A 58-year-old man with a 10-year history of bilateral knee osteoarthritis presents for assessment of disease progression. Clinical examination shows Heberden's nodes on the fingers and Bouchard's nodes on the proximal interphalangeal joints. Which investigation is most appropriate to confirm generalized osteoarthritis and assess polyarticular involvement?

## Investigation of Choice for Generalized Osteoarthritis Assessment **Key Point:** Plain radiographs remain the gold standard and most cost-effective investigation for confirming generalized osteoarthritis and assessing polyarticular involvement across multiple joints. ### Why Plain Radiographs Are the Best Choice Plain radiographs enable: - **Multi-joint assessment:** Simultaneous evaluation of hands, knees, hips, spine, and other joints - **Diagnostic confirmation:** Visualization of hallmark OA features (osteophytes, joint space narrowing, subchondral sclerosis) - **Severity grading:** Kellgren-Lawrence staging applicable across all affected joints - **Cost-effectiveness:** Widely available, low radiation, rapid assessment - **Baseline documentation:** Establishes baseline for monitoring disease progression **High-Yield:** Radiographic features of osteoarthritis include: 1. Joint space narrowing (loss of cartilage) 2. Osteophyte formation (bone spurs) 3. Subchondral sclerosis (bone thickening) 4. Subchondral cyst formation ### Kellgren-Lawrence Grading System | Grade | Radiographic Features | Clinical Correlation | |---|---|---| | 0 | No OA | Normal | | 1 | Doubtful joint space narrowing, osteophytes | Questionable symptoms | | 2 | Definite osteophytes, possible joint space narrowing | Mild symptoms | | 3 | Multiple osteophytes, definite joint space narrowing, sclerosis | Moderate symptoms | | 4 | Large osteophytes, severe joint space narrowing, marked sclerosis | Severe symptoms | **Clinical Pearl:** The presence of Heberden's nodes (DIP joint OA) and Bouchard's nodes (PIP joint OA) in hands, combined with knee OA, indicates generalized osteoarthritis. Plain radiographs of all affected sites confirm polyarticular involvement and establish severity. **Mnemonic — OA Radiographic Features:** **JOSS** — **J**oint space narrowing, **O**steophytes, **S**clerosis, **S**ubchondral cysts.