Experimental Study Of Low-energy Shock Waves In Microfracture Holes In The Repair Of Articular Cartilage Defects In A Rabbit Model

Objectives In this study, low-energy shock waves were applied in microfracture holes to repair full-thickness cartilage defects in rabbits, and the repair results were observed and analyzed. The aim was to investigate a novel method of enhancing microfracture by determining whether low-energy shock waves in microfracture holes would facilitate cartilage repair in a rabbit model.Methods Full-thickness cartilage defects were created at the medial femoral condyle of 36 mature New Zealand White rabbits without penetrating subchondral bone. The rabbits were randomly divided into three groups. In shock waves with microfracture group, low-energy shock-wave therapy was performed in microfracture holes (diameter,1 mm) at an energy flux density of 0.095 mJ/mm2 and 200 impulses by endoscopic probe (diameter,0.8 mm) of pneumatic shock wave generator. In microfracture group, microfracture was performed alone. The untreated rabbits served as a control group. At 4,8, and 12 weeks after the operations, repair tissues at the defects were analyzed stereologically, histologically, and immunohistochemically. The degree and the quality of repair results were evaluated according to Wakitani histologic scoring systems.Results The defects were filled gradually with repair tissues in shock waves with microfracture group and microfracture group, and no repair tissues had formed in the control group at 12 weeks post operation. There was no obviously difference in repair tissues between two experimental groups at 4 weeks after operation. Repair tissues in shock waves with microfracture group contained more chondrocytes, proteoglycans, and collagen typeâ…¡than those in microfracture group at 8 and 12 weeks post operation. In microfracture group, fibrous tissues had formed and increased at the defects at 8 and 12 weeks. Histologic analysis of shock waves with microfracture group showed a better Wakitani score (P<0.05) than in microfracture group at 8 and 12 weeks after operation.Conclusions In the repair of full-thickness articular cartilage defects in rabbits, low-energy shock waves in microfracture holes facilitated the production of hyaline-like cartilage repair tissues more than microfracture alone. This model demonstrates a new method of improving microfracture.