Abstract
BackgroundReconstruction of metaphyseal fractures represents a clinical challenge for orthopedic surgeons. Especially in osteoporotic bone, these fractures are frequently accompanied by osseous substance defects. In order to ensure rapid mobilization of patients, high stability requirements must be met by osteosynthesis. Various bone graft materials have been introduced in the past, such as autologous bone or exogenous bone substitute materials. These are used as bone void fillers or as augmentation techniques to ensure safe fixation of osteosynthesis. New calcium phosphate-based bone void-filling materials could be a promising alternative to autologous bone or to the currently and widely used polymethylmethacrylate (PMMA)-based cement. The aim of this study was to evaluate a novel paste-like bone void filler in vivo and in vitro with regard to biocompatibility and osteoconductivity.MethodsIn addition to in vitro testing of cell compatibility using pre-osteoblasts (MC3T3-E1), 35 Wistar rats were treated in vivo with implantation of various material mixtures based on calcium phosphate and aluminum oxide reinforcement in a metaphyseal drill hole defect. After 4 weeks, an examination by micro-computed tomography (μCT) and histology was performed.ResultsThe in vitro analysis showed good biocompatibility with a high cell survival of osteoblasts. In the in vivo experiments, a significantly higher bone ingrowth compared to the empty defect was shown by μCT and histological analysis. Here, the group receiving material reinforced with aluminum oxide (Al2O3) showed a bone volume/tissue volume (BV/TV) of 89.19% compared to a BV/TV of 83.14% for the empty defect (p = 0.0013). In the group treated with a polysaccharide matrix, no increase in BV/TV was observed given a mean ratio of 80.14%. Scoring of histological sections did not reveal a significant difference between CaP and CaP that was substituted with Al2O3.ConclusionThe results of this study show an encouraging first step towards the development of new pasty, bone void-filling materials. We demonstrated that a new paste-like bone-filling material, based on calcium phosphate granulates and aluminum oxide to provide strength, exhibits good biocompatibility and osteoconductivity. Further biomechanical test in an osteoporotic animal model will have to be performed, to prove feasibility in metaphyseal defects.
Highlights
Fracture fixation of the weight-bearing skeleton can be challenging
Substrates on beta tricalcium phosphate basis are in the meantime often used bone graft substitutes
We added aluminum oxide, which is supposed to get hooked in the defect and for example, Fig. 2 a–c MC3T3-E1 cells exhibit good survival rate on PMMA control, calcium phosphate (CaP), and Al2O3
Summary
Fracture fixation of the weight-bearing skeleton can be challenging. Early loading and precise fracture reduction have a major impact on the long- and short-term outcome, especially in older patients. Metaphyseal fractures with bone defects in osteoporotic bone remain a continuous surgical problem. Due to the characteristics of osteoporotic bones, including reduced trabecular thickness and limited implant fixation, the clinical management of osteoporotic fractures is an important issue in orthogeriatric traumatology. Given the reduced bone quality and prolonged fracture healing, augmentation techniques may be necessary to ensure fracture reduction and fast mobilization. In osteoporotic bone, these fractures are frequently accompanied by osseous substance defects. Various bone graft materials have been introduced in the past, such as autologous bone or exogenous bone substitute materials. These are used as bone void fillers or as augmentation techniques to ensure safe fixation of osteosynthesis. The aim of this study was to evaluate a novel paste-like bone void filler in vivo and in vitro with regard to biocompatibility and osteoconductivity
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