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]-1ß and IL-6 staining). Lateral menisci and synovia were obtained to evaluate knee joint inflammation (enzyme-linked immunosorbent assay of IL-1ß 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-1ß 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.

Three-Dimensional Imaging and Quantitative Analysis of Blood Vessel Distribution in The Meniscus of Transgenic Mouse after Tissue Clearing.

OBJECTIVE: Blood supply to the meniscus determines its recovery and is a reference for treatment planning. This study aimed to apply tissue clearing and three-dimensional (3D) imaging in exploring the quantitative distribution of blood vessels in the mouse meniscus. MATERIALS AND METHODS: In this experimental study, tissue clearing was performed to treat the bilateral knee joints of transgenic mice with fluorescent vascular endothelial cells. Images were acquired using a light sheet microscope and the vascular endothelial cells in the meniscus was analysed using 3D imaging. Quantitative methods were employed to further analyse the blood vessel distribution in the mouse meniscus. RESULTS: The traditional three-equal-width division of the meniscus is as follows: the outer one-third is the red-red zone (RR), the inner one-third is the white-white zone (WW), and the transition area is the red-white zone (RW). The division revealed significant signal differences between the RW and WW (P<0.05) zones, but no significant differences between the RR and RW zones, which indicated that the division might not accurately reflect the blood supply of the meniscus. According to the modified division (4:2:1) in which significant differences were ensured between the adjacent zones, we observed that the width ratio of each zone was 38 ± 1% (RR), 24 ± 1% (RW), and 38 ± 2% (WW). Furthermore, the blood supply to each region was verified. The anterior region had the most abundant blood supply. The fluorescence count in the anterior region was significantly higher than in the central and posterior regions (P<0.05). The blood supply of the medial meniscus was superior to the lateral meniscus (P<0.05). CONCLUSION: Analysis of the blood supply to the mouse meniscus under tissue clearing and 3D imaging reflect quantitative blood vessel distribution, which would facilitate future evaluations of the human meniscus and provide more anatomical references for clinicians.