The progression of osteoarthritis is traditionally measured using radiographic joint space width (JSW). Numerous knee radiograph protocols have been developed with various levels of complexity and performance as it relates to detecting JSW loss (ie, joint space narrowing). Sensitivity to joint space narrowing is improved when radioanatomic alignment of the medial tibial plateau is achieved. Semiautomated software has been developed to improve the accuracy of JSW measurement over manual methods. JSW measurements include minimum JSW, mean JSW or joint space area, and JSW at fixed locations.