Fracture healing: from basic science to role of nutrition.

Fracture healing is a complex event that involves the coordination of different processes: initial inflammatory response, soft and hard callus formation, initial bony union and bone remodeling. This well-orchestrated series of biological events follows a specific temporal and spatial sequence that can be affected by biological factors, such as age and bone quality. There is some evidence that increased age is a considerable factor in the inhibition of fracture repair in human subjects. During aging there is an accumulation of damage that depends on the activation of inflammation processes and on changes in the circulating levels of inflammatory cytokines. In addition to the physiological slow down in the repair process, other conditions such as multiple comorbidities leading to polymedication are a frequent occurrence in elderly patients and can have an influence on this process. A further factor that affects bone metabolism is nutrition: bone quality, fragility fractures risk and fracture healing process are all influenced by the nutritional status. This review provides a summary of the immunological aspects of physiological fracture healing and of those nutritional factors which might play an important role in this process.