Artikel
Adjustable polyurethane foam as filling material for a novel spondyloplasty: biomechanics and biocompatibility
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Autoren
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Kerim Hakan Sitoci-Ficici
- Universitätsklinikum Carl Gustav Carus, Klinik für Neurochirurgie, Dresden, Deutschland
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Bernhard Rieger
- Short Care Klinik Greifswald, Neurochirurgie, Greifswald, Deutschland
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Thomas Pinzer
- Universitätsklinikum Carl Gustav Carus, Klinik für Neurochirurgie, Dresden, Deutschland
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Mario Wähler
- Lütten Klein Klinik, Neurochirurgie, Rostock, Deutschland
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Hongzhen Jiang
- Chinese PLA General Hospital, Department of Neurosurgery, Beijing, China, Volksrepublik
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Clemens Reinshagen
- Brigham and Women`s Hospital, Dept. of Neurosurgery, Boston, MA, Vereinigte Staaten
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Marek Molcanyi
- Uniklinik Köln, Institut für Neurophysiologie, Köln, Deutschland
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Uta Brautferger
- Arbeitsgruppe Prospective Spine, Köln, Deutschland
| Veröffentlicht: | 18. Juni 2018 |
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Gliederung
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Objective: The strength and stiffness of the hollowed groups were lower than in group A. However, the difference was not statistically significant between groups A and C (p> 0.05), and was obviously different between groups A, B or D (p< 0.01 and < 0.05, respectively). Moreover, the strength and stiffness after filling foams in group C or group D were significantly greater than in group B (p< 0.01 and < 0.05, respectively). Live/dead staining of 3T3 cells confirmed the PU foams biocompatibility. The new PU foams demonstrate adaptability with regards to their stiffening character and excellent cytocompatibility in vitro.
Methods: This study prototyped a first version of an expandable device and conducted a biomechanical study to compare the compressive strength and stiffness of porcine vertebral bodies filled with new adjustable biocompatible PU foams of different prepolymer ratios. The new PU foams demonstrated adaptability with regards to their stiffening behavior and excellent cytocompatibility in vitro.
Results: A pre-set titanium frame was developed for its minimally invasive implantation into the vertebral body (Figure 1 [Fig. 1]). The adaptability of polyurethane foam with regards to its compressive strength and stiffness was tested in a porcine model by comparing biomechanical behavior of vertebral bodies filled with polyurethane foam with normal or hollowed bodies. Lumbar vertebral bodies of pigs are first randomly split into four groups: intact vertebral bodies (A), hollowed vertebral bodies (B) and hollowed bodies filled with foam of two different ratios of the prepolymers (C, D). The compressive strength and stiffness are analyzed to characterize the strength of the interface between the foam and the cancellous bone. For testing cyto-compatibility 3T3 mouse osteoblasts are cultured with preformed PU foam extracts for 4 days.
Conclusion: Polymethylmetacrylate (PMMA) has an about seven to ten times higher elastic modulus than normal cancellous bone resulting in increased stiffness of PMMA augmented vertebral bodies by 174% with significantly increased risk of adjacent fractures in patients suffering from osteoporosis. For a novel spondyloplasty in osteoporosis an expandable vertebral device was prototyped and in situ formable, biocompatible, lysine degradable PU foams (Figure 2 [Fig. 2]) were tested.
