Roles of gas molecules and related factors in knee cartilage injury and repair: a bibliometric visualization analysis of research hotspots.

After knee cartilage injury, the self-repair capability is limited, making it prone to progression into osteoarthritis. Recently, gas signaling molecules such as nitric oxide and oxygen, along with reactive oxygen species and other factors associated with oxygen metabolism, have increasingly demonstrated critical roles in the field of knee cartilage injury and repair. However, there are few reports on the evolving research hotspots in this field. Based on the Web of Science Core Collection database, this study conducted a bibliometric and visualization analysis of 245 publications related to the roles of gas molecules and other factors associated with knee cartilage injury and repair. The results reveal a clear evolutionary trend in the research hotspots of this field, characterized by a transition from basic mechanism exploration to translational application transformation. (1) Basic mechanism exploration stage: The keyword co-occurrence network identified a tightly-knit cluster comprising core nodes such as "nitric oxide," "chondrocytes," "apoptosis," "reactive oxygen species," "oxidative stress," and "hypoxia." Co-citation analysis revealed that classic studies had demonstrated that nitric oxide mediates chondrocyte injury and matrix degradation through the inducible nitric oxide synthase-nitric oxide-apoptosis signaling pathway. Subsequent research further clarified the dual regulatory roles of oxygen and reactive oxygen species, confirming the significance of the hypoxia-inducible factor pathway in cartilage metabolism. Burst detection revealed that core literature from this period, such as studies on inducible nitric oxide synthase inhibition and hypoxic culture, maintained a high citation rate for 5-8 years, thereby forming a long-term, stable knowledge foundation in the field. (2) Translational application transformation stage: Emerging translational and biomaterial-related nodes, including "graphene oxide," "cartilage tissue engineering," and "nanomedicine," together with gas-based interventions such as "ozone therapy," have surged and formed strong interdisciplinary connections with "osteoarthritis" and "cartilage repair." This shift illustrates a change in perspective from "injury mechanisms" to "repair interventions." Co-citation analysis confirmed that the most significant recent literature focuses on the relationship between reactive oxygen species, cartilage aging, and osteoarthritis, as well as on nanoscale drug delivery systems for directly clearing nitric oxide and reactive oxygen species. Burst detection revealed that "synergistic intervention of materials and gases" has emerged as the most active frontier hotspot. These findings suggest that gas signaling molecules and oxygen metabolism-related factors are core mediators regulating knee cartilage injury and repair. Research hotspots have shifted from exploring the inducible nitric oxide synthase-nitric oxide-apoptosis signaling pathway and oxidative stress in cartilage injury to translational applications in nanomedicine and biomaterials for cartilage repair. Future research may benefit from elucidating the mechanisms underlying multi-factor interactive networks and promoting the clinical translation of gas-targeted regulatory strategies.