[Optimizing the degree of fixation stability based on the strain theory]

Elastic flexible internal fixation stabilizes the fracture using the principle of splinting. Foregoing absolute stability using compression serves to maintain the mechano-biological induction of fracture healing. It also serves to maintain the blood supply to soft tissues and bone. The healing pattern seen after flexible fixation corresponds to that of secondary bone healing. It starts early and requires less precision, which in turn helps to avoid iatrogenic damage during reduction and stabilization.Prognosis based alone on the degree of fracture mobility is inadequate because spontaneous healing can be observed in wild animals even with great mobility while in turn minimal instability of closely reduced fractures may result in delayed or non-union. The determining factor for tissue differentiation is not mobility but deformation (strain) of the repair tissue. While tissue strain depends on mobility, it depends even more so - and is all too often disregarded - on the distance between the moving fracture surfaces. Strain plays an important role when choosing the method of immobilisation and predicting an outcome, determining the induction and tolerance of the repair tissue.