and inter-site variability, with no consistent differences between implant types.
- Shear testing showed higher average strengths for porous coatings in cortical bone, but not statistically significant.
- In cancellous bone, average shear strengths were similar, but paired analysis indicated plasma coatings yielded higher strengths at 16 weeks.
Conclusions:
- While overall differences were not significant, plasma-sprayed CoCr coatings demonstrated consistent higher shear strength in cancellous bone at later time points when directly compared to porous coatings.
- The nonporous plasma-sprayed surface may offer advantages for biological fixation, particularly in metaphyseal bone regions.
- Further investigation into plasma-sprayed coatings is warranted for total joint prosthesis applications.