Early knee osteoarthritis (KOA) is difficult to diagnose due to the limited sensitivity of conventional imaging and the heterogeneous presentation. This exploratory study aimed to characterize patients with early KOA symptoms by integrating arthroscopy, MRI, and synovial histopathology, and to assess the complementary value of these modalities. We included 130 adults (> 18 years) with knee pain lasting > 3 months and inconclusive clinical and radiographic findings. Exclusion criteria included advanced radiographic OA (Kellgren–Lawrence grade > 2), previous diagnoses of musculoskeletal, rheumatic disorders or previous knee injury or surgery. MRI was performed before arthroscopy. Isolated minor findings (small focal cartilage defects or mild meniscal changes without structural disruption) were not considered exclusionary. All patients underwent diagnostic arthroscopy, and synovial biopsies were obtained from the medial patella and infrapatellar fat pad. Based on arthroscopic Outerbridge scoring, 24 patients were classified as early KOA (grades 0–2) and 55 as moderate KOA (grades 3–4). Arthroscopy detected early cartilage lesions in 60% of cases, compared with 35% by MRI. MRI WORMS scores for non-cartilaginous structures did not differ between groups. Synovial fibrosis and macrophage infiltration were higher in moderate KOA and correlated with WOMAC pain. Arthroscopy was more sensitive than MRI for early cartilage damage, while MRI provided complementary information on non-cartilaginous structures. Synovial inflammation and fibrosis were already present at early stages. An integrated approach combining arthroscopy, MRI, and synovial histopathology enables refined structural and biological characterization of early KOA and may support patient stratification in disease-modifying trials.
McAlindon et al. (Fri,) studied this question.