Aim of this study was to evaluate effects of Low-intensity pulsed ultrasound on repair of articular cartilage defects. Low-intensity pulsed ultrasound (Lipus) can induce the differentiation and activation of chondrocytes. This study was designed to evaluate the effect of Lipus on articular cartilage defects in a sheep. Eight sheep were divided in to two groups. The animals received bilateraly, articular cartilage defects 4 mm in diameter and 2 mm in deep on the patellar groove and experimental groups were treated with intensity 200 mW/cm², 20 min/day with low-intensity pulsed ultrasound for 2 month. Then both knee joints underwent surgery for remove of formed tissue sample from defects.The samples were evaluated by Quantitative real-time polymerase chain reaction (qRT-PCR), Safranin-o staining, Immunofluorescence Staining and Morphological characterization. The best and worst sample per group according to Macroscopic and micriscopic scoring were icentified. The results showed that the operated groups with-Lipus-treatment and without-Lipus treatment had considered statistically significant. Gross photography revealed that the defects in experimental groups were filled with proliferative tissue, while in control groups, a thin layer of proliferative tissue was formed in defects. qRT-PCR results showed the expression of coll2, sox9, aggrecan and Osteocalcin in experimental groups. Intense safranin-O staining show the formation cartilage tissue in ultrasound treated group, while loose safranin-o-staining were observed at the control groups. Immunofluorescence staining showed the type 2 Collagen protein expression. We suggest that low-intensity pulsed ultrasound provide the mechanistic basis force for articular cartilage repair and effective treatment modality for improving of articular cartilage defects.

本研究的目的是评估低强度脉冲超声对关节软骨缺损修复的影响。低强度脉冲超声（Lipus）可以诱导软骨细胞的分化和活化。本研究旨在评估 Lipus 对绵羊关节软骨缺损的影响。八只羊被分成两组。动物接受双侧关节软骨缺损，髌骨沟直径为 4 mm，深度为 2 mm，实验组接受 200 mW/cm ^{2强度治疗}, 20 分钟/天，使用低强度脉冲超声 2 个月。然后对两个膝关节进行手术以从缺损处去除形成的组织样本。通过定量实时聚合酶链反应（qRT-PCR）、番红-o染色、免疫荧光染色和形态学表征对样品进行评估。根据宏观和微观评分，每组最好和最差的样本被选中。结果表明，接受Lipus治疗和不接受Lipus治疗的手术组被认为具有统计学意义。大体摄影显示，实验组的缺损处充满了增生组织，而对照组的缺损处形成了一层薄薄的增生组织。qRT-PCR结果显示实验组中coll2、sox9、聚集蛋白聚糖和骨钙素的表达。强番红-O染色显示超声处理组软骨组织形成，而在对照组观察到松散番红-O染色。免疫荧光染色显示2型胶原蛋白表达。我们认为，低强度脉冲超声为关节软骨修复提供了机械基础力，为改善关节软骨缺损提供了有效的治疗方式。