Multiple joint osteoarthritis (MJOA): What's in a name?

OBJECTIVE: To summarize the current state of the literature regarding multi-joint osteoarthritis (MJOA) and discuss important future directions. DESIGN: A narrative review of the author's work and other key references on this topic with a focus on the Johnston County studies, definitions of MJOA and their impact, multi-site pain in osteoarthritis (OA), genetics and biomarkers in MJOA, and perspectives on future work. RESULTS: MJOA is variably defined and lacks a clear consensus definition, making comprehensive study challenging. Involvement of both symptoms and structural changes of OA in multiple joints in an individual is common, but patterns vary by sex, race/ethnicity, and other factors. Outcomes (e.g., general health, function, falls, mortality) are negatively impacted by a greater whole-body OA burden. Recent genetic and biomarker studies including whole-body OA assessments have begun to shed some light on potentially unique factors in the MJOA population. CONCLUSIONS: Consideration of MJOA is essential for ongoing study of OA phenotypes, epidemiology, risk factors, genetics, biomarkers, and outcomes, to fully understand and eventually limit the negative impact of OA burden on health.