[Bone callus: possible assessment with color Doppler ultrasonography. Normal bone healing process].

Conventional US demonstrates bone callus dimensions and structure, which permits to monitor the bone healing process. January, 1993, through May, 1995, we examined 108 patients with simple fractures of humerus, femur and tibia; all the fractures had been treated with an external or intramedullary metallic fixator. All the patients were submitted to conventional and color-Doppler US of the fracture focus on all possible scanning planes. We considered morphological parameters (the presence/absence of vessels, their number and shape) and functional parameters (the resistive index and the presence of a telesystolic notch). Color-Doppler US and the spectral analysis allowed us to add functional data, on bone callus and newly formed bone vascularization, to morphological studies. In the patients with positive fracture evolution, the caliber of afferent vessels progressively increased, their number decreased and branches appeared. The RI progressively increased, up to similar values to those of nutrient vessels (.36 to .90). Within the second month of fracture, a telesystolic notch appears: this indicates a muscular tunic in the vessel wall, meaning a mature, and no longer a newly formed, vessel. The normal evolution of bone healing may be interrupted by several mechanical and biohumoral factors which reportedly act in a similar way by reducing the number of vessels and increasing peripheral resistance in residual vessels because of fibrosclerotic involution of bone healing. Color-Doppler US permits noninvasive, repeatable and nearly real-time monitoring of bone fracture healing, which suggests this technique could be used: -to assess the results of treatment changes (e.g., loading, external fixator adjustments); -to study the definitive callus; -for the medicolegal assessment of delayed bone healing and of pseudoarthrosis; -for real-time treatment planning, according to color-Doppler findings, and to monitor treatment results.