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[Effect of low-intensity pulsed ultrasound on the enchondral bone formation in posterolateral lumbar fusion in rabbits].

OBJECTIVE
To observe the effect of daily low-intensity pulsed ultrasound (LIPUs) therapy on improving the enchondral bone formation in lumbar fusion in rabbit models, and to explore its possible mechanism.


METHODS
Posterolateral noninstrumented bilateral fusions were performed at the L5 approximately L6 levels in 20 New Zealand rabbits. The autograft iliac bone was implanted on the left side, and the hydroxyapatite bioceramic artificial bone on the right. The rabbits were divided into a treatment group and a control group randomly. One week after the surgery, LIUPs was administered for 20 minutes per day for 4 weeks over the fusion site in the treatment group and false treatment was used in the control group. Post-anterior X-ray photographs were taken to determine the conditions of fusion area, and then, rabbits were killed and the fusion tissues were obtained. Chondrocytes were detected by histological and cytological methods.


RESULTS
Compared with the control group, the fusion rate of the treatment group was significantly up-regulated (P<0.05). There was plenty bone trabecula in the fusion area in the treatment group, the number of chondrocytes was also higher than that of the control group (P<0.05), and there was no statistical difference in the number of chondrocytes between the iliac and artificial bone tissues after the treatment(P>0.05).


CONCLUSION
Low-intensity pulsed ultrasound therapy improves the endochondral bone formation in the lumbar spine fusion in rabbit models.