Article
Histological analysis of bone regeneration with different doses of rhBMP-2 in a large animallumbar interbody fusion model
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Authors
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Christian Hohaus
- Städtisches Klinikum Dessau, Klinik für Neurochirurgie, Dessau, Deutschland; BG Klinikum Bergmannstrost, Klinik für Neurochirurgie, Halle, Deutschland
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Johannes Seeger
- Universität Leipzig, Veterinärmedizinische Fakultät, Leipzig, Deutschland
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Katharina Siegrist
- Universität Leipzig, Veterinärmedizinische Fakultät, Leipzig, Deutschland
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Hans Jörg Meisel
- BG Klinikum Bergmannstrost, Klinik für Neurochirurgie, Halle, Deutschland
| Published: | June 18, 2018 |
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Outline
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Objective: The objective of this study was to investigate the effects of different doses rhBMP-2 on bone healing in an ovine lumbar interbody fusion model.The use of rhBMP-2 becamevery common in lumbar interbody fusion techniques in the first decade of the century after very promising studies in the late 1990s.
Methods: In this study 22 sheep underwent two level lumbar interbody fusion using a ventrolateral approach with secondary dorsal fixation at L1/2 and L3/4. After randomization in one level a PEEK-cage was implanted filled with one of three doses rhBMP-2 (0,5mg; 1mg; 2mg) delivered on an ACS. The other level received an empty PEEK-cage or ACS filled cage. Animals were sacrificed after 3 and 6 months and decalcified histology was performed. This included histomorphological analysis as well as histomorphometry of the tissues within the cage.
Results: 3 months after surgery the groups treated with rhBMP-2 showed higher amounts of bone tissue within the cage. At 6 months the amounts of bone tissue increased in all groups, but were still lower in the groups without growth factor.
At 3 months there was only one active osteolysis in the cage/ACS. 7 of 8 segments of the rhBMP-2 groups had a compromised bone structure filled with fibrous tissue and fibrocartilage. This finding was not detected in the groups without rhBMP-2 at 3 months.
At 6 months most of the segments with an empty cage or cage/ACS showed a chronic inflammation. Predominant cells were macrophages and giant cells. The groups treated with rhBMP-2 showed only a few mild chronic inflammatory reactions.
Conclusion: As known we also recognized a better fusion result with higher concentrations of BMP2. We could evaluate that less side effects were seen in the lowest BMP 2 group.
Attention has to be payed for the proinflammatory properties of the growth factor. Osteoblasts, but not osteoclasts, were seen in the periphery of the resorption areas within the BMP2 filled cages after 3 months. This finding wasn’t recognized at 6 months anymore.
Striking is that at 6 months most of the segments without rhBMP-2 showed a compromised bone structure around the implant with a mild to mainly moderate chronic inflammatory reaction. The ACS must be considered as reason therefore.
