Publikationsserver der RWTH Aachen University
Adhäsivsystem aus amphiphilem Knochenhaftvermittler und dualhärtendem Zement als Alternative zur geschraubten Fixation von Osteosyntheseplatten im Mittelgesichtsbereich
Abstract
dc:descriptionIn this study, an alternative fixation technique to affix thin cortical bone fragments to osteosynthesis plates in the surgical therapy of midfacial fractures is presented. The current surgical therapy involves internal fixation in which bone fragments are fixed in their anatomical positions with osteosynthesis plates and corresponding screws until bone healing is complete. This often causes new fractures to fragile bones while drilling pilot holes or trying to insert screws. The punctually adhesive fixation of osteosynthesis plates using a common cement based on polymethylmethacrylate (PMMA) and methacrylate (MMA) applying through the screw holes of the plate could offer a viable alternative for fixing the plates without screws. However, adhesion forces cannot be built up because of the different wetting properties of the hydrophilic bone and the hydrophobic MMA monomers of the cement. Therefore, a new amphiphilic bone bonding agent was developed, similar in composition to the dentin bonding agents being in clinical use for years, which is able to bond with both hydrophilic bone and hydrophobic MMA monomers of cement. In order to allow the initiation of polymerisation determined individually through the use of light, as it is desired in the fixation of osteosynthesis plates, the common PMMA cement was modified with a photoinitiator. Osteosynthesis plates with screw holes of 1.3 mm diameter were punctually fixed to cortical bone samples of bovine femur and also to the cortical cranium of rabbits using the bone bonding agent and the modified lightcuring PMMA cement. After storing the samples up to 8 weeks in a 0.9% saline solution at 37°C in vitro tension tests were implemented in order to determine the adhesive bonding strengths. For the cortical bone samples of bovine femur bonding strengths of 7.2 MPa up to 29.9 MPa were measured. For the cranium of rabbits the bonding strengths were 18.8 MPa up to 28.9 MPa. Reference samples, prepared without bone bonding agent, showed 0.2 MPa or less. Other reference samples were prepared fixing the plates on the cranium of rabbits with screws. The detected average pull out strength was 20.9 MPa. The results of the present in vitro investigations show that the deleloped amphiphilic bone bonding agent establishes an interlayer between the hydrophilic bone surface and the hydrophobic PMMA cement which results in adhesive bonding between them. The bonding is also stable against hydrolysis. Reference samples confirmed that adhesive bonding between hydrophilic and hydrophobic bonding partners is impossible without the amphiphilic bonding agent. This new method of the adhesive fixing of osteosynthesis plates could have important clinical meaning in cases where conventional fixation of screws and plates find their limitations, as seen in comminuted fractures. With the detected adhesion forces of 7 to 28 MPa, it is to be assumed that the adhesive fixation system is able to secure bone fragments from the non-load bearing midfacial regions in their orthotopic positions until fracture consolidation is complete.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2009
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Endres, Kira
- Contributors dc:contributor
-
- Marx, Rudolf
Subjects
dc:subject × 14Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger