MRI-based semiquantitative scoring of joint pathology in osteoarthritis.

The use of MRI techniques to investigate tissue pathology has become increasingly widespread in osteoarthritis (OA) research. Semiquantitative assessment of the joints by expert interpreters of MRI data is a powerful tool that can increase our understanding of the natural history of this complex disease. Several reliable and validated semiquantitative scoring systems now exist and have been applied to large-scale, multicentre, cross-sectional and longitudinal observational epidemiological studies. Such approaches have advanced our understanding of the associations of different tissue pathologies with pain and improved the definition of joint alterations that lead to disease progression. Semiquantitative MRI outcome measures have also been applied in several clinical trials in OA. Indeed, interest in MRI-based semiquantitative scoring systems has led to the development of several novel scoring systems that can be applied to different joints: a knee synovitis scoring system based on contrast-enhanced MRI; the MRI Osteoarthritis Knee Score (MOAKS); the Hip Osteoarthritis MRI Score (HOAMS); and the Oslo Hand Osteoarthritis MRI score (OHOA-MRI). Although these new scoring systems offer theoretical advantages over pre-existing systems, whether they offer actual superiority with regard to reliability, responsiveness and validity remains to be seen.