[Modification of bone fracture healing by ultrasound in an animal experiment model].

Both tibiae were osteotomised after medullary nailing in 40 rabbits. In each case the right fracture was treated with ultrasound of 0.1 W/cm2 for 2 minutes 4 times every second day after on week. The left extremity is used as control. An accelerated and increased callus formation and callus maturation were found by ultrasonic therapy. This was possible to be shown on a higher level of the alkaline phosphatase, a higher temperature, and an accelerated calcium and phosphate incorporation in the callus in comparison with the untreated side. The mineralisation by means of ultrasound showed a characteristical three phase behaviour. The mechanism of action is probably the piezo-electric effect of the local tension induction by ultrasound with resultant activation of the metabolism. The advantage of the mineralisation amounted to 2 weeks in contrast to the untreated extremity in the 4th week after the fracture. These findings confirm numerous positive clinical results.