[Efficiency of low-intensity pulsed ultrasound on distraction osteogenesis in case of delayed callotasis -- clinical results].

Aim: Low-intensity pulsed ultrasound has been proven to accelerate fracture healing both clinically and experimentally. In this study the influence of low-intensity pulsed ultrasound during distraction-osteogenesis in case of delayed callotasis was investigated.

Method: 20 patients could be included in this study. 16 patients initially were treated because of fractures of the lower leg, 2 because of fractures of the femur with resulting shortening of the afflicted limb. One patient suffered from chronic osteitis at the thigh and one from chronic osteitis at the upper arm without previous trauma. Because of delayed callotasis an adjunctive ultrasound treatment device was transcutaneously applied (frequency 1.5 MHz, signal burst width 200 microseconds, signal repetition frequency 1.0 kHz, intensity 30 mW/cm (2)) with the transducer placed at the distraction zone for 20 minutes daily. In all cases in-home treatment was performed. Evaluation was done by radiographic and sonographic controls of the distraction zone during examination of all patients at the outpatients' department every 3-4 weeks.

Results: Progress of callotasis was achieved in 15 out of 20 patients. Patients who were smokers during ultrasound therapy showed lower healing rates than those who never smoked. 2 patients suffering from osteitis of the tibia and missing callotasis had to be amputated. 3 other patients needed additional operative treatment including cancellous bone grafts because of missing new bone formation. Negative effects of low-intensity pulsed ultrasound during therapy could not be detected.

Conclusion: We conclude that ultrasound treatment can accelerate bone maturation and formation in distraction osteogenesis, sometimes even in states of poor callotasis. It may provide a method of great promise in cases where delayed bone formation during distraction osteogenesis occurs.