gms | German Medical Science

Objectives: The aim of this current study was to establish a new metaphyseal femoral non-union model in osteoporotic rats by comparing a power-tool versus a manual-tool for fracture creation. This pseudoarthrosis model would allow for further testing of new biomaterials to enhance fracture healing in osteoporotic bone by mimicking the clinical setting.

Methods: Twenty rats were ovariectomized (OVX) and treated with a calcium-, phosphorus-, vitamin D3-, soy- and phytoestrogen-free diet for 6 weeks. Biweekly pQCT measurements over 8 weeks confirmed a significant reduction in the cancellous and total bone mineral density in OVX rats compared to control animals. After 6 weeks, the OVX rats underwent surgery with inducing a distal metaphyseal femoral fracture, either with an experimental Piezoelectric- (n=10) or a control Gigli (n=10) saw. The fracture was internally stabilized with a Y-shaped mini-locking plate. Within each group, five randomly selected rats received Alginate directly into the fracture as a biomaterial. Biweekly X-rays allowed for observing the fracture healing process.

Results and conclusion: After 6 weeks, X-ray evaluation showed a non-union at the fracture site in all rats treated with the Piezoelectric saw. In the Gigli saw group, all animals showed fracture healing in the X-rays and bridging of the initial defect upon histological evaluation.

We conclude that for the creation of a metaphyseal non-union fracture in osteoporotic bone a Piezoelectric saw should be used. This model allows for further testing of biomaterials by closely resembling the clinical setting to enhance healing of fractures with non-union.