Nandrolone decanoate in induced fracture nonunion with vascular deficit in rat model: morphological aspects.

BACKGROUND: The nonunion fracture is a relatively frequent complication in both human and veterinary medicine. Specifically, atrophic fracture nonunions are difficult to treat, with revision surgery usually providing the best prognosis. Anabolic steroids, such as nandrolone decanoate (ND), have been reported to have beneficial clinical effects on bone mass gain during osteoporosis; however, their utility in promoting regeneration in atrophic nonunions has not been documented. Our objective was to examine morphological changes induced by the ND in experimental fracture nonunion with vascular deficit in the rat model. METHODS: Fourteen adult Wistar rats had an atrophic fracture nonunion induced in the diaphysis of their left femur. Rats were allocated into two groups: control group and nandrolone decanoate group. Rats in the latter group were given nandrolone decanoate (1.5 mg/kg IM, once a week, during 4 weeks after confirmation of fracture nonunion radiographically). Radiographic and anatomopathological examination, micro-tomography and histological analysis were assessed to characterize the morphological changes promoted by the nandrolone decanoate use. RESULTS: Based on radiology, anatomopathological evaluation, computed micro-tomography and conventional microscopy, nandrolone decanoate promoted bone regeneration at the fracture nonunion site by increasing the cellularity at the fracture site. Percentage of collagen was not significantly different between groups, consistent with high-quality regenerated bone. CONCLUSION: The anabolic steroid nandrolone decanoate improved bone mass and regeneration without affecting collagen production and therefore has potential for improving outcomes for atrophic fracture nonunion.

Novel rat model of nonunion fracture with vascular deficit.

Nonunion fractures occur frequently in humans, with profound implications (medical and non-medical). Although there are numerous animal models to study pathogenesis and treatment of nonunion fractures, there is apparently the lack of a definitive model for atrophic nonunion fracture. Therefore, the objective was to develop a low-cost rat model of nonunion fracture with a vascular deficit that enabled standardized quantitative analysis of bone growth and regeneration. The model was developed with two surgeries, performed apart. The first involved osteotomy of the femur diaphysis, removal of periosteum and endosteum, isolation of the fracture site using a latex artefact (Penrose drain tube), and reduction of the fracture using an intramedullary pin, whereas the second surgery was to remove the latex artefact. Based on radiographic imaging, micro-CT and histological analyses done 125 days after the fracture was induced, there was clear evidence of atrophic nonunion fracture, without pin migration or specimen loss. Perceived advantages of this model included low cost, ease of reproducibility, lack of specimen loss, and, finally, the potential to assess bone growth and regeneration under poor vascular conditions.