Radiographic and clinical progressions of the disease are significantly associated but the clinical relevance of the association is questionable.

These results suggest that patients with the less severe radiographic knee OA will experience, over 3 years, the most dramatic disease progression in terms of joint space narrowing. Such patients may be particularly responsive to structure-modifying drugs.

Our method of measurement of JSW may be of potential use in longitudinal studies evaluating the effect of structure-modifying drugs in OA, due to its high level of precision and efficiency. However, although sensitivity to change is markedly better with the digitized method compared with the graduated magnifying lens, we recommend the measurement of mean and minimum JSW in structure-modifying OA trials.