Bone regeneration in rat femoral defects after osteotomy with surgical ultrasound

To evaluate bone healing after osteotomy by surgical drill (D) and piezoelectric ultrasound (U), Wistar rats were submitted to femoral osteotomy and submitted to histological analysis. After 60 h, slight (83.3%) and moderate (3.4%) inflammatory areas were frequent in the U defects whereas D group presented moderate (33.3%) and severe (16.6%) inflammatory infiltrate (P<0.001). There was few intramedullary hemorrhaging in U (80%) than D group (100%, P<0.05). On the 7th day, inflammatory areas was less frequent in U (30%) than D osteotomies (93.4%) (P<0.005) and D osteotomies presented larger areas of ossification (median: 47%, quartile: 37-64%) than U group (30%, 18.5-38%; P<0.005). After 30 days, ossification was larger in the U defects (65.9±10.1%) than D group (57±14.5%, P<0.05). There was complete bone remodeling in both groups after 60 days. Piezoelectric ultrasound evokes less postoperative inflammatory response, but delay initial bone ossification.