Maturation of the distracted callus. Sonographic observations in rabbits applied to patients

We measured the corticalization of lengthened callus in rabbits and humans with ultrasonography. In rabbits, the echo reflection value was correlated with the strength of the callus; when this value exceeded 70 percent of that of the normal cortex, the callus strength was equal to that of the normal tibia. Clinically, the lengtheners in 8 patients were removed when the echo value exceeded 70 percent, regardless of attained lengthening. Neither fracture nor collapse of the callus ensued. The time required from the end of the lengthening process until the echo reflection value reached 70 percent was correlated with the patients' age.