ULTRASOUND ASSESSMENT OF NEW BONE-FORMATI ON DURING DISTRACTION OSTEOGENESIS - TECHNIQUE, OPTIONS, AND RESULTS

In a prospective study 20 patients were monitored with serial sonogram s and radiographs during distraction osteogenesis at the lower limb. A ll sonograms were obtained in four planes using a 7.5 MHz transducer. The distraction gap was seen as a sonolucent area in all patients afte r corticotomy. At an average of 20.7 (14-28) days after the beginning of the distraction, echogenic foci occurred and showed increasing long itudinal alignment with further distraction. Radiographical signs of b eginning mineralization were seen an average of 48.3 days after the st art of the distraction. Exact measurement of the distraction gap was p ossible in all patients during lengthening. Bone healing complications and hematoma could be detected by ultrasound. A rapid increase of bon e mineralization was seen after the distraction was stopped. With incr easing cortication of the regenerate bone, sonograms showed a hyper-re flecting solid line so that further mineralization and the time of rem oval of the fixator could not be assessed by ultrasound. Ultrasound is more sensitive than radiography in identifying new bone formation dur ing distraction, measuring the length of the distraction gap, and dete cting early bone-healing complications and can therefore reduce the ne ed for radiographs.