Single-Dose Radial Extracorporeal Shock Wave Therapy Modulates Inflammation During Meniscal Tear Healing in the Avascular Zone.

Background: Extracorporeal shock wave therapy (ESWT) promotes tissue healing by modulating inflammation, which has implications for meniscal tear healing in the avascular zone.
Purpose: To evaluate the effects of a single dose of radial ESWT on the healing process and inflammation of the meniscus and knee joints after meniscal tears in the avascular zone.
Study Design: Controlled laboratory study.
Methods: Avascular tears were induced in the medial meniscus (MM) of 72 Sprague-Dawley rats. One week postoperatively, the rats received a single session of radial ESWT with a Power+ handpiece (ESWT group; n = 36) or with a fake handpiece (sham-ESWT group; n = 36). The rats were then euthanized at 2, 4, or 8 weeks postoperatively. The MMs were harvested for analysis of healing (hematoxylin-eosin, safranin O-Fast Green, and collagen type 2 staining) and inflammation (interleukin [IL]-1β and IL-6 staining). Lateral menisci and synovia were obtained to evaluate knee joint inflammation (enzyme-linked immunosorbent assay of IL-1β and IL-6). Cartilage degeneration was assessed in the femurs and tibial plateaus using safranin O-Fast Green staining.
Results: The ESWT group showed significantly better meniscal healing scores than the sham-ESWT group at 4 ( P = .0066) and 8 ( P = .0050) weeks postoperatively. The IL-1β level was significantly higher in the sham-ESWT group than in the ESWT group at 2 (MM: P = .0009; knee joint: P = .0160) and 8 (MM: P = .0399; knee joint: P = .0001) weeks. The IL-6 level was significantly lower in the sham-ESWT group than in the ESWT group at 2 (knee joint: P = .0184) and 4 (knee joint: P = .0247) weeks but higher at 8 weeks (MM: P = .0169; knee joint: P = .0038). The sham group had significantly higher osteoarthritis scores than the ESWT group at 4 (tibial plateau: P = .0157) and 8 (femur: P = .0048; tibial plateau: P = .0359) weeks.
Conclusion: A single dose of radial ESWT promoted meniscal tear healing in the avascular zone, modulated inflammatory factors in the menisci and knee joints in rats, and alleviated cartilage degeneration.
Clinical Relevance: Radial ESWT can be considered a potential option for improving meniscal tear healing in the avascular zone because of its ability to modulate inflammation.
Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: This work was supported by National Key R&D Program of China (2021YFA1201303), Clinical Research Plan of SHDC (SHDC2022CRT021), National Natural Science Foundation of China (81972129 and 82072521), The Introduction Project of Clinical Medicine Expert Team for Suzhou (SZYJTD201714), Shanghai Talent Development Funding Scheme (2020080), Science and Technology Innovation Project of General Administration of Sport of China (22KJCX010), and Medical Engineering Joint Fund of Fudan University (YG2022-14). AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.