What radiographic classification system is used to grade knee osteoarthritis?

• A. Kellgren-Lawrence
• B. Outerbridge
• C. Iwano
• D. Samilson-Pfitzer

Answer: (A)

Knee osteoarthritis is graded on X-rays by looking for structural changes such as osteophyte formation and joint space narrowing. The Kellgren-Lawrence scheme is the standard radiographic grading system for knee OA. It grades from 0 to 4, with 0 = no signs, 1 = doubtful osteophyte with possible joint space narrowing, 2 = definite osteophytes with possible narrowing, 3 = multiple osteophytes with definite joint space narrowing, sclerosis, and possible deformity, and 4 = large osteophytes with severe joint space narrowing, marked sclerosis, and deformity. This framework is widely used in both research and clinical practice to quantify OA severity on radiographs.

Other terms refer to different things: Outerbridge assesses cartilage damage seen during arthroscopy rather than radiographs; Iwano is another radiographic grading system but less commonly used for knee OA overall; Samilson-Pfitzer is specific to patellofemoral joint changes, not the general knee.