Functional Brain Imaging in Knee Osteoarthritis: A Bibliometric Analysis of Research Trends and Emerging Clinical Perspectives.

Knee osteoarthritis (KOA) is a leading cause of chronic disability, and the well-documented discordance between structural joint damage and pain experience suggests that central nervous system mechanisms contribute to symptoms independently of peripheral pathology. Functional magnetic resonance imaging (fMRI) has increasingly been used to investigate brain network alterations in KOA, yet the research landscape of this emerging field remains unmapped. We characterized publication trends, collaboration patterns, and methodological characteristics of brain fMRI research in KOA. Following PRISMA 2020 principles adapted for evidence mapping, we searched the Web of Science Core Collection on September 6, 2026, and included 43 English-language original studies (2008-2027) after 2-stage independent screening with chance-adjusted inter-reviewer agreement. Publication output, collaboration networks, keyword co-occurrence and burst detection, and paradigm-metric-target coupling were analyzed using VOSviewer, CiteSpace, and the bibliometrix package in R. Annual output fluctuated between one and six publications, peaking at six in 2022. The United States (n = 20) and China (n = 17) were the most productive countries and formed the leading bilateral collaboration dyad. Resting-state fMRI was the most frequently used paradigm (24 studies, 55.8%) and functional connectivity the most frequently applied analytical metric (25 studies, 58.1%); the medial prefrontal cortex (13 studies, 30.2%) and the sensorimotor cortex (12 studies, 27.9%) were the most frequently investigated brain targets. Author-keyword and Keywords Plus analyses yielded complementary thematic structures comprising ten modularity-based clusters (modularity Q = 0.6268, weighted mean silhouette = 0.8522); the most recent keyword bursts (2024 onward) were "pain," "functional connectivity," and the Keywords Plus-derived term "hip." These findings describe publication activity and methodological preferences within the WoSCC-indexed, English-language literature and do not establish the clinical validity of any imaging measure.