Imaging biomarkers of spine osteoarthritis

While there is an acknowledged need for biomarkers to progress arthritis research, imaging biomarkers for the spine have lagged behind those for peripheral joint osteoarthritis. Progress has been slow for a number of reasons. First and perhaps most importantly, there is currently no international agreement on definition of spine osteoarthritis (OA), either histologically or on imaging. Secondly, spine OA comprises two main pathologies, and debate continues as to whether they are separate entities or linked: degenerative disc disease and facet joint arthritis. Imaging those neighbouring joints is not straightforward and usually requires separate imaging investigations. Thirdly, it is only just becoming clear to what extent changes on imaging are associated with the main clinical problem - back pain. To compound the problem, the organisation of clinical services usually means that different specialties tend to focus on different anatomical areas, so a combined approach is not commonly adopted. Systematic evaluation of facet joints in epidemiological study is still in its infancy. Regardless of these hurdles, we have attempted in this review to summarise the state of play of imaging biomarkers in the spine with the emphasis on degenerative disc disease. MR imaging clearly leads the way and there exists a variety of specialist techniques such as T1rho and which may offer spine research imaging biomarkers in the future.