Radial extracorporeal shock wave therapy promotes osteochondral regeneration of knee joints in rabbits

Radial extracorporeal shock wave therapy (rESWT) has been proven to be effective for nonunion fractures. It was, thus, hypothesized that it may be used as a supplement therapy to promote osteochondral regeneration when combined with a scaffold previously prepared by our research group. In the present study, to verify this hypothesis, New Zealand white adult rabbits were anaesthetized and divided into three groups, as follows: Untreated control group, in which full-thickness cylindrical osteochondral defects were created without repairing; scaffold group, in which rabbits were implanted with the scaffolds; scaffold plus rESWT group, in which rabbits were implanted with scaffolds and then treated with rESWT at 2 weeks post-surgery. At 6 and 12 weeks after surgery, the animals were sacrificed. Nitric oxide (NO) levels in the synovial cavity of the knee joints were measured by the Griess method. In addition, macroscopic observation and the gross score according to the International Cartilage Repair Society (ICRS) histological scoring system were determined. Histological evaluation was also performed by hematoxylin-eosin and Safranin O/fast green staining. The results demonstrated that both the scaffold and scaffold plus rESWT treatments significantly reduced NO levels in the synovial cavity at 6 weeks after surgery (P<0.05), whereas no significant difference was observed at 12 weeks after surgery. The ICRS scores of the scaffold and scaffold plus rESWT groups were significantly higher in comparison with those in the control group (P<0.05), and rESWT further increased these scores at 12 weeks after surgery (P<0.05). Histological results revealed that osteochondral regeneration was improved after treatment with scaffold or scaffold plus rESWT, with the latter displaying better results. These data suggested that rESWT improved the osteochondral regeneration when applied in combination with the scaffold, and that one of the underlying mechanisms may involve the reduction of NO in the synovial fluid. Therefore, rESWT may be a useful treatment for knee osteochondral regeneration.