Evaluation of a water-resistant and biocompatible adhesive with potential use in bone fractures

The use of osteosynthesis materials when complex fractures are presented is well known. However, the use of these materials has not achieved a correct fixation and reduction of all bone fragments. Therefore, an adhesive for bones would provide a simple and quick method to fix this kind of fractures. The aim of this work is to propose and to evaluate an adhesive based on chitosan hydrogels that could have a potential use as a bone adhesive underwater and will not develop cytotoxic effects. Ionically and covalently crosslinked hydrogels based on chitosan were used in this study. Butt joint test with bovine cancellous bone specimens were used in order to measure the tensile bond strength (TBS) in ideal (completely dry) and physiological (immersed in water at 37 degrees C) conditions. Additionally, TBS was estimated as a function of time of bone specimens immersed in water at 37 degrees C. Cell viability was studied using MTT assay and cell morphology on the adhesive surface was examined by scanning electron microscope. Mechanical studies revealed that only covalently crosslinked hydrogels maintain their TBS at physiological condition with respect to the dry environment. In addition, it was observed that the TBS, using only covalently crosslinked hydrogels adhesives, dramatically changes as a function of time and its behavior increases as calcium carbonate and hydroxyapatite is added. Finally, in vitro cell testing of covalently crosslinked hydrogel with calcium carbonate and hydroxyapatite exhibited excellent biocompatibility. Therefore, this formulation is proposed as a potential candidate for clinical use in orthopedic surgery.